MANUAL OF PROCEDURES FOR RIGID PAVEMENT … · method eliminates the need for placing two courses...
Transcript of MANUAL OF PROCEDURES FOR RIGID PAVEMENT … · method eliminates the need for placing two courses...
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
TABLE OF CONTENTS
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Page
1.0 Introduction ............................................................................................................................................... 1
2.0 General ...................................................................................................................................................... 2
3.0 Inspection .................................................................................................................................................. 3
4.0 Mechanical Equipment .............................................................................................................................. 5
5.0 Batch Plants ............................................................................................................................................... 9
6.0 Subgrade .................................................................................................................................................. 10
7.0 Subbase .................................................................................................................................................... 11
8.0 Forms ....................................................................................................................................................... 13
9.0 Joints ........................................................................................................................................................ 15
10.0 Sawing and Forming Joints ..................................................................................................................... 20
11.0 Reinforcement ......................................................................................................................................... 24
12.0 Moisture and Mix Control ....................................................................................................................... 26
13.0 Placing and Speading .............................................................................................................................. 27
14.0 Operation of Transverse Finishing Machine ........................................................................................... 29
15.0 Operation of Combination Float Finisher ............................................................................................... 32
16.0 Slip Form Paving ..................................................................................................................................... 34
17.0 Field Checking ........................................................................................................................................ 37
18.0 Final Finishing ......................................................................................................................................... 40
19.0 Curing ...................................................................................................................................................... 43
20.0 Work to be Done Later ............................................................................................................................ 46
21.0 Hot Weather Construction ....................................................................................................................... 49
22.0 Cold Weather Construction ..................................................................................................................... 51
23.0 Job Control Testing and Sampling .......................................................................................................... 52
24.0 Pavement Cores ....................................................................................................................................... 54
25.0 Surface Smoothness ............................................................................................................................... 55
26.0 Measurement ........................................................................................................................................... 56
27.0 Concrete Pavement Repairs .................................................................................................................... 57
Check List for Inspection of Concrete Pavements .................................................................................. 62
Documentation Procedures ..................................................................................................................... 66
Glossary ................................................................................................................................................... 72
Index ........................................................................................................................................................ 77
Note: Any addendum to this manual to be inserted immediately following glossary.
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STATE OF OHIO DEPARTMENT OF TRANSPORTATION
1.0 Introduction
Intent of Manual
This manual is intended to serve as a guide to the
Engineer and Inspector during the construction of
Portland cement concrete pavements. In order to
construct pavements meeting specification
requirements, personnel need to have a thorough
knowledge of the plans, specifications, proposal
notes, and standard drawings. This manual does not
in any manner alter or replace these governing
regulations, but is a supplement to them. The normal
sequence of inspection procedure is outlined to assist
project personnel in performing their duties.
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STATE OF OHIO DEPARTMENT OF TRANSPORTATION
A Portland cement concrete pavement must be
constructed so that it will:
1. Provide a smooth riding surface satisfactory to
the traveling public.
2. Be durable when subjected to natural weathering
and chemicals used for snow and ice control.
3. Be capable of substaining the traffic which it is
intended to carry.
4. Be of sufficient skid resistance to eliminate
slippery conditions when wet.
While it may be that the quality of the riding
surface is the chief element of construction by which
the public either approves or condemns a pavement,
this element is of no greater importance than
durability and structural strength. All desirable
elements of a good pavement are a product of the
workmanship of the contractor and the engineering
and inspection personnel assigned to the work.
2.1 Construction, Culminationof Effort
The actual construction is the culmination of all
previous effort involving many ideas covering
research, traffic study, safety, construction materials
(including soils), design and finance. The entire
procedure is judged, however, by how well the
construction work is done and this responsibility falls
directly upon the contractor and his forces and upon
the Engineer and his Inspectors.
2.2 Every Step Important
Every step of construction, from the preparation of
the subgrade and subbase through curing and opening
to traffic, has a definite effect on the rideability,
durability and structural integrity of the finished
pavement. The text herein is designed to point out
and emphasize the purpose and importance of the
various stages of a concrete paving operation. The
composition of the mix and the elements of concrete
control are not discussed in detail because this phase
of the work is covered in the Manual of Procedures
for Concrete.
2.0 General
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3.0 Inspection
3.1 Assignment of Personnel
Prior to starting concreting operations, inspectors are
assigned to the project and instructed in their various
duties by the Engineer. Also, all necessary equipment
used on the project must be checked for conformance
to the requirements as set forth in the specifications
and approved by the Engineer before concreting may
begin.
3.2 Knowledge of Specifications
It should be emphasized that when a contract is
entered into it is thereby agreed that work shall be in
accordance with contract requirements. To enforce or
not enforce requirements is not a matter of opinion
but is expected by all concerned. Contract
requirements and plan details can be changed only as
a result of negotiation between the Contractor and the
Department and must be covered by a change order.
Obviously, all concerned with inspection and
supervision of construction should be familiar with
specification requirements and plan details and adhere
to them at all times. Most unsatisfactory work can be
traced to lack of enforcement of the specification
requirements.
Engineering supervision should be arranged so
that inspectors check all details of fine grade and
pavement placed during each day. This includes
detailed examination of every joint from placing the
dowel bar assembly to sawing and sealing. A good
practice is to travel up one side of the work and down
the other, repeating the cycle throughout the day.
3.3 Pavement Inspection
Pavement inspection is not merely observation. It is
constant checking to see that all work is being
performed in accordance with good construction
practice and the controlling specifications. At times it
involves stopping operations, reworking or replacing
materials or requiring that work be done over when it
is not correct, and changing methods or materials
when results are unsatisfactory.
When changes in procedure are indicated
because of unsatisfactory pavement results, operations
must be suspended until the changes are made.
Nothing is gained by permitting paving operations to
continue when the resulting pavement is not
satisfactory. It is the responsibility of the Inspector to
bring such matters to the attention of the Engineer at
once for a decision.
The quality of a concrete pavement is a direct
reflection of the quality of workmanship. A pavement
that is durable and that has a good riding surface is
produced only by the constant practice of good
construction methods. Any deviation from good
practice at any time or place will have an adverse
effect on final pavement quality.
Good riding qualities depend on uniformity of
construction. Uniformity begins at the batch plant. If
the batch plant produces nonuniform batches, no
amount of “first-aid” or “emergency” actions at the
paving operation will produce satisfactory, uniform
pavement.
The Concrete Control Inspector’s job is to
check the handling, proportioning and mixing of
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materials according to specifications and to
assure, as nearly as possible, a constant condition of
workability and quality in the resulting concrete. The
two principal sources of difficulty in maintaining
uniform concrete are segregated aggregate and
varying moisture content of the aggregate.
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4.0 Mechanical Equipment
4.1 General
The riding qualities of a pavement are dependent to a
great extent on the proper operation of mechanical
finishing equipment. The equipment must be in
correct adjustment. It is almost impossible to correct,
by hand finishing a poor surface left by the
equipment. Frequent checking and minor adjustments
as required to compensate for changing conditions
will do much to eliminate surface irregularities.
4.2 Adjustments, Contractor’s Function
Adjustments of equipment are a function of the
Contractor’s forces. Department personnel are not
expected to adjust or advise the Contractor how to
adjust and maintain mechanical equipment, but they
are expected to observe checking of all equipment.
The Inspector should be able to recognize when such
equipment is out of adjustment or not coordinated
with the balance of the paving train. The following
information on spreaders and finishing equipment is
given to provide some knowledge on the operation of
such equipment.
4.3 Spreaders
Concrete spreaders are required when the width of
pavement being placed in one operation is 3.6 meters
(12 feet) or more and the area of any given width
exceeds 8,300 square meters (10,000 square yards).
They must be adjusted to leave the proper amount of
concrete to build the slab. The amount left is
determined by the elevation of a strike off plate which
is located behind the screw, paddle or hopper which
distributes the concrete.
The elevation of the bottom of the strike off in
relation to the top of the forms is shown on an
indicator that is visible to the operator. The
equipment should be checked to make sure that the
indicator shows zero when the bottom of the strike off
is exactly even with the top of the forms.
4.4 Vibrators
When vibrators are used for full width vibration of
concrete paving slabs, they shall be internal type
either with immersed tube or multiple spuds. They
may be attached to the spreader or the finishing
machine, or may be mounted on a separate carriage.
They should not come in contact with the joint, load
transfer devices, subgrade, or side forms. Multiple
spuds should not be spaced further apart than 0.76 m
(2 1/2 feet). Therefore, a minimum of 10 are required
for a full 7.2 meter (24 feet) width paving.
Internal vibrators shall operate at 7,000 to
11,000 impulses per minute. The Contractor is
required to provide the Engineer a method to verify
vibrator frequency. Vibration is required for all
concrete pavement. Small irregular areas require
vibration by hand held or machine mounted
equipment to assure that adequate consolidation
for the full depth and width is achieved without
segregation.
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4.6 Mesh Installer
4.6.1 GeneralPavement mesh may be installed by placing it on
top of the full depth of concrete, then vibrating it into
position using an approved mesh installer. This
method eliminates the need for placing two courses of
concrete and thereby eliminates the possibility of a
plane of weakness between two separately placed
courses. Control of the placement of the mesh within
the slab has been found to be more accurate than
when placed between courses, based on
measurements of cores removed for checking
thickness requirements. Another advantage of this
method is that a bulkhead can be placed readily and
quickly in the event of breakdown since the concrete
is placed full depth, and not in two separate courses.
4.6.2 TypesTwo types of machines have been approved for
use in vibrating the mesh into position. One type
consists of a grid of steel plates approximately 4.6 m
(15 feet) in length and extending the full width of
pavement being placed. The machine which is self-
propelled is positioned over the mesh, stopped, the
mesh depressed into the freshly placed concrete and
moved ahead to repeat the operation.
The other type also is self-propelled and consists
of long tapered longitudinal runners across the width
being placed. This machine gradually depresses the
mesh into position within the fresh concrete using an
oscillating tamping motion while continuously
moving forward.
4.6.3 TolerancesSince there is a forward movement during
placing, the latter type of machine may cause
movement of the mesh across transverse contraction
joints when not properly adjusted. When using a
machine of this type, periodic checks shall be made
by uncovering the mesh
Vibrators shall be turned off when the machine
on which they are mounted is stopped.
4.5 Transverse Finishing Machines
4.5.1 Operating ConditionThe transverse finishing machine first should be
checked for its operating condition. The bearings,
especially those of the cranks actuating the oscillatingscreeds, should fit snugly so that the screed will
reverse direction without slap which would rack theforms.
4.5.2 End Plates and ScreedsThe end plates which slide on the forms should
be inspected for wear and reversed or replaced if
necessary. The screed should be checked forstraightness or crown if one is required. This is done
by placing a block on the forms under each end of thescreeds and stretching wires at both front and back
across from form to form. The crown then is checkedby measuring the offsets from the wire to the screedas outlined in 17.3. Adjusting bolts can be loosened
or tightened to secure proper adjustment.The exact tilt required in each screed cannot be
determined until construction begins. However, at thestart of paving operations the front edge of the
forward screed should be titled about 5mm (3/16inch) and the rear screed set level. Adjustments can
be made readily by end bolts provided for thispurpose.
4.5.3 StrokeSprings are used as shock absorbers to prevent
slap at the end of the stroke. These should be
checked to insure that they are in compression at alltimes. The screed lift chains must be long enough
that they are not tight at the end of the stroke or thescreed will be lifted off of the forms at every
oscillation.
Finally, the wheel scrapers should be tightened
so that they will be sure to keep the wheels clean.
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STATE OF OHIO DEPARTMENT OF TRANSPORTATION
at joint assemblies to assure that the specified
clearance of 305 ± 51 mm (12 ± 2 inches) is being
maintained on each side of the center of the joint. If
the position of the mesh is found to be outside of
tolerance, it should be corrected and the machine
adjusted at once, or its use immediately discontinued.
Production may be continued without the mesh
installer by changing to the two-course method.
Both types of machines can be adjusted to control
the depth of the mesh. Therefore, depth checks shall
be made daily to assure control of the depth of mesh.
Specifications require the mesh to be placed between
64 mm (2 1/2 inches) and T/3 plus 25 mm (1 inch), T
being the thickness of the slab, below the surface of
the pavement. When mesh is found to be outside of
tolerance, immediate adjustment shall be made.
It may be necessary to use the two-course method
at expansion joints and at abutting pavements, if the
machine with the long tapered runners cannot position
the mesh properly. The two-course method should be
employed any time satisfactory performance of the
machine is not being obtained.
4.7 Combination Float Finisher
4.7.1 TypesThe combination float finisher commonly is used
to provide the final mechanical finish on a pavement.
The machine which consists of two screeds and a
float is designed for use on a 7.2m (24 foot)
pavement.
4.7.2 AdjustmentThe front screed of the machine is a conventional
reciprocating screed which rides the forms. The rear
screed and float, however, are suspended from an
approximately 4.9m (16 foot) beam platform and do
not receive any support from the forms. The
elevation of both the rear screed and the float is
determined by adjustment of the hangers which
connect them to the platform. As a result, variations
in forms do not significantly affect the plane of
operation of either the rear screed or float. The key to
smooth finishing with this machine is the rear screed
since it is the final screeding tool and operates from a
4.9m (16 foot) straightedge essentially free from
influence of deviations in the forms.
Spring loaded shoes are fastened to both ends of
the rear screed to keep the screed in contact with the
forms. The springs are sufficiently strong so that the
rails will be kept clean, but not so strong that they
will cause the screed to raise when an undetected
highpoint in the forms is being traversed.
The float does not oscillate but moves forward
with the machine providing a smooth trowelled
surface. It is approximately 0.7m (30 inches) in
length and rides on the slab between the forms. Both
of the screeds and the float are provided with devices
which permit rapid changes in crown. These devices
make it possible to change crown at super-elevated
sections without delay. Crown is checked as
described in 4.5.2 and 17.3.
4.8 Transit Mix andCentral Mix Equipment
Before beginning paving operations and at regular
intervals during paving, concrete plants and hauling
units shall be checked for proper condition. Water
metering devices and admixture metering devices
should be checked to assure proper calibration within
specified tolerances.
4.8.1 Transit MixersTransit mixers should be checked to determine if
the counters are functioning properly. After having
been mixed for not less than 70 revolutions at mixing
speed, the mixer should contain concrete of uniform
consistency and be able to discharge the batch without
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segregation. Since this determines
acceptablility, mixers that do not perform in this
manner should not be approved, and, if encountered,
their use should be discontinued. Sources of trouble
are badly worn blades and leaky valves which prevent
mixers from producing uniform concrete. They
should not be used until corrected.
4.8.2 Central MixersCentral mixers should be checked to see that the
mixer is capable of mixing and discharging the large
volume of conrete with uniformity. During paving,
the Contractor or ready mix supplier must keep mixer
blades free from concrete build up and excessive
wear.
4.8.3 Hauling UnitsWhen the concrete is to be transported to the
paving site in dumptrucks or other non-agitating units,
these bodies should be checked to see that they are
water tight and free of objectionable corners or
internal ribs where concrete may accumulate.
Canvass covers to shield concrete from sun and wind
shall be provided when required by the Engineer.
4.9 Slip Form Pavers
Slip form pavers are generally of two basic types.
One has an extrusion meter which shapes and
extrudes the concrete pavement, while the other type
has the same features as the combination float finisher
which shapes, consolidates and then finishes the
pavement in a manner similar to conventional
methods.
4.9.1 AdjustmentThe extrusion meters or screeds and the float
should be checked for proper crown setting before
using. They should be adjusted if necessary to
conform to the typical section.
4.9.2 Tampers and VibratorsSlip form machines usually are equipped with
both tampers and vibrators. Both should be checked
to assure they are in working order before paving
starts. Vibrator frequency shall be monitored
periodically to assure the specified impulses per
minute are being obtained.
Manual of Rigid Pavement Practices
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5.0 Batch Plants
5.1 Storing Aggregate
5.1.1 Preparing SiteStockpiles should be placed on areas which are
paved, prepared by using sheet metal, wood plank,
etc., or they may be placed directly on the ground.
When building stockpiles on existing ground, the area
should be firm, cleaned of foreign material and
shaped to provide drainage. No aggregate is to be
removed from the stockpile within one foot of the
ground until the final clean up. Aggregate within this
area should be processed to meet specifications before
permitting its use.
Stockpiles should be built in such a manner that
different aggregate does not become mixed and that
the aggregate does not segregate.
5.1.2 StockpilingIn building the stockpiles of coarse aggregate,
continual care must be exercised to prevent segrega-
tion through improper handling. A clam bucket
operated by a crane of sufficient size that the center of
the pile can be reached from the edge is best for this
work. In depositing the aggregate, the bucket should
be lowered close to the level where the aggregate is to
be deposited before releasing the aggregate. This pre-
vents rolling of the larger aggregate to the bottom of
the pile to cause segregation. As the pile increases in
height, each layer of aggregate should be benched
back to form tiers that will help limit rolling and
segregation.
Other equipment may be used in conjunction with
a clam bucket.
If the Contractor uses front end loaders to build the
pile, they must have clean rubber tires if they are to
operate on the pile. As with the clam bucket, the drop
should be as little as possible when depositing the
aggregate. Once on the pile, the front end loader
should not be permitted to move on and off of the pile
as this may cause contamination.
Pushing of large aggregate as with a bulldozer is not
permitted, as this causes segregation. Use of steel treads
on the pile is not permitted as they tend to crush the
aggregate.
Small aggregate does not segregate as easily as
large aggregate because the smaller pieces are less
likely to roll down the side of the pile.
Any operation which might result in segregation,
degradation or contamination shall not be permitted.
When these conditions appear evident, a test for
gradation shall be run, and, if substantiated, the
operation shall be adjusted.
5.1.3 Scales
The specifications require that concrete materials
be measured by weight. The scales shall be checked
for accuracy with standard test weights as outlined in
the Manual of Procedures for Concrete.
5.1.4 HandlingMaterials should be placed in the batch bins by
dumping into the middle of the bin with as short of a
drop as possible. Keeping the drop to a minimum
reduces the chance for segregation in handling
aggregate, as well as in handling concrete.
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6.0 Subgrade
6.1 Preparation
After embankment has been placed and compacted
and excavation has been completed, the subgrade is
brought to the required grade, cross section and
density. The subgrade shall be checked after it has
been prepared to assure compliance with surface and
density requirements.
6.2 Requirements
The surface of the subgrade is shaped to bring it
within the allowable tolerance of the typical cross
section. The surface shall not vary more than:
1. 13 mm (1/2 inch) from a 3 m (10-foot)
straightedge applied parallel to the centerline of
the pavement.
2. 13 mm (1/2 inch) from the plan grade.
The subgrade shall be compacted to a depth of
305 mm (12 inches). Soil subgrade with maximum
dry density of 1600 - 1680 kilograms per cubic meter
(100-105 pounds per cubic foot) shall be compacted
to not less than 102 percent of maximum dry density.
All other soils for subgrade shall be compacted to not
less than 100 percent of maximum dry density.
Soils having maximum dry weights of less than
1600 kilograms per cubic meter (100 pounds per
cubic foot) are considered unsuitable for use in
subgrade and when found in the upper 300 mm (12
inches) shall be removed and replaced with suitable
soil or granular material. When these lightweight soils
are encountered and when satisfactory stability cannot
be obtained, the subgrade shall be corrected in
accordance with 203.13 of the specifications.
Detailed instructions are contained in the Manual of
Procedures for Earthwork. The surface is to be
maintained in a smooth condition to provide quick
drainage and to prevent ponding of water.
6.3 Proof Rolling
Where proof rolling is specified the compacted
subgrade shall be checked in accordance with 203.14
of the specifications. Instructions for performing this
work are detailed in the Manual of Procedures for
Earthwork.
6.4 Tolerance Check
The completed subgrade shall be checked for
compliance with the requirements of 6.2. When
checking is done the limits of the area checked should
be recorded along with a statement that the subgrade
conforms to requirements. This data should be
recorded on Form C-119 Inspector’s Daily Report,
Documentation Procedures, D-1.
Any area found outside of the allowable
tolerances must be corrected and rechecked before the
area is approved for subbase and/or pavement.
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STATE OF OHIO DEPARTMENT OF TRANSPORTATION
7.0 Subbase
7.1 General
Subbase is provided by plan for all concrete
pavements with only a few exceptions. It is possible
that there may be pavements without subbase but they
will be the exception rather than the rule. The typical
section of the plans indicates the depth and width of
compacted subbase materials. Therefore, the
Inspector should check the typical section prior to
inspecting this operation.
Stabilized subbases may be specified on selected
projects. Bituminous, cement and aggregate lime-fly
ash bases have been a design feature on several
projects. If encountered, these bases should be
constructed in accordance with contract requirements.
Cement stabilized base should meet requirements of
Supplemental Specification 804. Bituminous bases
usually are specified in accordance with 301. Plan
and Proposal Notes should be reviewed for special
requirements when stabilized subbases are required.
7.2 Placing Subbase
Subbase material conforming to the grading specified
in the plan or proposal shall be placed with an
approved spreader. The subbase may be placed in a
single lift or layer provided the compacted depth does
not exceed 200 mm (8 inches). The moisture content
will be determined from the test section. If the
material does not contain sufficient moisture when it
is spread, it shall be sprinkled with water. Care should
be exer-cised to avoid softening the subgrade when
watering.
Immediately after the subbase material has been
spread it shall be compacted until the density is at
least 98 percent of the weight obtained in the test
section. This is the minimum required for all the
subbase. Detailed instructions for the test section are
outlined in the Manual of Procedures for Earthwork.
7.3 Fine Grading
The surface of the subbase is left approximately 25
mm (1 inch) above grade after compaction has been
completed. Then, after forms have been set to grade
for form paving or the stringline is set for slipform
construction, the slight excess is removed during the
operation of the subgrader. The subgrading or fine
grading operation should result in a slight removal so
that the trimmed surface is compacted thoroughly
without low areas. Low areas require the addition of
material, compacting and regrading resulting in a
delay in progress of fine grading.
When automated subgraders are used they will
precede the setting of forms. Grade will be
maintained from a preset stringline that will be
parallel to the grade line. After final trimming the
surface will be treated the same as for conventionally
graded base.
Loose subbase material windrowed along the
inside of the forms cannot be removed by machine so
removal of this material by use of a shovel is
necessary. This shall be done before recompacting.
The trimmed surface left by the subgrader
should be compacted using a light or medium roller to
restore density to the surface. This rolling operation
also smooths the surface and reduces the friction
between the subbase and the pavement.
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STATE OF OHIO DEPARTMENT OF TRANSPORTATION
7.4 Pin Template
The surface of the subbase shall be checked using a
multiple pin template operated on the forms. The
template is to be operated behind the subgrader and
roller. Any high or low spots encountered shall be
corrected immediately, then rerolled and rechecked
before continuing.
7.5 Moisture Control
Moisture is controlled by spraying the subbase prior
to fine grading, preferably in the late afternoon of the
day before fine grading. This provides the moisture
necessary for density and provides time during the
night for uniform moisture distribution. After
removal of excess material during fine grading,
moisture is present for the final surface compaction.
Just prior to placing concrete, the subbase should be
sprinkled again to replace moisture lost by surface
evaporation so that the subbase will not absorb water
from the concrete. Loss of concrete water can result
in a rapid slump loss and early setting of the concrete
before it can be finished properly.
7.6 Rechecking Forms
The subgrader is usually one of the heaviest pieces of
equipment operating on the forms. Therefore, this is
an opportune time for the Inspector to observe the
forms for excess movement or displacement. Areas
where movement or displacement is noticed should be
rechecked for compliance with requirements before
placing concrete.
It is good practice to recheck the alignment and
grade of forms, the form locks and the pin keys after
fine grading. Some contractors assign employees to
this job. The Inspector should check these items
regardless of the Contractor’s operation to assure that
any irregularities have been corrected. Since the
paving equipment relies on the forms for support, it
cannot be expected to produce a quality riding surface
when yielding or improperly set forms are
encountered.
7.7 Recording Checks
The Inspector shall note on the Inspector’s Daily
Report, Form C-119 the limiting stations of the area
checked that conformed to the requirements.
For slipform paving, spot checks of completed
subbase should be recorded in the project records.
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Manual of Rigid Pavement Practices
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
8.0 Forms
8.1 General
Forms are a potential source of trouble because they
serve as tracks for all paving equipment, except
mixers, in addition to serving as forms for the
concrete. Since developments in paving equipment
have provided heavier equipment, the forms play an
increasingly important role in the construction of
smooth pavements.
8.2 Checking
Before any forms are set on a project they are to be
inspected to see that they comply with specification
requirements. Forms shall be not less than 3 m (10
feet) in length and have adequate joint locks for
joining ends of abutting form sections tightly. Also,
they shall have sufficient pin pockets for setting
securely so that they will withstand the operation of
the paving equipment. Forms that are found to be
distorted more than 3 mm (1/8 inch) on the top or
more that 6 mm (1/4 inch) in alignment shall be
rejected. Forms that are rejected are to be marked
conspicuously. They are not to be used unless they are
repaired so that they will comply with requirements.
Forms are reused continuously. Therefore,
inspection of forms must be continuous. Anytime
forms are found out of tolerance they shall be
rejected.
8.3 Setting
Forms are to be set true to line and grade on a
thoroughly compacted subbase with uniform bearing
throughout their entire length and width. The
building of pedestals of earth or other shimming to
bring forms to the required grade shall not be
permitted. Whenever adequate and uniform form
support is not obtained, the forms shall be removed,
the base corrected and compacted, and the forms
reset. At least three form pins are to be used in each
ten foot length. These pins shall be long enough to
hold the form in position during the placing and
finishing operations.
Grade for forms is prepared using a form grader.
A stringline is set to serve as a guide for controlling
the grade during the operation of the form grader. An
automatic subgrader operating from a preset grade
line may be used to prepare the entire width of
subbase before forms are set. If such a machine is
used, the forms may be set to correct line and grade, a
planer usually is operated on the forms to assure the
subbase is to the proper grade. Whether or not a
planer is used, a pin template shall be used to check
the surface of the subbase.
8.4 Keys and Locks
Pin keys are to be straight and free moving in the
pockets and capable of holding the forms tight against
13
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
the pins. The joint locks are not to be bent or wornand must be capable of holding the ends of the formsin true alignment. The pins and locks are checkedwhen the forms are set but should be rechecked justprior to placing of concrete and tightened ifnecessary. At the same time a final visual check is tobe made to insure forms are at proper line and grade.Smooth riding pavement with good surface finish isextremely difficult to obtain with poorly aligned and
set forms.
8.5 Oiling
The forms are to be oiled prior to placing of the
concrete. When tie bars or hook bolts are fastened to
the forms, oiling should be done prior to placing of
these units.
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Manual of Rigid Pavement Practices
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
9.0 Joints
9.1 General
Joints may be classified as transverse and
longitudinal. Transverse joints are further classified
as contraction, expansion and construction joints.
Detailed instructions for joints are found in the
specifications and in Standard Construction Drawing
BP-2.1M and BP-2.2M (BP-2.1 and BP-2.2). The
Inspector should know the requirements of the
specifications and the drawings before inspecting
joint construction.
9.2 Longitudinal Joint
Joints between adjoining lanes of pavement are
longitudinal joints. They are necessary to control
cracking in the longitudinal direction due to the
warping stresses in wide concrete slabs. Joints
between separately placed adjoining lanes are
longitudinal joints as well as construction joints. In
general the maximum pavement width without a
longitudinal joint is 4.9m (16 ft) for ramp pavements.
9.2.1 TiesTie bars or hook bolts are required to tie the
lanes to prevent them from moving apart or from
settling unevenly. Since they tie the lanes together by
bond, tie bars or hook bolts are not to be oiled.
9.2.2 PlacingBoth tie bars and hook bolts should be placed
in accordance with requirements of Standard
Construction Drawing BP-2.1M (BP-2.1). Tie bars
are 16mm (5/8 inch) in diameter, 760mm (30 inches)
in length and spaced at 760mm (30 inches). They
should be approximately at right angles and centered
at the longitudinal joint.
Tie bars may be set on chairs prior to concrete
placement or installed in the concrete after it is placed
and spread. When placed in the plastic concrete an
approved mechanical device shall be used to install
the tie bars at the proper depth and location. The
mechanical installing device shall install tie bars after
the concrete is placed to its full depth and after mesh
is in position. The device shall be located in the
paving train so as to assure consolidation of the
concrete around the tie bars.
Bent tie bars are not permitted in longitudinal
construction joints.
Hook bolts generally are used in longitudinal
construction joints. One half of the device is attached
to the form for the first lane placed. Before placing
concrete in the adjoining lane, the other half is
coupled to the embedded part. The hook bolts are to
be securely fastened to the forms so they are
positioned properly in the slab. The right angled
hooks on each side of the coupling anchor into the
slabs to provide the tie. The position of the hooks is
not important, that is, they do not have to be turned
down, up or sideways.
9.3 Contraction Joint
Contraction joints are required to be spaced in the
pavement at intervals not to exceed the maximum
spacing indicated in the Contraction Joint Spacing
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STATE OF OHIO DEPARTMENT OF TRANSPORTATION
Table of Standard Construction Drawing BP-2.2M
(BP-2.2). This type of joint is necessary to control
transverse cracking that occurs due to shrinkage and
contraction as the concrete cures and hardens.
9.3.1 DowelsLoad transfer dowels are used to transfer loads
across the transverse joints. Dowels are smooth,
round steel bars, 457 mm (18 inches) in length,
spaced at 305 mm (12-inches) intervals at mid-depth
of the pavement slab in accordance with Standard
Construction Drawing BP-2.2M (BP-2.2). All dowels
used in concrete pavement are to be epoxy coated as
per 709.13. The entire dowel including the ends is to
be epoxy coated.
To function properly dowels should be parallel
to the surface and parallel to the centerline of the
pavement since expansion and contraction movements
occur in this direction. To assure proper alignment of
dowels, a cage or basket is used. This, together with
the dowels, is called a dowel assembly. Dowel
assembly wires as well as the dowel are required to be
epoxy coated according to 709.13 of the CMS.
The diameter of the dowel required in the
pavement depends on the pavement thickness. Unless
otherwise specified in the plan the dowel diameter
required is to be as shown in the Dowel Size Table
of Standard Construction Drawing BP-2.2M
(BP 2.2).
9.3.2 Placing AssembliesAssemblies are to be positioned not to exceed
the maximum spacing and must be perpendicular to
the centerline and forms. Spacing may be controlled
by measurement along the forms. Locating the
transverse alignment may be by any method that
assures a right angle to the centerline. On curves the
joints should be approximately on radial lines.
After the alignment is established, a string line
stretched between forms will assist in placing the
dowel assemblies properly. Transverse contraction
and expansion joints must be continuous across the
full width of pavement placed. Therefore the line of a
joint in a lane already placed must be continued in all
other adjoining lanes.
When properly located and placed, joint
assemblies are anchored in place. At least eight 13
mm (1/2-inch) steel pins 460 mm (18 inches) in
length are required to hold each 3.6 m (12 foot) unit.
The pins are driven at an angle to brace the assembly
from lateral movement and to prevent vertical
displacement when concrete is placed. Two of the
pins are driven opposite each other at each end of the
assembly, and the remaining four are driven in a
staggered pattern on each side. Care must be taken to
avoid hitting the assembly when driving the anchor
pins. If wires of the basket are bent, the dowels may
be thrown out of line and require the entire assembly
to be rejected unless it can be removed, straightened
and reset properly. Any assembly badly distorted
should be rejected. The epoxy coating must not be
damaged during the above operation.
If concrete pavement is placed on an existing
pavement or stabilized base, the bowel baskets shall
be held firmly in position by use of a power driven
fastener and an appropriate clip at 6 locations along
the assembly (3 on each side of the assembly). The
clips shall secure the basket from lateral and vertical
displacement during concrete placement.
If the assembly is placed on a subbase consisting
of sand, a minimum of six steel bearing plates
approximately 127 mm (5 inches) square shall be
placed under each 3.6 m (12-foot) assembly unit.
Bearing plates also are required when any subbase
material is used which permits distortion or settlement
of the assembly due to poor stability. One bearing
plate is to be used with each of the four end anchor
pins with the others spaced uniformly along the
assembly. Shimming with pebbles, stones, etc. shall
not be permitted. If shimming is necessary, it is
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Manual of Rigid Pavement Practices
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
obvious either that the subbase is not prepared
properly or the dowel assembly is bent or misaligned.
In either instance, the subbase or assembly shall be
rejected until corrective action has been completed.
Specifications provide that dowels may be placed
in the full thickness of pavement concrete by a
mechanical device approved by the Engineer. If the
Contractor contemplates this method of installation
special instruction should be requested from the
Construction Section of the Office of Highway
Management through the District Construction
Administrator. This method of dowel placement has
been used successfully for many years in construction
of plain concrete pavements. It is intended to permit
this method provided the Contractor is able
continuously to install dowels properly.
Loose dowels are placed on an installing rack of a
self-propelled machine and installed by vibrating
them into the plastic concrete. After the dowels are
placed at mid-depth, the rack is withdrawn leaving the
dowels in position supported by the concrete. The
dowels are to be installed after the concrete is placed
to its full depth and after the mesh is positioned
properly. The only operations permitted after
positioning the dowels are machine and hand
finishing of the surface of the concrete.
9.3.3 Preventing BondFor dowels to function properly in the concrete slab,
they must be oiled with a thin coating of oil for at least
one half their length to prevent the concrete from
bonding to them. Most of the dowel assemblies have
one end of the dowel welded to the basket wire. It is the
free end opposite the welded end that must be oiled.
Dowels shall be oiled the same day that they are to be
covered with concrete. Care should be exercised to see
that at least half the dowel is covered completely. It is
always better to oil more than half the length of each
dowel to be certain that bond is prevented so that the
joint will function properly.
Epoxy coated dowels should be inspected to
assure the coating is continuous on the ends and
lateral surface of the dowel and that the coating is not
perforated, cracked, or otherwise damaged, in which
case it shall be rejected. In addition, the coating shall
be free from holes, voids, contamination, cracks, and
there shall not be more than two holidays (pinholes
not visually discernable) in any 305 mm (12 inch)
length of the coated dowel. The free ends of the
dowels shall be free of burrs or projections.
9.3.4 TiesAfter assemblies have been set and anchored
properly, the shipping ties or clips used to hold both
halves together during shipping and handling must be
cut. The shipping wire is normally cut at two
locations and removed immediately prior to placing
the concrete. The ties are usually a small diameter
wire hooked or tack welded to the basket assembly wire.
9.3.5 Checking AssembliesAfter being set, anchored and oiled the dowels are
to be checked to assure that they are parallel to the
subbase surface and the centerline of the pavement.
Spot measurement checks of the distance between the
dowel and the forms, made at each end of the dowel,
provides a check for being parallel to centerline. The
distance to each end of the dowel must be equal for
the dowel to be parallel to the forms and the
centerline. After some experience, this check can be
a visual check since dowels out of alignment stand
out when observing them in relation to the forms.
An adjustable A-frame level is used to spot check
several dowels in every assembly unit to assure that
all dowels are parallel with the surface of the
pavement. The level first is placed on the forms or
subbase adjacent to a basket assembly. Then the level is
placed on the dowels. The bubble will indicate level if the
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Chapter 9.0: Joints
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
dowel assembly is set properly and is parallel to the
surface of the pavement. At least three dowels are to
be checked in each 3.6 m (12-foot) section, one at
each end and at the middle. If the dowels are not
parallel with the surface when checked, the assembly
must be adjusted and rechecked. If proper alignment
cannot be obtained, the assembly must be removed
and replaced.
Immediately prior to paving, shipping wires are
to be removed. Shipping wires run the same direction
that the dowels do through the joint.
9.4 Expansion Joint
Relief for compression stresses in hot weather is
provided at bridges and at intersections. This relief is
in the form of expansion joints. Nonextruding
compressible material is placed in the transverse joint
so that expansive forces can be relieved by the
compressible material. Standard 460 mm (18 inch)
long epoxy coated dowels are required for load
transfer, in all expansion joints. Damage to bridges
and abutting concrete is averted by the use of
expansion joints. The expansion joint also permits
contraction movement in addition to absorbing
excessive expansion. Proper size dowel holes shall be
punched or drilled into the preformed expansion joint
filler in order to insure a tight fit when the dowel is
pushed through it.
9.4.1 Expansion MaterialPreformed compressible material 25 mm (1 inch)
thick is installed in a dowel assembly at the location of
the expansion joint. It must be set perpendicular to the
top of the expansion forms as well as perpendicular to
the line of forms and the pavement centerline. The
material must extend down to the top of the subbase
and to the side forms so that free movement is allowed
throughout the entire joint. The top of the expansion
material is held 25 mm (1 inch)below the surface. It
will be permissible to place the expansion material
closer to the surface to facilitate sawing of this joint,
provided all material is removed to a depth of 25 mm
(1 inch). This area shall be sealed using a hot applied
joint sealer meeting the requirements of 705.04
(ASTM D-3405).
9.4.2 CapsA cap is placed on the free end of each dowel to
create a void in the concrete to permit expansion
movement. This cap must be placed on the free end
after the dowel has been oiled. The cap contains a
crimp to position it to provide for the 25 mm (1-inch)
void. These caps must not be forced beyond the
crimp or there will not be space for expansion and the
joint will not function correctly.
9.5 Construction Joint
Construction joints are transverse bulkheads placed at
the conclusion of each day’s paving or when
production is interrupted for more than 30 minutes.
These joints are formed by using an adequate
bulkhead that will provide a straight joint. The
bulkhead shall have openings provided for individual
dowels or an assembly of dowels. The bulkhead must
be shaped to conform to the typical section of the
pavement.
Construction joints may be located at contraction or
expansion joints in concrete pavement but shall not be
located closer than 3.0 meter (10 feet) to any other
parallel joint. In plain concrete pavement or base, they
shall not be closer than 1.8 m (6 feet) to another
transverse joint.
9.5.1 DowelsSmooth epoxy coated dowels shall be used in
construction joints and care should be exercised in
placing them parallel to the surface. The dowel size
shall be as required for the contraction joints in the
adjoining pavement. For pavement lanes of even 0.3
m (foot) width increments, dowels will be spaced at
300 mm (12-inch) centers beginning 150 mm (6
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Manual of Rigid Pavement Practices
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
inches) from the longitudinal joint. Where other
widths are specified, the spacing between the end
dowel and the outside edge of the lane may be
increased up to 300 mm (12 inches). A dowel shall
be placed 150 mm (6 inches) from the outer edge of
the pavement when the spacing between the end
dowel of the basket and the outside edge exceeds 300
mm (12 inches).
At skewed joints between approach slabs and
approach pavement, care should be exercised to
position the dowels parallel to the centerline. Recent
experience indicates movement occurs at such joints.
Provision should be made for this movement by
placing dowels the same as for contraction joint.
The joint may be hand formed or sawed to the
same dimensions required for transverse joints in
adjoining pavement.
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Chapter 9.0: Joints
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
10.0 Sawing and Forming Joints
10.1 General
Sawing of joints has resulted in improvement in the
riding quality of concrete pavements and higher
quality concrete in the joint area. With sawing, the
concrete is placed and finished in a continuous
operation without disturbing the surface at every joint
for hand forming a groove. In lieu of this laborious
hand operation, the groove is sawed in the hardened
concrete after the surface has been machine finished
and has hardened sufficiently to saw. The uniform
groove thus created, controls transverse cracking and
provides a reservoir for the joint sealer.
Sawing is required for all contraction joints.
Expansion joints may be sawed or hand formed. See
451.08(c). Longitudinal construction joints either
may be hand formed or sawed. When properly done,
sawing produces uniform joint openings and,
therefore, is preferable.
10.2 Requirements
Joint openings are to be constructed in accordance
with the requirements of Standard Construction
Drawings BP-2.1M and BP-2.2M (BP-2.1 and BP-
2.2). Contraction joints are sawed in a progressive
manner as soon as possible without causing excessive
raveling of the concrete. Slight raveling is not
objectionable but rather is an indication that sawing is
being done at the proper time.
The timing of the sawing operation is critical for
contraction joints. Sawing must be done after the
concrete hardens sufficiently to support the sawing
equipment and to avoid spalling and raveling. This
operation cannot be tied to normal working shifts but
must be accomplished when the concrete is ready. A
standby saw is required at the paving site in the event
of breakdown or inability of one machine to maintain
necessary progress.
Inspection should include random checking of
each day’s sawing to assure the width and depth
specified is attained. Saw blades will wear with use
so continued checks must be made.
Since the timing of sawing is of utmost
importance for contraction joints, it should be
emphasized, and inspectors assigned to this operation
must be aware of this importance. However, the
control of sawing is the Contractor’s responsibility
and the Inspector should avoid making decisions as to
when to saw.
Timing of the sawing of longitudinal joints is
not as critical. However, specifications require the
sawing to be done within three days after concrete is
placed.
Sawing may be done wet or dry, and the cut
must be cleaned by a jet of water, if sawed wet, or air
under pressure, if sawed dry.
10.3 Contraction Joint
Contraction joints in pavements 255 mm (10 inches)
thick or less shall be sawed to a minimum of 1/4 of the
pavement thickness and to a width shown in the
standard, measured at the time of sawing. For
pavement that is greater than 255 mm (10 inches) thick
20
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
the sawing depth shall be 1/3 the slab thickness. A
tolerance of ±1.6 mm (1/16 inch) is allowed in the
width of the saw cut.
The depth of 1/4 or 1/3 the pavement thickness
is the minimum necessary to control transverse
cracking. Following this initial sawing the Contractor
must saw to the width and depth detailed in Standard
Construction Drawing BP 2.2M (BP-2.2). This
additional sawing is necessary to install the preformed
elastomeric compression joint seal.
The width of the saw cut must be controlled to
within the tolerance to create a uniform width opening
necessary for the installation of the joint filler. The
filler is designed to function within the width
specified, and any variation may affect its
performance and create installation problems.
If the Contractor desires, sawing may be
accomplished in two operations provided:
1. The first operation consists of sawing to the
minimum depth specified using a 6 mm ± 1.6
mm (1/4 inch ± 1/16 inch) blade.
2. The second operation consists of sawing to the
specified depth using a blade of a width within
the specified tolerance. The second sawing is to
be performed when the temperature is 21° C
(70F) or above.
This method provides relief when critical sawing
conditions exist and provides a uniform width opening of
desired width for installation of joint seal. Use of a
narrow blade permits sawing earlier to avoid random
cracking. Any raveled edges are dressed during the
second sawing.
10.3.1 Random CracksIf a crack appears ahead of the machine during
sawing, it is an indication that sawing is late. When
such cracking is noted, sawing of that joint is to be
stopped immediately and the saw moved ahead several
joints. Saw a joint, move ahead several more joints,
and saw another joint. Continue skipping three or four
joints and sawing every fourth or fifth joint until
sawing is back on schedule. The presence of slight
raveling indicates proper timing of sawing. When
back on schedule every joint should be sawed in
order. After sawing has been completed for the day’s
production the saw can be returned to saw the joints
skipped. The standby saw may be pressed into
service to saw the joints skipped if an experienced
operator is available.
This procedure of skipping ahead and sawing
every fourth or fifth joint relieves the stresses that
occur when the concrete hardens and shrinks during
curing. Once these stresses are relieved the sawing of
the in-between joints is not as critical but should be
done as soon as possible.
The pavement normally is subjected to
expansive forces the following day when the
temperature rises. When temperatures drop the
evening of the following day, the pavement again
experiences shrinkage stresses and all joints originally
bypassed must be sawed before these stresses result in
random cracking.
Pavement placed should be sawed the same day,
possibly six to eight hours after placing. Concrete
placed late in the day may not harden to permit
sawing until the next day, but sawing must be
completed before the following late afternoon
temperature change as shrinkage will again occur as
temperatures drop.
Joints in lanes placed adjacent to a previously
placed lane that are tied together must be sawed as
soon as possible to prevent uncontrolled cracking. If
a new lane is tied to existing concrete that is
expanding and contracting with changes in
temperature, stresses will be transmitted to the new
slab unless joints are sawed as quickly as possible.
The following provisions are important to obtain
quality sawed joints in these areas:
1. All transverse joints, except construction joints
in the second lane of pavement shall be opposite
and in line with those in the first lane.
2. The sawing of the joints shall be done as soon as
the saw can be operated on the pavement without
21
Chapter 10.0: Sawing and Forming Joints
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
damaging the surface or without raveling of the
newly cut joint.
3. Joints opposite those in the first lane placed
where movement is indicated by cracking, shall
be sawed first.
4. The cut is to be made from the old slab to the
outside or open edge of the new slab being
sawed.
A sudden drop in temperature, a wide range
between day and night temperatures or a cold rain
creates additional problems when sawing contraction
joints. These conditions add stresses due to thermal
changes to the shrinkage stresses and make the timing
of sawing doubly critical. When these conditions
occur or are anticipated increased attention must be
given to the sawing operation to assure control of
cracking.
10.4 Longitudinal Joint
Longitudinal joints shall be used when called for in
the plans on the typical sections and shall be
constructed in accordance with Standard Drawing BP
2.1M (BP 2.1). Tie bars shall be 16 mm (5/8 inch)
diameter, round, deformed steel, 760 mm (30 inches)
long and spaced at 760 mm (30 inches) center. Tie
bars can be supported on chairs, or they may be
installed by a mechanical installing device. Bent tie
bars are not permitted. The longitudinal joint
between adjoining slabs poured in separate operations
shall be a butt joint with hook bolts or tie bars unless
otherwise shown on the plan as untied. Expansion
anchors, if used, shall be installed per manufacturer’s
recommendations and the hook bolt screwed into the
anchor.
In pavements 255 mm (10 inches) or less sawed
longitudinal joints between adjoining lanes placed at
the same time shall have a minimum depth of 1/4 of
the pavement thickness. In pavements greater than
255 mm (10 inches) the depth of sawing shall be 1/3
of the pavement thickness. The width shall be
approximately 3 mm (1/8 inch). The minimum depth
is necessary to control cracking due to warping
stresses. The width of this joint is not critical except
that it should be uniform for ease in sealing.
The longitudinal joint between separately
poured lanes may be sawed or formed. If formed, an
insert 25 mm (1 inch) minimum in depth and tapered
9.5 mm (3/8 inch) at the top to 6.5 mm (1/4 inch) at
the bottom must be inserted into the plastic concrete
to form a void for the joint filler. The insert must be
placed carefully against the existing concrete at the
proper depth. When the concrete has set, the edge of
the plastic concrete is rounded using an edger of the
specified radius. The insert must be removed
carefully at the proper time, and the groove should be
tooled with an edger if necessary.
In lieu of hand forming, the concrete may be
placed without an insert and then carefully edged
using an edger having a 3 mm (1/8 inch) radius. This
edging creates a line for sawing the groove at a later
time. This joint is formed for its full depth.
Therefore, the time of sawing and depth of saw cut is
not critical.
In lieu of using a form or hand tooling the
longitudinal joint in separately placed lanes, the joint
can be sawed. The saw cut, however, should have a
minimum depth of 13 mm (1/2 inch) and a minimum
width of approximately 6 mm (1/4 inch).
When edging the longitudinal joint, an edger
having a 3 mm (1/8 inch) radius shall be used as
compared to a 13 mm (1/2 inch) radius edger required
for the outside edge of pavements.
10.5 Expansion Joint
Expansion joints are required adjacent to bridge
approach slabs at distances of approximately 6 m (20
feet) and 18 m (60 feet). Expansion joints may also be
detailed in the plan at other locations. All expansion
joints are dowelled and allow for the pavement to
22
Manual of Rigid Pavement Practices
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
expand or grow due to temperature variations. A
standard expansion joint allows for 25 mm (1 inch) of
expansion.
If the pavement consists of two or more
separately placed lanes, the expansion joints shall be
a continuous straight line for the full width of the
concrete pavement, including concrete shoulders. All
expansion joints are perpendicular to the centerline
unless adjacent to skewed approach slab.
Inspectors shall assure that the 25 mm (1 inch)
thick expansion joint filler is held rigidly in position
and extends full width of all lanes. The expansion
joint filler shall be the required height and shall
extend to the top of the subbase (or bottom of the new
pavement) so that no concrete is permitted to flow
under it. Holes in the expansion joint filler shall be
neatly punched or drilled and the dowels shall fit
tightly through with no gaps in which concrete could
flow. The free end of each dowel (the end not welded
to the basket wire) shall be oiled with a bond breaker
and the expansion sleeve attached immediately prior
to placing the concrete. The expansion sleeve is
required to allow the dowel to slide a distance of 25
mm (1 inch) inside of it.
The Contractor must provide adequate
consolidation throughout the slab depth adjacent to
the joint filler and around dowels.
10.6 Construction Joint
Construction joints are built at the end of each day’s
work or whenever it is necessary to suspend work for
more than 30 minutes. Construction joints in all con-
crete pavements are to be dowelled and perpendicular
to the centerline. Construction joints may be located
at a contraction joint or between contraction joints.
Construction joints are to be formed with a
straight bulkhead with openings provided for dowel
bars and spaced as detailed in the standard drawing
for transverse pavement joints. Construction joints in
reinforced pavement (Item 451) may be located at a
contraction joint or between contraction joints,
provided that they are not closer than 3.0 m (10 feet)
to another parallel joint. In plain concrete pavement
or concrete base (Item 452 or 305), a construction
joint shall not be closer than 1.8 m (6 feet) to another
parallel joint. Construction joints in all concrete
pavements shall be sealed as detailed in the standard
drawing for that type of pavement.
10.7 Checking
The Inspector occasionally should check the width
and depth of joint groves for conformance with the
requirements discussed in this section of the manual.
Special attention should be given to checking depths
of sawed longitudinal joints between lanes placed at
the same time. The limits of areas checked should be
recorded on Form C-119, Inspector’s Daily Report,
for filing in the project records.
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Chapter 10.0: Sawing and Forming Joints
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
11.0 Reinforcement
11.1 Purpose
Distributed steel or reinforcement used in highway
pavements generally is in the form of welded wire
fabric or mesh. Its principal function is to hold
together the fractured faces or slabs after cracks have
formed. Adequate load transmission across the crack
is thus assured, and the infiltration of incompressible
material into the crack is prevented. It does not
increase the flexural strength of an unbroken slab.
Like tie bars, steel mesh is designed to withstand
tensile stresses and hold the slab together.
11.2 Handling
Mesh usually is delivered to the job in advance of
paving operations and stored. It should be carefully
stacked and kept clean. Before it is used it should be
inspected to see that it is free from dirt, oil and mud,
which will destroy bond with the concrete, and that it
has not been damaged in shipment or in storage. Any
mesh which has been bent or has welds that have been
broken, should be rejected. If the mesh is repaired, it
should be rechecked before using.
Mesh with rust, mill scale or a combination of
both shall be considered satisfactory provided the
minimum dimensions are not less than specified.
Recent research indicates that tight, scaly and pitted
rust does not prevent bond, but actually improves it.
Therefore, mesh should not be rejected for
rusting unless the rust is so severe that the wire
dimensions are reduced to less than the minimum
specified. The longitudinal wire is designated as a
MW55 or MD55 (W8.5 or D8.5) size and has a
nominal diameter of 8.4 mm (0.329 inch). An MW26
or MD26 (W4 or D4) wire is used transversely and
has a nominal diameter of 5.7 mm (0.225) inches. If
it is suspected that the wire dimensions have been
reduced, the District laboratory should be requested to
check the wire dimensions with a micrometer.
11.3 Condition of Mesh
If mesh is placed along the rough grade or the
shoulder so as to be convenient to the paving
operation, it should not be done so far in advance that
mud will accumulate on it. Care should be taken to
prevent the mesh from becoming badly bent.
If a mesh cart is used on the forms behind a
spreader, the mesh is stacked in piles of the size
carried on the cart at intervals along the grade. These
stacks should be placed on wood blocks or in some
manner kept from becoming caked with mud from the
grade.
11.4 Placing
If the pavement is being placed in two courses, the
concrete for the base layer should be distributed
uniformly on the subbase and then struck off by means
of a mechanical template to the proper depth. The
normal strike off is from 64 mm (2 1/2 inches) to T/3 +
25 mm (T/3 + 1 inch) below the finished surface
(where T is the thickness of the pavement). The strike
off should leave a plane table without voids or high
spots on which to place the mesh. Concrete shall be
24
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
placed and struck off uniformly to permit placing of
mesh to specified depth without manipulation.
If the mesh is bent, it should be straightened
before it is placed or if it has a gradual bow place it so
the concave side is down. Workers placing steel must
not track mud or dirt into the concrete.
11.5 Tieing
The mesh is to be placed between the forms leaving 50
mm (2 inches) between the ends of the wires and the
side forms, pavement edge, or centerline of pavement.
Reinforcing mesh is normally shipped in lengths of 5.9
m (19 feet) by 3.6 m (11'-8") wide which will fit the
specified joint spacing of 6.5 m (21 feet) for reinforced
concrete pavement with an allowance of 300 ± 50 mm
(12 ± 2 inches) from the center of each transverse
joint. If shorter lengths are provided, transverse laps
shall be 305 mm (12 inches) and mesh sheets shall be
fastened at the edge of the lane and two other
locations.
Usually, mesh is not fabricated for lane widths
greater than 3.6 m (12 feet). Therefore, when placing
pavement lanes in excess of 3.6 m (12 feet) in width it
will be necessary to tie additional mesh to the
standard width sheet. This may be done by tieing
together the outer longitudinal wire of adjacent
sheets. A minimum of four ties should be placed
along the overlapped longitudinal wires to hold the
two sections of mesh in the same plane until the
concrete sets.
If the screeding operation has been done
properly and the mesh placed in flat sheets and tied
properly, there will be no difficulty from the steel
working up into the finishing operations.
25
Chapter 11.0: Reinforcement
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
12.0 Moisture and Mix Control
Instructions for controlling the proportioning and
mixing of concrete are contained in the Manual of
Procedures for Concrete. The Inspector should
review its contents so that he is familiar with the
details of the production and delivery of concrete for
use in pavements.
26
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
13.0 Placing and Spreading
13.1 Placing on Grade
Concrete is to be deposited upon the subbase evenly
in a manner that requires a minimum of redistribution.
Even distribution of concrete on the subgrade, or in
each course being placed, is the first step toward an
acceptable job.
13.1.1 Importance of Uniform SpreadThe most even distribution in initial placing will
result in minimum variation in final settlement of the
surface. If concrete is deposited in piles, or
windrows, unequal consolidation may take place
before finishing operation are begun. This never will
be overcome throughout the finishing procedure and
can be the cause of unequal settlement and rough
surfaces after finishing has been completed.
In case of transmit mixer or dump truck
delivery, methods of discharging shall be used that
will spread each batch as evenly as possible. Better
results are obtained when a hopper-type spreader is
used with concrete delivered to the site either with
transit mixer or dump truck.
13.2 Spreading
13.2.1 When RequiredAn approved spreader must be used whenever the
pavement being placed in one operation is 3.6 m (12
feet) or more in width and the amount to be placed
exceeds 8300 m²(10,000 square yards). Concrete
spreaders are powerful pieces of equipment and will
handle heavy accumulations of concrete. However,
this is not reason to permit improper distribution.
13.2.2 HeadThe initial placing of the concrete should be just
enough so that a slight excess is carried ahead of the
spreader as it levels the concrete to a uniform surface
or, in case a spreader is not required, the concrete can
be spread and leveled easily with shovels. Unless this
is done there will be irregular surge past the strike off
of the spreader or past the finishing screed.
This will necessitate excessive manipulation of
the surface in order to obtain specified smoothness
requirements. Excessive manipulation tends to alter
the quality, durability and wear resistance of the
finished pavement.
In addition to these principal precautions in
placing operations, there are some others that should
be observed. Workers should not track dirt or other
debris into the concrete, nor should they walk
unnecessarily on the fresh concrete after it has been
struck off. Boot tracks often are filled with mortar
which will shrink when setting, which may develop
into low spots. Foreign material must be kept out of
the concrete. The incorporation of such items in
concrete also will cause defects in the pavement.
13.2.3 Care at JointsConcrete should be shoveled in place around
expansion joint assemblies. The concrete should not
be dropped directly on joint assemblies from the
delivery equipment but should be gradually spread
27
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
over them by the spreading machines. If a
hopper type spreader is used, it should not be
positioned over the joint assemblies while concrete is
being discharged. This could result in displacing the
dowel assembly or dowels.
13.3 Vibration
Internal vibration is required for consolidating concrete
for the full width of pavement placed. If internal
vibration is attached to the paving machine, separate
vibration along the forms and around contraction joint
assemblies is not required. However, separate
vibration around expansion joint assemblies and
construction joints shall be a requirement in fill-in
areas not traversed with such equipment. Regardless of
the method of consolidation used the vibration must
be shut off when the machine stops. If it is permitted
to run, rapid segregation of the concrete composition
can occur which may cause weak spots in the slab.
Also, this practice may cause the vibration action to
be picked up by each dowel and result in water planes
and/or soft weak mortar being formed along each
dowel. This seriously reduces the strength and ability
of the concrete to absorb the bearing stress which
each dowel transmits to the concrete under traffic
load, and contributes to early faulting of the joint.
The Contractor is to provide the Engineer a
tachometer or other frequency measuring device to
verify the vibration frequency. The vibration
frequency shall be maintained between 7,000 and
11,000 impulses per minute.
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Manual of Rigid Pavement Practices
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
14.0 Operation of Transverse Finishing Machine
14.1 Work to be Performed
The work of the transverse screed is an intermediate
step in the process between placing and distribution
of the concrete and the final mechanical finishing.
The work performed by the screed should be as nearly
complete as is possible, so that the operation by any
following equipment need be only a smoothing and
floating process.
As the transverse screed begins work, the
concrete before it must be distributed to
approximately the correct surface level, either by
mechanical concrete spreaders or by hand methods.
The requirements for correct operation of the
transverse screed are the same regardless of the
method of prior distribution, except that local grading
by hand work will be more irregular and will require
more care in the screeding operation.
14.2 Result to be Obtained
The transverse screed must leave the surface with a
uniform texture and screeded to a uniform, correct
elevation for final finishing. If the screed does not
perform this function, good finish cannot be obtained.
Deep or irregular corrugations behind the screed
indicate improper operation.
14.3 Factors Involved
Satisfactory results of operation of the transverse
screed depend upon several critical factors. These
factors must be considered at all times, and variations
in the adjustments or in the operation of the screed
must be made, as occasion demands, to keep the
factors always in balance.
14.3.1 Head-Front ScreedThe head of concrete carried in front of the
forward screed must be maintained at uniform
heights, 100 to 250 mm (4 to 10 inches), and in
uniform quantity across the full width of the lane.
14.3.2 Head-Rear ScreedThe head of concrete carried in front of the rear
screed must be uniform and about 50 to 100 mm (2 to
4 inches) high. The material being moved ahead by
the rear screed should roll, not flow or tear, and the
mix and timing of operations must be controlled to
satisfy this requirement.
14.3.3 Height and TiltThe height and tilt of the screeds must be
adjusted to compact the particular mix being used and
to permit a uniform amount of surge.
14.3.4 Traction Speed and StrokeThe traction speed, screed speed, and length of
screed stroke are controlled independently. They
must be combined in the proper relation to obtain
optimum results. As conditions on the project vary,
these relationships should be varied to produce a
constant quality of result.
14.3.5 Clean RailsThe forms and wheels must be kept clean. If the
wheels ride on an irregular surface, the concrete will
29
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
show corresponding roughness. The screeds
must be kept clean, so that they do not leave streaks in
the concrete and do not drop lumps of hardened
concrete on the fresh surface.
14.3.6 SurgeThe amount of concrete being carried ahead of
the screeds (both forward and rear) controls the
amount of surge past the screeds for any given mix. If
the head of concrete is too high, an excess will pass
under the screed and an overload will be left for
following equipment. If there is a deficiency of
concrete at any point in front of the screed, a low spot
will develop at that point. If the head varies
continually, the surge will also vary and a wavy or
rough surface will be left. Therefore, a uniform roll
of concrete must be maintained along the front edge
of the screeds to provide a uniform amount of surge.
At the beginning of a day’s work there should be a
small amount of concrete placed in front of the
forward screed to provide a working supply for filling
in low areas. As the work progresses, this
accumulation should not be allowed to build up, but
should be maintained uniformly. If excess builds up,
the excess should be screeded off or a second pass
made.
14.4 General Operation
The Inspector should insist that the work of distribution
and the work of the transverse screeding be
coordinated to give continuous, acceptable results. The
forward screed should compact the concrete without
excessive surge. The rear screed should cut the
concrete off at the top of form level, allowing for a
very small amount of settlement which usually occurs
before the following finisher passes. The difference in
the requirements at the two screeds accounts for the
difference in the size load each should carry.
14.5 Passes Necessary
If one pass of the screed does not result in satisfactory
surface conditions, a second pass is necessary. It is
preferable that preceding operations be controlled so
that a second pass is not required at intermittent
points. If the Contractor elects to use two screeds or
to pass over the entire area twice with one machine,
such a procedure is acceptable. Different amounts of
screeding will result in variable surface conditions
and are to be discouraged.
14.6 Effect of Mix Consistency
Screeds always should work with the screed wearing
plates working directly on the forms. A straight
screed with no tilt will result in a concrete surface at
or below form level, except for surge. Adjustments in
the elevation and tilt of the screeds may be required to
work certain mixes properly. If the mix is extremely
stiff the screeds normally will tear the surface and
leave insufficient mortar for finishing. Under these
conditions the front or first screed should be tilted so
that the forward edge is raised slightly. This will
compact the concrete as the screed passes and force a
small amount of mortar to the surface. With
extremely stiff mixes there likely will be an absence
of surge which, with combined tearing, leaves the
surface below the top of forms. The center of the
screed then should be raised slightly by adjusting end
screed hanger bolts, leaving the end plates to work on
the forms with the remainder of the screed raised.
This will permit the required amount of concrete to
pass the forward screed. The rear screed always
should be straight along the rear edge and work
directly on the forms.
The amount of tilt of the screeds must be worked
out for the particular job conditions. As a starting
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Manual of Rigid Pavement Practices
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
guide, the following information will be of assistance.
With standard Portland cements and with air
entrained concrete of relatively stiff consistency, less
than 50 mm (2-inch slump), the forward screed likely
will require a tilt of 6 mm (1/4 inch) or less and the
rear screed a tilt of 0 to 2 mm (1/16 inch).
14.7 Relation-Traction of Stroke
The combinations of traction speed and screed motion
to be selected depend on the concrete mix and
consistency and upon the grade or super elevation of
the pavement. With stiff mixes, the screed speed
should be rapid with a long stroke and the traction
should be slow in comparison to more workable
mixes. This provides extra working of the concrete
and will aid in compaction and in providing enough
mortar at the surface for finishing. With more fluid
mixes, the screed action should be decreased, both in
speed and length, and the traction speed should be
increased. This will prevent over working or
excessive agitation of the concrete which might cause
flowing to the low side of the forms, excessive surge
past the screeds or a pooling of wet mortar on the top.
The relation of traction and screed speeds is very
important. In most machines, the controls are
independent and the choice of proper combination can
be made by trial without any difficulty. A change in
speed of either screeds to reaction requires only
shifting of a lever. The change of length of screed
stroke requires a stoppage of work and readjustment
of the screed drive, but this change should not be
required very often unless control of the concrete mix
is poor. Poor control of the concrete mix should not
be tolerated.
14.8 Wearing Plates
The screed wearing plates are rubbing continuously on
the forms or on completed concrete lanes. They are
made of abrasion resisting steel, but may wear rapidly
under the heavy punishment they receive. As they
wear, they have the effect of lowering the entire
center portion of the screed by the amount of wear.
Furthermore, the wear may not be the same for the
full length of screed stroke, and may vary the strike
off elevation of the screed. They should be checked
at the beginning of each job. Adjustments for up to 3
mm (1/8 inch) in wear can be taken care of by
adjusting the screed bolts. When wear exceeds this
amount, the plates should be replaced.
14.9 Care at Expansion Joints
Care should be exercised when operating the finishing
machine over expansion joints to avoid displacing or
damaging the preformed expansion material. Any
method of operation that does not interfere with the
expansion material will be permitted.
14.10 General
Inspectors on transverse screeding work must
remember that the finishing machine is not intended
for heavy duty. The surface left by this work must be
uniform and satisfactory. The ability of the transverse
screed to provide these requirements is available in
the machine. The Inspector should insist that the
operator make full use of the capabilities of the
machine in order to obtain a complete and proper
integration with the entire paving process.
31
Chapter 14.0: Operation of Transverse Finishing Machine
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
15.0 Operation of Combination Float Finisher
The combination float finisher serves both as a
conventional transverse and longitudinal finisher.
The transverse screeding is accomplished through the
two screeds (front and rear) and the longitudinal
finishing by the suspended finishing pan which rides
on the slab surface.
All phases of good construction practice must be
followed in order to obtain the best finish. Several
points, however, must be adhered to closely in order
that the best possible finish will be obtained when the
machine is used for the final mechanical finishing
operations. These items are described in the
following sections.
15.1 Metering Concrete to Machine
The concrete must be accurately metered to the
machine. Better results are obtained when spreaders
and auxiliary screeds (when used) operating ahead of
the machine leave just enough concrete so that a
uniform roll of 100 to 150 mm (4 to 6 inches) is
carried on the front screed. When this condition does
not exist, the equipment operating ahead of the float
finisher should be adjusted so that such a concrete roll
is obtained.
15.2 Setting Screeds and Float
The screeds and float must be set accurately. Both
front and rear screeds should be set flat. When the
front screed is flat and carries a 100 to 150 mm (4 to 6
inch) roll, it passes sufficient concrete to form about a
50 mm (2-inch) roll on the rear screed. When this 50
mm (2-inch) roll reduces in size, fresh material should
be carried back and placed so that a uniform roll is
obtained. It is essential that the roll in front of the
rear screed be kept uniform for optimum results.
The rear screed cuts off any excess concrete and
leaves the pavement surface at the desired crown and
grade. When set to proper crown without tilt, the
float just makes contact with the surface which it
trowels smooth and free of screed marks.
Occasionally, it is desirable to leave the front of the
float about 2 mm (1/16 inch) when greater
compaction is desirable. This practice, however,
generally leaves deeper transverse marks than are
considered desirable.
15.3 Adjust to Proper Speed
15.3.1 One Pass OperationThe finishing machine is designed primarily for
a one pass operation. If all operations prior to the
pass of the machine are as they should be, it rarely
will be necessary to make more than one finishing
pass with the machine.
15.3.2 Continuous OperationIf the forward speed is adjusted properly, the
machine will move forward at a uniform rate
eliminating frequent stops which cause variations in
the surface. It is true with this machine as it is with
other types of finishing equipment that continuous
operation, without stopping, provides smoother
pavement.
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STATE OF OHIO DEPARTMENT OF TRANSPORTATION
15.4 Cleanliness
The machine must be kept clean. The bottoms of the
screeds and the pan must be absolutely smooth.
Accumulations of hardened concrete (or oil and
grease) which might drop on the pavement must be
cleaned off continually. The machine should be
cleaned thoroughly every day.
33
Chapter 15.0: Operation of Combination Float Finisher
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
16.0 Slip Form Paving
16.1 General
This method of construction permits the placement of
pavement without the use of fixed side forms. In lieu
of forms, the paver vibrates, tamps, compresses and
strikes off the concrete while within the confines of
moving forms of the machine and extrudes the
consolidated concrete slab. Consolidation is such that
the vertical side faces of the slab retain their shape
and position after the passing of the traveling side
forms. Trailing side forms are needed only to protect
the slab edges during hand straightedging operations.
The specifications allow the Contractor the
option of using the slip form or the fixed form method
of pavement construction.
16.2 Subbase
Subbase must be constructed as outlined in the
specifications and in section 7 of this manual.
Stability of the subbase is considered to be critical for
slip form construction. If stability is lacking, the
subbase must be stabilized by added admixes or
angular aggregate particles at the Contractor’s
expense.
The subbase is to be graded to the plan elevation
by a properly designed machine. The track area may
be brought to grade using a form grader, with a
subgrader on crawlers used to grade the area under
the pavement. An automatic subgrader operating
from a preset grade line is considered ideal for slip
form con-struction and does not require the use of a
form grader.
Stabilization in the paver track area to provide
for traction is permissible, provided the area is
scarified after pavement construction to avoid
interference with lateral drainage of the subbase.
Any method of stabilization proposed by the
Contractor should be reported to the Construction
Section for consideration and approval.
16.3 Placing Concrete
An approved slipform paver or combination of pavers
shall be used to spread, consolidate, screed and finish
the concrete in one complete pass of the machine.
The machine shall consolidate the full width and
depth of pavement being placed so as to provide a
dense homogeneous pavement requiring a minimum
of hand finishing. Two machines may be used with
the front one striking off the bottom course for
placement of the mesh. The width of the bottom
course may be 150 mm (6 inches) narrower than plan
width so as not to interfere with the second paver.
The concrete shall have a slump of not more
than 75 mm (3 inches). If the slump exceeds 75 mm
(3 inches), the edges may be subject to settlement
after the forms have passed. Slump less than about 40
mm (1 1/2 inches) may result in an open textured
surface requiring excessive hand finishing.
Therefore, the slump should be maintained between
40 and 75 mm (1 1/2 and 3 inches) for best results.
Good construction results if the paver is
operated with a continuous forward motion with a
minimum of starting and stopping. When the paver
stops, all vibrating tamping and oscillating elements
must stop also.
34
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
At construction joints at the end of the day’s
production, the pavement may be reduced
approximately 50 mm (2 inches) in overall width.
This allows the Contractor to use an insert just inside
each moving side form to permit the paver to be
positioned at the joint when production is resumed.
The trailing side forms do not bind and spall the slab
edges when the leeway is provided on each side.
The slip form machine is not to be used as a
dozer to push large quantities of concrete piles out in
front. Therefore, some means of depositing and
striking off the concrete must be employed to permit
smooth uninterrupted operation of the paver. The use
of spreader boxes, a concrete spreader or any
technique that will provide a uniform distribution of
concrete is permissible.
16.4 Grade Control
Preset grade lines are required for slipform paving
equipment to assure acceptable riding quality of the
pavement. Preset grade lines may consist of: (1) a
stringline offset from and parallel with the edge of the
pavement; or (2) the compacted and trimmed surface
of the subbase.
If stringlines are used, they may be set on one or
both sides of the pavement and the grade transferred
to the paver through sensors following the grade of
the stringline. A smoother pavement is normally
obtained if two stringlines are used, one for each
pavement edge.
The grade may be traced from the surface of the
subbase by use of skis which electronically control
the grade of the slipform paver. When this method is
employed on one or both side of the pavement, the
subbase should be thoroughly compacted and the
surface grade closely controlled. Skis should be
placed in areas where the subbase is not affected by
any of the paving equipment.
The use of stringlines and subbase surfaces
alone will not assure riding quality. All lines, grades
and controls should be frequently observed to avoid
obvious errors. The electronic controls of the
slipform paving equipment are not capable of sensing
errors in the gradeline and, therefore, will duplicate
errors in grade controls in the pavement surface. In
order to attain the riding quality possible with
slipform pavers, constant attention must be given the
preset grade lines. When a stringline is used, the
stringline should be supported at intervals which will
eliminate sagging of the string under its own weight.
It has been found that supports every 8 m (25 feet)
produce the most desirable results. In addition to the
intervals between supports, the tension in the
stringline must also be taut enough that excessive sag
does not occur.
When slip form paving, inspection should
include checking the pavement edge. Since no forms
are used to screed against or to hold the edge in place,
the edge can slump downward or tilt out. This can
result in an area of lower elevation which will hold
water if pavement is placed against it. The edge of
the pavement shall not vary more than 6 mm (1/4
inch) below the typical section if pavement is to be
placed next to it. A straightedge can be placed
perpendicular to the edge to check transversely. In
addition, the straightedge can be placed longitudinally
at the pavement edge to check in that direction. Areas
which do not meet the tolerance must be corrected
while the concrete is plastic. The outside edge of
pavement, the edge that will not have concrete adjacent to
it, shall not vary more than 13 mm (1/2 inch) from the
typical section.
16.5 Finishing
Diagonal pipe floats suspended from self-propelled
machines have been used successfully to machine
finish slip form pavement without damage to the
unformed edges. They are equipped with a water
35
Chapter 16.0: Slip Form Paving
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
spray system which applies a fog spray of water.
Such water should always be a fog spray and should
be used only at the start of a finishing pass. With pipe
floats it may not be necessary to hand straightedge the
entire pavement surface. However, a straightedge
should be used periodically to check the pavement
surface.
Edging is accomplished by an attachment to the
machine or the trailing forms. With proper
adjustment, such devices can satisfactorily apply the
specified edge radius automatically.
Some machines trail several sections of forms
while others have no trailing forms. When trailing
forms are employed, they provide protection to the
edges while the surface is straightedged. However,
straightedging should not be confined to the area of
the trailing forms.
Equipment applying the texture and the
membrane curing compound straddle the pavement
the same as the paver and the pipe float. This
equipment rides on the subbase or subgrade.
Membrane machines are capable of covering the
vertical faces, as well as the horizontal surface of the
pavement, in one operation.
36
Manual of Rigid Pavement Practices
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
17.0 Field Checking
17.1 Running Yield
Running yields may be determined at any time during
a pour and provide an easy, accurate method of
checking. To make this, check the amount of
concrete required for one linear meter (foot) of
finished pavement of the width and depth being
placed is computed first. This normally is computed
by the followed formula:
or
In the case of a 7.2 meter wide slab, 255 mm
thick the following calculation would result:
or
In the case of the 24-foot wide slab, 9 inches
thick, the following calculation results:
Once this running yield factor has been
calculated, it can be used to determine the concrete
requirement for any length of slab of the same
dimensions simply by multiplying the slab length by
the factor.
The actual quantity used is easily computed for
any length of slab by multiplying the number of
batches placed by the number of cubic meters (cubic
yards) per batch.
Assume that 1,293 meters of the above metric
example pavement was placed and 345, 7-cubic meter
batches were placed. The running yield calculations
would be as follows:
1,293 m x 1.84 m³/m = 2,379 m³
345 batches x 7 m³/batch = 2,415 m³
2,415 m³ - 2,379 m³ = 36 m³ difference
36 m³ ÷ 2,379 m³ x 100% = 1.51 percent overrun
Assume 4,245 linear feet of the above pavement
was placed and 360, 8-cubic yard batches were used.
Calculations would be as follows:
4,245 linear feet x 2/3 yd ³ per linear ft = 2,830 yd ³
360 batches x 8 yd ³ = 2,880 yd ³
2,880 yd ³ - 2,830 yd ³ = 50 yd ³ difference
50 yd ³ ÷ 2,830 yd ³ x 100= 1.77% overrun
Generally due to wasting over the forms, spillage,
etc., the quantity used will be from 1 to 3 percent
greater than that required. Whenever this relationship
does not occur, immediate steps should be taken to find
the cause.
Overruns may be caused by several factors,
including inaccurate weighing, low subbase, excessive
waste, etc. Similarly, an underrun in concrete may be
37
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
due to inaccurate weighing, high subbase, loss of
crown, insufficient width of slab, settlement of forms,
etc.
17.2 Pavement Thickness
In order to insure that the specified thickness of
pavement is being constructed, the depth should be
checked periodically. This test is made as follows:
Place metal plates, approximately 125 to 150
mm (5 to 6 inches) square, on the subgrade. These
should be in line and spaced at about 1.2 meters (4-
foot) intervals between the forms or area of pavement
being placed. Sufficient references must be made so
that the plates may be located after the concrete is
placed. After the concrete at plate locations is in
place and the final mechanical equipment passes over
it, a small rod, such as a staking pin, is worked down
through the concrete at plate locations until it touches
the metal plate. The surface of the concrete is marked
on the rod and the rod withdrawn and the depth
measured.
Whenever the pavement is found to be deficient
in thickness all operations and equipment
immediately should be checked and corrected where
necessary, so that the proper slab thickness will be
obtained.
17.3 Crown
Where pavement is placed in single lanes, the
pavement slopes from the low edge to the high edge at
0.016 cross slope and can be readily checked for
transverse smoothness with a string or straightedge. In
this case, checks frequently should be made to insure
that the final pavement surface is as required.
If, however, the Contractor elects to finish the
two lanes of pavement with a crown in the center in
one operation, as when placing 7.2 m (24-foot)
pavement, the center 1.8 m (6 feet) of pavement is
rounded.
If slip form paving is used, the rounding is
optional.
Obviously when the pavement is so constructed,
a straightedge cannot be used to check the final
crown. The crown can, however, be readily checked
using two 76 mm (3-inch) steel blocks and piano wire
as follows:
1. Calculate at 0.6 meter (2-foot) intervals, the
height the pavement surface should be above a
straight line connecting the tops of the forms. For
example in a 7.2 meter (24-foot) pavement with the
high point in the center of the slab these heights are:
Distance from Center Height above Straight Line
meters (feet) millimeters (inches)
3.6 (12) 0 (0)
3.0 (10) 10 (3/8)
2.4 (8) 19 (3/4)
1.8 (6) 29 (1 1/8)
1.2 (4) 38 (1 1/2)
0.6 (2) 48 (1 7/8)
0 (0) 58 (2 1/4)
2. Subtract the values determined in (1) to
establish the distance the pavement surface should be
below a line 76 mm (3 inches) above and parallel to
the line connecting the tops of the forms. In the
example given above these values will be:
Distance from Center Distance below 3-inch Line
meters (feet) millimeters (inches)
3.6 (12) 76 (3)
3.0 (10) 66 (2 5/8)
2.4 (8) 57 (2 1/4)
1.8 (6) 47 (1 7/8)
1.2 (4) 38 (1 1/2)
0.6 (2) 28 (1 1/8)
0 (0) 18 (3/4)
3. Set the blocks on the cleaned forms and stretch
the wire across the slab. Then measure the distance
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Manual of Rigid Pavement Practices
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
the surface of the slab is below the wire. The
measured distance should closely match those
calculated in (2).
A crown check always should be made at the
start of paving operations to determine that all
equipment is properly set and functioning as it should.
Whenever deviations in crown from that specified are
found, immediate steps should be taken to correct the
situation. Checking crown and adjusting equipment
and operations should continue until the proper crown
is obtained.
It is advisable to make a daily check of crown
throughout construction to determine that changes in
equipment or procedure, which might effect the
crown, have not occurred.
17.4 Recording Checks
The fact that field checks were made should be
recorded on the Inspector’s Daily Report Form C-119.
Any checks found not in compliance shall be cause
for immediate corrective action and should be
followed with rechecks.
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Chapter 17.0: Field Checking
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
18.0 Final Finishing
18.1 Importance
Perhaps final finishing is the most important step inthe paving operation, at least from the publicviewpoint, because it determines whether or not thefinal surface meets the tolerance necessary for asmooth riding surface.
Projects using high-strength, quality concreteand the best of modern paving equipment often endup with substandard surfaces, simply because ofcareless work and lack of attention to details duringfinal finishing.
If forms are set accurately, and if all finishingmachines are adjusted and operated properly, thework of the hand finishers will be simplified, but itstill must not be neglected. If finishing machines donot function properly, additional work is required forthe hand finishers to correct surface irregularities andproduce an acceptable surface which complies withthe specifications. The preferred method is to keepthe machines in proper adjustment. In any case, it isup to the Inspector to insist that the finishers doproduce a pavement with the required smoothness andan acceptable uniform final surface texture.
The Inspector should see that the finisherschecks their hand tools before paving operationsbegin to make sure that they comply withspecifications.
18.2 Straight Edging
Straightedges should be tested with a string or a masterstraightedge to make sure they are straight. Thisshould be done daily and tools trued to correct for
wear. They must be rigid enough to remain straight
with no bending while in use. Handles must be 1
meter (3 feet) longer than one half the width of the
pavement. The straightedge itself shall be 3.0 meters
(10 feet) long.
18.2.1 Correcting Minor IrregularitiesAfter the mechanical finishing, while the
concrete is still plastic, minor irregularities and marks
in the surface should be removed with a scraping
straightedge. When necessary, excess water and
laitance should be removed from the surface
transversely by means of a scraping straightedge.
Any such excess should be wasted over the forms.
18.2.2 Type of ToolsA number of different types of straightedges have
been used satisfactorily. They must be strong enough
to maintain a true straightedge and yet light enough to
handle. In some cases they also must be heavy enough
to cut or scrape off any high spots left by the machine
finishing operations. They should be 3.0 meters (10
feet) long to comply with the specifications.
18.2.3 OperationThe straightedge is operated from the side of the
pavement transversely and should be advanced along
the pavement in successive stages. By proper
manipulation it can be used as a float to smooth the
surface or as a cutter to remove high spots.
18.2.4 Use of FloatsLong-handled floats may be used to smooth and
fill in open textured areas in the surface, but this must
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STATE OF OHIO DEPARTMENT OF TRANSPORTATION
be done before straightedge finishing. The use
of such floats should be held to a minimum. If open
textured areas persist, it is well to check the aggregate
grading, mix design and the method of placing the
concrete, for a properly proportioned mix should not
require hand floating if the preceding mechanical
equipment is properly adjusted.
No water is to be added to the surface during
this or any other operation.
18.2.5 Longitudinal JointsLongitudinal joints between separately placed
lanes require extra care to assure that a smooth
transition from one lane to the other will result. Good
workmanship is necessary at these joints to obtain
satisfactory results.
Edging on both sides of these joints should be
accomplished using a 3 mm (1/8-inch) radius tool.
Hand finishing and straightedging should be
performed carefully so that each lane will be at the
same elevation.
As a guide the surface of the pavement in the
joint area should not vary more that 3 mm (1/8 inch)
from a 3.0 meter (10-foot) straightedge in both
longitudinal and transverse directions.
18.3 Edging
Edging tools must be inspected to see that they have
the edge radius required. A 13 mm (1/2 inch) radius
is required for the outside edge of the pavement.
Longitudinal joints between separately placed lanes
require an edger with a 3 mm (1/8-inch) radius.
The slab should be edged as soon as the concrete
becomes stiff enough to remain firm without running
back into the groove. The edge first should be cut
with a small trowel and then followed by the edger.
The edging tool should be held flat with the pavement
surface. A trowel should be used to remove the bead
left by the edging tool. Since the final texturing is to
follow edging, this operation must not be permitted to lag.
18.4 Texturing
18.4.1 WhenWhen most of the water sheen has disappeared,
but before concrete becomes nonplastic, the final
surface texture should be applied.
Surface textures for concrete vary with the type
of construction. Finishing methods used must
produce the texture as described in the appropriate
specification item.
18.4.2 How to TextureUnless otherwise specified in the plans, exposed
concrete pavement (451 and 452) are to be textured
by the use of an artificial turf drag or broom drag in
the longitudinal direction immediately followed by an
approved device which will produce a uniform pattern
of grooves in the transverse direction. The turf or
broom drag must produce a uniform, gritty
longitudinal texture. The grooves shall be spaced at
approximately 16 mm (5/8-inch) centers and be
approximately 4 mm (0.15 inches) deep and 3 mm
(0.10 inches) wide. Concrete base pavement (305)
shall have a final surface finish that is a uniform gritty
texture as obtained with a broom or artificial turf drag
in the longitudinal direction.
Artificial turf drag, when used, should have
about 1 meter (3 feet) or more turf in contact with the
surface of the concrete. Such drags give best results
when a weight, such as reinforcing steel, is placed on
top of the turf and its entire width.
Brooms suspended from a machine or truss and
dragged over the pavement surface have provided
satisfactory longitudinal texture. The use of wire tines
for the transverse texture can impart the desired groove
depth and are less likely to build up with mortar.
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Chapter 18.0: Final Finishing
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
The reason for the use of broom or artificial turf
drag in the longitudinal direction is to provide a more
skid resistant pavement. The Department has found
that new concrete pavement would lose skid
resistance after one year of service with merely a light
burlap drag prior to tine grooving. Broom or turf drag
will roughen the area of concrete between grooves
which results in a longer lasting skid resistance.
Regardless of the method of texturing, the drag
or broom should be lifted clear of the surface when
not being used.
The surface at the pavement edges should be
dragged in the longitudinal direction when necessary
to remove any tool marks left during edging
operations. Tool marks or other surface blemishes
should not be present on the surface. The surface
should have a uniform texture.
18.5 Station Numbers
The Contractor is required by specifications to stencil
station numbers into exposed concrete pavement each
50 meters (100 feet). The dies used to form the
numbers must be 75 to 100 mm (3 to 4 inches) high
and 6 mm (1/4 inch) in depth. The numbers shall be
placed parallel to the pavement edge and centered 12
inches from and facing right edge of the pavement in
the direction of travel. The numbers should be
impressed following the texturing of the surface and
before curing is applied. If the impression is made too
early, the number will tend to close up and will not,
therefore, be as distinct as desired. The following
information applies to stenciling numbers in a dual
lane divided highway pavement project.
The right edge of a pavement is that edge to the
observer’s right as he stands on the pavement at the
low station and faces toward the high station. The
station numbers in the right pavement of a dual
pavement project then are so impressed in the
pavement that they may be read from a car traveling
on the paved shoulder from the low station towards
the high station or in the normal direction of traffic.
Station numbers also must be stenciled in the
left pavement. However, if the same pattern of
marking stations is followed on the left pavement of a
dual lane divided highway pavement project, the
numbers would be on the pavement edge next to the
median. Therefore, for the purpose of stenciling
station numbers in the left pavement of a dual lane
divided highway pavement project, the right edge of
the pavement shall be considered to be the edge on
the right of an observer as he looks from the high
station on the project towards the low station. The
station numbers then may be read easily from a car
traveling on the paved shoulder in the same direction
as the regular traffic.
Stations from 0 to 9 should include “+000”
(“ + 00”) after the digit. From station 10 on, the
“+000” (“ + 00”) is not necessary.
If concrete shoulders are placed with a traveled
lane, the station numbers should be placed 0.3 m (12
inches) in from the outside edge of the shoulder and
facing the pavement.
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Manual of Rigid Pavement Practices
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
19.0 Curing
Curing is the treatment or protection given concrete
during the hardening period.
Proper curing consists of keeping the concrete
moist and warm to insure adequate hydration of the
cement and to protect concrete from early shrinkage
due to changes in temperature and/or loss of moisture
before it has developed sufficient strength to resist the
resulting tensile stresses.
19.1 Value of Adequate Cure
It is extremely important to provide adequate curing
during the first few days, with the first few hours
being most important to obtain a strong durable
surface. Strength loss due to lack of moisture during
this
period is difficult to regain even with subsequent
curing.
Any one of the several methods of curing
permitted will give satisfactory results if correctly
accomplished. One method may be used throughout
the entire curing period, or it may be considered
better to use a combination of two methods, initial
and final.
Curing should begin as soon as the texturing
process is completed, providing that the finished
surface does not have free water on the surface.
19.2 Effect of Variable Weather
During windy, hot, dry weather it is very important that
the finishing be completed rapidly and the curing be
placed before the surface dries out to the extent that
plastic shrinkage cracks develop. These cracks never
can be sealed, and they also are an indication that the
surface may have been depleted of the necessary
water to properly complete the chemical reaction of
hydration.
Water curing may halt this shrinkage cracking,
but even the addition of more water will not correct
the cracking once it occurs.
In cold weather, the concrete may continue to
bleed after finishing. Care should be taken in placing
any type of curing under these conditions so that the
surface will not be marked. The minimum period for
curing is 7 days, unless specimen beams have attained
a beam strength of 4.2 MPa (600 psi). During cold
weather, concreting the pavement shall be protected
from freezing temperatures until beams attain a
strength of 4.2 MPa (600 psi).
Prior to application, the curing material should
be inspected to assure that it meets specification
requirements. This also applies to any equipment used
in the application.
19.3 Types Permitted
Liquid membrane curing compound is the most
popular method of curing. However, water curing,
waterproof paper, and polyethylene sheeting
are acceptable methods for curing pavement
concrete.
19.4 Membrane Curing
19.4.1 General CommentMembrane materials shall meet specification
requirements and be applied at the minimum rate of 1
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STATE OF OHIO DEPARTMENT OF TRANSPORTATION
liter per 3.7 square meters (one gallon per 150
square feet) for Items 451, 452 and 453. Concrete
base, Item 305, shall be treated at the minimum rate
of 1 liter per 4.9 square meters (one gallon per 200
square feet). Exposed concrete with a grooved (tined)
surface requires more curing compound than base
concrete due to the additional surface area caused by
the grooves as opposed to only turf drag or broom
drag finish on the base pavement.
If properly applied, these membrane compounds
prevent evaporation and the retained water provides
excellent curing. Therefore, the principal caution that
should be exercised is to make sure that the specified
rate of application is adhered to and the curing
compound is applied evenly so that a uniform
thickness of membrane coating is obtained. If this is
not done, the quality of concrete will be affected.
White pigmented compound is the only
membrane acceptable on paving projects. This has an
advantage over clear type compounds in summer
construction in that it provides a coating that reflects
heat from the surface and thus decreases heat
absorption in the pavement and the tendency for
transverse cracks to develop in forenoon pours. In
addition, its white color permits visual inspection for
uniform coverage.
19.4.2 How to ApplyOn uniform width slabs application of the curing
compound is made by a power driven mechanical
sprayer which rides the forms or straddles the
pavement if the slipform method is used. Hand
operated sprays are used on sections of variable width
and on the pavement edges after form removal.
The white pigment used in the membrane acts as
an abrasive which tends to enlarge the apertures of the
spray nozzles and to reduce the efficiency of pumping
equipment. Equipment used to apply membrane should
be cleaned frequently and checked to see that it is
providing a uniform protective covering.
19.4.3 Care and StorageCuring compounds especially pigmented ones, tend to
separate during storage. It is important that the material be
stirred thoroughly prior to application in order to obtain a
uniform product and to avoid wastage by leaving heavier
fractions of the compound in the drums. Drums are equipped
with internal paddles for stirring the material to mix the
pigmented compound. A crank is attached externally to a
shaft on one end of the drum to engage the paddles. Drums of
curing compound stored for any length of time should be
placed in storage upside-down so that when they
are reversed prior to use more thorough mixing will
result.
19.4.4 TimingAccurate timing of application is most
important. Membrane never should be sprayed on a
surface until all free water has evaporated and the
concrete has lost its sheen. If membrane is placed on
free water, it tends to float with the result that when
the water disappears the membrane will craze or crack
and peel from the surface. Whenever the texture of
the surface is marred by the application, the concrete
either is too wet to too green, and the application
should be delayed until the membrane may be applied
without disturbing the textured finish.
Any membrane disturbed by foot traffic or by
any other cause should be corrected immediately by
making a second application of the curing compound
with a hand sprayer.
At the close of paving each day, a check should
be made of the number of drums of membrane curing
compound used. This quantity should be checked
against the square meters (square feet) of pavement
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Manual of Rigid Pavement Practices
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
placed to assure that minimum application is
achieved. This check shall be recorded on the
Inspector’s Daily Report, Form C-119 and filed in the
project records.
19.5 Curing with Paper orPolyethylene Sheeting
This method employs the use of waterproof paper or
polyethylene meeting specification requirements
(705.05 and 705.06). These materials are to be placed
on the concrete as soon as possible after finishing
without marring the surface and are to be left in place
for the full curing period.
19.5.1 Inspection of SheetThe advantage of this curing method is that no
sprinkling or other attention is necessary after
placing, except to make sure that it is anchored
against blowing off by wind and that holes or torn
areas do not occur. The blankets should be inspected
daily during use. Before being reused, small holes or
breaks should be repaired in satisfactory manner.
19.5.2 Proper PlacementThe blankets should be placed so as to cover full
width of lane and lapped at least 0.3 m (12 inches).
When forms are removed, edges should be completely
covered. This may be done by turning down the edge
of the blankets or narrow strips pulled out from under
them. These narrow strips are placed on the concrete
before main sheets are laid.
19.5.3 PrecautionsThese blankets never should be dragged over
fresh concrete and should be placed so as not to mar
surface.
One of the principal precautions in this method
of curing is to make sure edges along forms are sealed
so that there is no possibility of air getting under the
curing material. This is important for two reasons: (1)
unless the seal is adequate, air can circulate over the
pavement which will dry out the surface and result in
inadequate curing; and (2) heavy winds will get under
the blankets and rip them off leaving the pavement
without any curing at all.
19.6 Water Curing
19.6.1 TypesVarious methods of water curing are permitted
by the specifications. These methods include burlap
cloth, waterproof paper or polyethylene sheeting.
These methods are used very infrequently and
therefore are not discussed in detail.
19.6.2 Moisture ControlIf the Contractor should elect to use one of the
water curing methods, his operation should be checked
closely to assure that the curing is done in accordance
with specifications requirements. Make sure that the
pavement is wet at all times. This type of curing
requires constant checking throughout the curing
period.
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Chapter 19.0: Curing
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
20.0 Work to be Done Later
20.1 Form Removal
The presence of forms during the early curing protects
the pavement edges against damage and also serves
as a curing method for the pavement edges.
20.1.1 When to Remove FormsDuring warm weather, the common procedure is
to remove the forms approximately 24 hours after the
concrete is placed. During cold weather, it may be
advisable to leave forms in place for a longer period.
In any event, forms should not be removed until the
concrete has attained sufficient strength to prevent
damage to the concrete surface or breaking of the
edges during removal.
20.1.2 How to Remove FormsThe method used to remove the forms should be
such that the concrete pavement will not be damaged.
In addition, the Contractor should be encouraged to
use a method which will not bend or otherwise
damage the forms.
Pin keys first should be loosened, form joint
locks unfastened and nuts removed from end of hook
bolts (single lane paving). Pins then should be
removed from their sockets using a direct vertical lift
without any pressure toward the concrete. The
necessary action to exert the vertical lift should be
from the forms or the ground outside forms. If any
equipment is used to pull pins which may ride on the
concrete, care should be taken to assure that no
pressure is on the concrete other than the weight of
the equipment.
After pins are removed and other preliminary
work finished, light blows with a hammer or careful
prying on base flange may be used to separate forms
from concrete. Prying against the edges of concrete
with bars to break forms loose never should be
permitted.
20.1.3 Care NecessaryThe method used to move forms away from
concrete should be such that each form section will be
pulled horizontally away from edge before it is lifted.
Particular care with regards to this action is necessary
when forms with keyways are used.
20.2 Edge Patching
20.2.1 Inspection of EdgesWhen forms have been removed, edges should
be checked immediately and honeycomb areas
filled.
20.2.2 Repairing HoneycombMortar should be used to fill all honeycomb
areas. Inspections should be made of filled areas to
make sure the entire areas are tightly packed and
struck off flush with surface of the pavement
edge.
20.2.3 Cleaning at JointsJoints should be checked to make sure the ends
are cut through the edges and no concrete is left in the
grooves or around joint materials. Sawed joints should
46
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
be cut through the pavement edge so that vertical
cracking is assured and preformed compression seals
can be installed easily.
20.2.4 CuringCuring should be applied to edges just as soon as
forms have been removed and patching and cleaning of
joint ends has been completed. This will assure
satisfactory curing as well as preventing the loss of
water necessary for hydration of the cement.
20.3 Joint Sealing
20.3.1 GeneralTransverse and longitudinal joints are sealed to
prevent infiltration of incompressible material. Sealing
also limits entrance of surface water to the subbase.
Pavements contract or shrink when temperatures
drop, thereby causing joints to open. When
temperatures rise, pavements expand and joints close.
The presence of incompressible material prevents the
joint from closing during expansion and subjects the
concrete to compressive stresses. Proper sealing
prevents intrusion and permits joints to perform as
intended during movement of the pavement slab.
20.3.2 When to SealSealing should be done as soon as is feasible
after joints are sawed. All joints must be sealed before
the pavement is opened to traffic. Approval may be
granted upon request to place temporary material to
protect the joint opening during use by construction
traffic.
20.3.3 Cleaning JointsPrior to filling, all joints must be cleaned.
Cleaning consists of operating a saw blade backward
through the saw groove to remove all pebbles, trash,
dirt, etc. Any other operation which satisfactorily
cleans the groove is permissible. The final step in
cleaning shall consist of blowing out the joint opening
using compressed air or by a jet of clean water.
20.3.4 Expansion JointsExpansion joints must be clean for the full width
of the expansion material, and the top of the
expansion material must show over its entire area.
The presence of any concrete around the expansion
material will prevent free compression of the joint
material and may cause spalling along the joint when
the pavement expands.
20.3.5 Joint SealersPreformed compression joint seals are required
in transverse contraction and construction joints in
451 pavements and most 452 pavements. Seals should
be checked to assure they meet specification
requirements (705.11) and are the width specified in
the standard drawing. Installing equipment should be
inspected to make sure it is in good working condition
and is capable of installing the size of sealer
specified. Contraction joints in concrete base are
sealed with a hot applied material meeting the
requirements of 705.04.
Hot applied joint sealer (705.04) or performed
compression joint seals (705.11) may be used for
sealing longitudinal joints in plain or reinforced
pavement if joints are sawed or hand formed. Since
the hot applied sealer requires heating, frequent
checks should be made to avoid overheating to a
temperature higher than the manufacturer’s
recommendation. Check samples shall be taken daily
but should not be taken after a long period of heating.
These samples are sent to the Laboratory.
Longitudinal joints in Item 305, concrete base do not
require sealing.
20.3.6 Condition of JointJoint walls must be inspected just ahead of filling
to make sure that they are dry and thoroughly clean. It
is essential that the walls be in this condition if the
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Chapter 20.0: Work to be Done Later
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
sealer is to function properly. If the sealer fails to
adhere to the concrete, water and foreign material will
filter into the joint.
20.3.7 Sealing OperationWhen using liquid sealing compounds, pouring
should be done in such a manner that complete filling
from the bottom of the joint slot to approximately
level with the surface of the pavement is assured. It is
a waste of material and poor workmanship to use a
filling method which leaves a smear of sealing
compound on each side of the joint opening. With
some compounds it may be necessary to fill the joint
in several applications. Workers should not allow the
sealing compound to spatter or drip onto the adjacent
pavement.
If the joint is filled too fast the sealing material
will run to the low side. When using hot poured
compounds they may flow out of the joint at the edge
of the pavement if some method of plugging the edge
is not used. A satisfactory plug can be provided by
any one of the following methods:
1. A ball of mud pressed over the end of the
joint.
2. A small piece of roving jute pressed vertically
into the joint end, flush with face of pavement
edge.
3. A small piece of masking tape placed over
the end of joint.
The surface of the hot applied sealing material will
rise as the temperature increases causing the pavement
to lengthen and the joint to close. Conversely, the
surface will fall as the temperature decreases,
contracting the slab and causing the joint to open.
Filling then should be such that the surface of the hot
applied sealing material will be approximately level
with the pavement surface when the pavement
temperature is about 21C (70F).
Never over fill a joint to the extent that a bump
will be produced at the joint. Such a practice is a
waste of material, creates an unsightly condition, and
affects the riding quality of the finished pavement.
The bumps created by the excessive material will be
readily noticeable to the traveling public from a
smoothness standpoint, as vehicles pass over each
joint.
When placing preformed compression seals in
contraction and construction joint seals should be
installed by machine or by hand methods in such a
manner to avoid stretching the seal excessively. A
maximum elongation of 5 percent should be enforced
during installation. If hand methods are used, seals
that are nicked or cut should be removed and
replaced. An approved lubricant adhesive should be
used to aid in placing the compressed seals into the
joint opening. The seals should be placed so that they
are approximately 6 mm (1/4 inch) below the level of
the pavement surface.
20.3.8 Removal and Repair of UnsatisfactoryPoured Sealer
Prior to final acceptance of the pavement any
unsatisfactory seal should be removed and replaced.
All low spots in sealing compounds must be brought
to the desired level, and any high spots should be cut
off and the excess material removed.
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Manual of Rigid Pavement Practices
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21.0 Hot Weather Construction
21.1 General
Specifications do not cover precautions necessary for
placing concrete during hot weather. However, when
high air temperatures, low humidity and winds are
encountered during concreting operations adjustments
must be made in order to assure quality. Any one of
these factors or combination of them speeds up the
rate at which concrete hardens. High temperatures,
especially when accompanied by wind and low
humidity tend to cause a rapid loss of moisture from
the surface of the pavement resulting in early setting
and a reduction in time allowed for finishing.
21.2 Adjustments
In order to counteract the adverse effects of hot
weather, it is necessary to control the temperature of
the concrete mix. Lowering the concrete temperature
to 24C (75F) or below will offset the effects of hot
weather. Selection of a cool water supply is the most
effective means of lowering the mix temperature.
Sprinkling of coarse aggregate stockpiles for moisture
control also aids in controlling the mix temperature.
21.3 Slump
It is a good practice when form paving to maintain the
slump of the concrete near the top limit during hot
weather. Increasing the slump delays the stiffening,
thereby making more time available for the finishing
operations. It is good practice to have any additional
water added at the job site thoroughly blended into
the mix to provide workability.
The use of water on the surface during finishing
results in an increase in the water-cement ratio and
washes out the entrained air in the concrete at the
surface. Needless to say, both of these changes
adversely affect the durability at the surface. The use
of the whitewash brush has probably been the cause
of the majority of scaling occurring in concrete
surfaces. Therefore, the use of water on the surface
during finishing shall not be tolerated.
21.4 Fog Spraying
Under extreme drying conditions mixing water may
evaporate quickly from the surface of the concrete.
This water may be restored by applying a fog spray of
water on the surface, provided the surface has been
completely finished and will not be screeded or
straightedged. This provision should be controlled
carefully and should be the exception rather than the
rule.
21.5 Admixtures
Use of an approved set retarding type admixture may
be desirable in hot weather to retard the setting time
thereby providing more time for finishing. Project
personnel must be aware that a water reducing
retarding admixtures (705.12, Type D) is required in
the concrete (for any concrete usage) if the concrete
temperature exceeds 24C (75F). The use of this
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STATE OF OHIO DEPARTMENT OF TRANSPORTATION
admixture will result in less slump loss and result in
high strength concrete. Admixtures for accelerating
the set will be permitted only when provided for in
the contract or upon the written permission of the
Director.
21.6 Rain
An ounce of prevention is worth a pound of cure. If
the pavement is protected, much time and expenditure
in corrective work can be avoided. A roll of
polyethylene sheeting on the finishing machine can be
quickly unrolled to protect large areas of pavement
and corrective measures can be avoided. When the
concrete has not been protected and has been
damaged by rain, increased attention to corrective
measures will be necessary to obtain durable concrete.
Concrete which has been exposed to rain will
have some mortar or paste washed from the surface.
The surface usually has a sandy appearance when the
cement paste is removed. In addition, it will have a
speckled or spattered appearance. Quality can be
restored to the surface by several methods.
If the surface has not been machine finished, it
should be screeded with the machine. This screeding
will eliminate the sandy texture and force grout to the
surface. For a surface which has been machine
finished, the machine may be used to make a single
pass over the area affected, or the surface may be
dragged with the burlap to remove the sand and work
grout to the surface. The burlap drag may have to be
used for several passes to restore the surface finish.
Pavement which has been damaged by heavy
rain should be reworked with the finishing machine, if
the concrete has not taken its initial set. If it has, the
burlap drag alone should be used repeatedly until the
surface has been corrected.
When correcting damage to newly placed
concrete surfaces, the excess surface water must be
removed. It definitely should not be worked into the
concrete. Cement should not be placed on the surface
in an attempt to restore cement paste washed away by
the rain. Such a practice is detrimental to the concrete
rather than helpful.
When a rain persists for a lengthy period of
time, it will be necessary to remove any protective
covering to finish and texture the concrete before it
stiffens and sets. After this has been accomplished the
concrete may be recovered. Membrane curing should
not be applied when the surface is wet and may be
delayed until paving is resumed. If a polyethylene
sheeting is used as a covering, curing may be delayed
indefinitely provided the sheeting is maintained in
accordance with the specifications. However,
membrane curing eventually should be applied to
provide a surface uniform in appearance.
If rain damages the curing membranes, the
surface should be resprayed after the excess water has
dissipated to restore the impervious covering and
retain moisture necessary for curing.
Concrete subjected to rain can be restored to its
original quality provided attention is given to the
details mentioned above. The usual difference
between a rain damaged pavement that is satisfactory
and one that is undesirable is that the finishing crew
did not quit but persevered until satisfactory results
were obtained.
If, for any reason, measures taken by the
Contractor to produce a surface that meets
specifications are unsuccessful, the affected portions
of the pavement must be repaired or replaced to
comply with contract requirements.
There is equipment available that can groove the
transverse texture into pavement that does not have
adequate texture. The equipment must meet the
requirements of 451.122 and be approved by the
Engineer.
Manual of Rigid Pavement Practices
50
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
22.0 Cold Weather Construction
22.1 General
During cold weather, provisions must be made to
prevent concrete from freezing until it has attained
adequate strength. Concrete which has been frozen
before gaining sufficient strength may be damaged
permanently and may never achieve the design
strength. Therefore, it is necessary to protect the
concrete from freezing temperatures during curing in
order to prevent damage and to obtain the design
strength.
The temperature of the concrete and the
surrounding air directly control the rate of hardening of
the concrete. When these temperatures decrease, the
rate of hardening decreases. The rate of hardening
ceases at the freezing point. If the concrete is
maintained just above freezing, it will not be damaged.
However, it will require a lengthy curing period before
it will harden and gain strength sufficient for removing
forms. Under these conditions it is necessary to provide
heat to the concrete so that it will harden and gain
desired strength within seven days.
The Contractor is responsible for protecting
concrete during cold weather. If damage might possibly
occur, the surface shall be protected by any means that
prevents the concrete from freezing and retains the heat
of hydration.
22.2 Adjustments
In order to control the rate of hardening and gaining
strength it may be necessary to control the temperature
of the concrete being placed and to protect the concrete
to retain the heat of hydration during curing. If the air
temperature is 2C (35F) or below when concrete is
being placed, the concrete shall be heated to a
temperature of from 10C to 27C (50 to 80F) when
placed.
Heating mixing water is the most effective way of
heating the concrete. Aggregate may be heated, if
necessary, in addition to the water. The heated water
and aggregate should be introduced into the mixer
before the cement, so that the temperature is reduced
before cement is added to avoid the possibility of a
flash set. One further precaution is to delay the
introduction of the air-entraining agent until the
temperature has been reduced, because hot water
tends to reduce its potency.
The subgrade or subbase and forms shall be free
from frost when concrete is placed. Covering these
areas usually will prevent frost and avoid delays.
22.3 Admixtures
Any request to incorporate an accelerating admixture
during cold weather construction shall be submitted
and approved as outlined in Sec. 21.5.
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STATE OF OHIO DEPARTMENT OF TRANSPORTATION
23.0 Job Control Testing and Sampling
23.1 Tests
Concrete for use in pavements must meet specified
requirements for air, slump and yield. Tests must be
conducted to check for compliance with these
requirements. The Inspector will conduct these tests
after the concrete has been delivered and deposited on
the subbase. The test results must be within the
following limits:
Air 6 ± 2 percent
Nominal Slump 25-75 mm (1 to 3 inches)
Maximum Slump 100 mm (4 inches)
Yield ± 1 percent
If tests indicate the concrete is not within these
limits, immediate adjustments must be made.
Production should be stopped and check tests made to
confirm noncompliance of the original tests. Concrete
that does not meet specification requirements shall
not be permitted to be used unless adjustments can be
made to correct the deficiency. The fact that concrete
has been produced and transported to the project does
not justify its use unless it conforms to requirements.
Insufficient air may be corrected by the addition
of an air-entraining agent and remixing to generate
additional air. Variations in yield should not be cause
for rejection; however, immediate adjustments must be
made in the batch weights and must be followed by
additional yield tests until conformance is obtained.
Slump may be increased by the addition of water
provided it remains within the above limits. If slump is
excessive the concrete should not be used.
23.2 Sampling
All material being used in the production of concrete
shall be sampled, tested and approved before being
used. Material that has not been sampled before
delivery to the project must be sampled and submitted
for testing. Such material must not be used until
approval has been given by the Laboratory. Sampling
shall be done in accordance with the specifications
and as outlined in Manual of Procedures for
Concrete.
23.3 Cylinders
Cylinders are not required for pavement concrete.
However, if for some reason cylinders are desired,
they should be cast from concrete obtained at the
paving site and are to be made in accordance with the
Manual of Procedures for Concrete. Cylinders are to
be shipped to the Laboratory on the fourth day after
casting where they are tested for compressive strength
at 28 days of age.
23.4 Beams
Beams are required for each 6500 m2 (7,500 square
yards), or fraction thereof, of pavement placed each
day. Instruction for making and testing beams are
found in the Manual of Procedures for Concrete.
Beams are tested at the project by the project
personnel.
The completed pavement may be opened to
traffic, including construction traffic, after 7 days have
52
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
elapsed. The pavement may be opened to traffic after
5 days provided a beam strength of 4.2 MPa ( 600
pounds per square inch) has been attained. If it has
been determined that it will be necessary to open a
portion of the pavement in fewer than 5 days, high
early strength concrete shall be used, and the
pavement may be opened to traffic after 3 days
provided the test beams attain a strength of 4.2 MPa
(600 pounds per square inch).
Beams normally are tested at 5 and 7 days. If
results are not needed before the end of 7 days, only
one beam break is necessary. This break should be
made at the age of 7 days.
The maximum capacity of the beam breaker is
6.7 MPa (1,000 pounds per square inch) and is
marked on the beam breaker dial. The capacity must
not be exceeded. Beams that do not break when loaded
to the capacity of the breaker should be recorded as
>6.7 MPa (>1000psi) or whatever the unbroken
strength was when the test was stopped, such as 5.9
MPa + (850psi +) for example.
A slump, air and yield test shall be made each
time beams are cast. Concrete for these tests shall be
obtained from the same batch of concrete as that used
in casting the beams.
23.5 Records
Results of air, slump and yield tests are to be
recorded on the Concrete Inspector’s Daily Report as
outlined in the Manual of Procedures for Concrete.
Results of compression tests on cylinders
submitted will be reported by the Laboratory in the
Construction Management System (CMS) under Test
Data Reports.
Results of flexural tests on beams are to be
recorded in the project records.
53
Chapter 23.0: Job Control Testing and Sampling
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
24.0 Pavement Cores
24.1 General
The Laboratory will remove cores from the completed
pavement to check the pavement thickness in
accordance with 451.16 of the specifications. A core
is taken at random for every 1,650 square meters
(2,000 square yards) of pavement. Locations for
random cores are determined by the Laboratory
whose personnel remove, measure and report
thickness measurements.
24.2 Cooperation
Project personnel are requested to cooperate by
providing assistance as needed to obtain the required
cores. Since the Laboratory technician is not
authorized to take extra cores, such requests
must be made through the District or to the
Laboratory.
24.3 Filling Holes
Specifications require the Contractor to fill all core
holes using the same concrete used in constructing the
pavement. Therefore, the Inspector shall check for
compliance with this requirement.
When filling the core hole, the surface should be
damp and should be painted with a grout consisting of
cement and water having the consistency of a thick
paint. Stiff concrete should then be rodded into the
core hole before the grout dries. The surface should
be struck off and curing membrane applied to provide
curing essential for a durable replacement.
24.4 Measurements
Cores are measured in the field by the Laboratory
technician so that additional cores required may be
obtained at the same time if a thin core is
encountered. Cores are transported to the Laboratory
where they are measured in accordance with
AASHTO T 148.
24.5 Records
If the measurements indicate a deficiency resulting in
a price adjustment, a teletype will be sent by the
Laboratory to the District. A copy of this teletype
should be forwarded to the Engineer and should be
considered when reporting pay quantities for progress
estimates.
After cores are measured they are tested in
compression. After these results are obtained, the
Laboratory will enter the thickness and compressive
strength into CMS. The information will then be
accessible by project personnel.
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STATE OF OHIO DEPARTMENT OF TRANSPORTATION
25.0 Surface Smoothness
25.1 General
The surface of the completed pavement shall be
cleaned and tested for smoothness by means of a
surface testing machine. Testing shall be done after
the final curing of the pavement. A profilometer is
used to detect and mark the surface variations which
are in excess of the allowable tolerances. For
pavements where the degree of curvature is less than
8 degrees or grades are less than 6 percent, the
tolerance is 3 mm in 3.0 m (1/8 inch in 10 feet). For
ramp pavements and for those pavements that exceed
the 8-degree curvature or 6-percent grade, the
tolerance is 6 mm in 3.0 m (1/4 inch in 10 feet).
Normally two lines, one in each wheel path, are
checked in each 3.6 meter (12-foot) lane.
Profilometers are assigned as outlined in
Directive DH-30C to serve all 12 districts.
25.2 Corrective Work
Surface variations indicated by paint applied by the
profilometer shall be ground off to within tolerance in
accordance with 451.121. This section requires the use
of diamond grinders. Bush hammering, carbide tipped
grinders or any method that may damage the bond of
the aggregate or shatter the aggregate shall not be
permitted. After diamond grinding, transverse
grooving with diamond grooving equipment must
leave the final surface in conformance with 451.09.
Equipment is available commercially to correct
surface variations and provide adequate texture. If
unfamiliar equipment is proposed for use, a check
should be made with the District office to ascertain if
the equipment is acceptable.
A 3.0 meter (10-foot) straightedge should be
used to check for compliance when corrective work is
in progress. The straightedge should be used also to
determine the transverse limits of the area to be
corrected. Usually variations extend beyond the wheel
path and may require diamond grinding and grooving
the entire width of the lane. Only by checking with a
straightedge can this determination be made.
Areas which are low should be corrected by
grinding on each side until within tolerance. If these
areas cannot be corrected by grinding, they shall be
repaired or replaced to the satisfaction of the Engineer.
25.3 Records
The Inspector assigned to this corrective work should
record the limiting stations of work satisfactorily
performed each day. This data should be recorded on
the Inspector’s Daily Report, Form C-119 and also
entered in the Daily Diary in CMS.
55
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
26.0 Measurement
The plan quantities as adjusted for changes, errors and
deviation in excess of allowable tolerances is the
method of measurement. The length of the roadway is
checked at one time or another during construction and
should serve as the length to be used in determining
pavement quantities. This measurement should be a
matter of record. The width of pavement is spot
checked daily during routine job control and assures
that the specified width is obtained. These length and
width measurements should be checked against those
used in the calculations to assure that plan quantity is
correct. Pavements such as ramps, intersections,
entrances and exits to interchanges which have
variable width shall be measured to determine if the
plan calculated area is correct. If the plan quantity is
in error, the quantity for payment must be calculated
using the actual dimensions measured.
Any changes in plan that involves concrete
pavement quantities must be shown on the form used
to document the final pay quantity. Also, any areas
found to be deficient in thickness must be indicated
on the form and adjustment made in the pay quantity.
56
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
27.0 Concrete Pavement Repairs
During the life of concrete pavement, it sometimes is
necessary to make repairs to arrest progressive
deterioration and to maintain serviceability. Timely
repairs will restore quality and provide the rideability
and life expectancy for which the pavement was
designed.
Problems may occur at various stages of the
pavement life and it is important that they be
corrected as the need arises. Often, corrections are
necessary during construction and these repairs must
be of the highest standard if the anticipated pavement
life is to be realized. This subject is covered here to
establish a standard procedure and to provide uniform
application for repairs made prior to completion of
the construction contract. These standards also will be
applicable at any time throughout the pavement life.
Generally, concrete pavement repairs are classed
as full-depth pavement replacement and thin-bonded
patching. Full-depth replacement will apply when the
damage is more extensive than surface scaling or
spalling and necessitates removal and replacement for
the full depth of the slab. Thin-bonded patching
applies to surface scaling and spalling, spalling at
edges and joints, and other surface deterioration that
does not extend below the pavement mesh. Thin-
bonded patching also is applicable for similar
deterioration on bridge decks and especially for
spalling associated with insufficient cover over the
top mat of reinforcing. Excellent results have been
obtained for correcting the last mentioned condition by
removing concrete from below the steel and forcing the
steel to a lower position before placing the patching
concrete.
Compliance with all the provisions of the
following standards is necessary to assure durable
repairs and to restore the quality of the facility
permanently.
27.1 Full Depth PavementReplacement
Full depth pavement repairs, when required prior to
acceptance of a new concrete pavement or when
required by a rehabilitation contract, are constructed
in accordance with Item 255, Full Depth Rigid
Pavement Removal and Rigid Replacement. When
this specification is called for, Standard Construction
Drawing BP-2.5M (BP-2.5) entitled Rigid
Replacement shall also apply to the work.
The basic process of full depth repair includes
the following:
1. Full depth diamond sawing
2. Pavement removal
3. Compaction of subbase
4. Drilling dowel bar holes
5. Grouting dowel bars and tiebars
6. Placing, finishing and curing concrete
7. Sealing of joints
27.1.1 Pavement SawingThe limits of the areas to be repaired are marked
by the Engineer. The minimum longitudinal length of
a repair is 1.8 meters (6 feet). All pavement repairs are
normally the full lane width unless otherwise detailed
by the plan.
57
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
The existing pavement is sawed full depth at the
limits established by the Engineer with a diamond a
saw blade. All diamond saw cuts are perpendicular to
the centerline of the pavement lane. Normally, the
existing concrete pavement thickness is given in the
plan. There may be older projects where the existing
pavement was built thicker than specified in the new
repair plan. Concrete sawing and removal depths may
be as much as 25 mm (1 inch) greater than indicated
on the repair plan without additional compensation to
the Contractor.
If there is an existing asphalt overlay on the
concrete pavement, the Contractor may elect to saw
full depth through the asphalt and the concrete.
Depending on the thickness of each material, the
Contractor may not be capable of sawing through
both courses and may elect to make an offset saw cut
through the asphalt course and remove enough asphalt
to allow a diamond saw to saw full depth through the
concrete pavement. If the Contractor elects to make
offset cuts to facilitate the removal, they will not be
measured for payment. Only full depth saw cuts that
are made at the limits of the removal are measured for
payment. Intermediate saw cuts made by the
Contractor to facilitate removal by the lift out method
will not be measured for payment.
During hot weather, it may be necessary for the
Contractor to saw only at night or morning when
cooler temperatures prevail. Concrete pavement heats
up and expands as temperatures rise during hot
summer days. Diamond saw blades can be pinched
and locked up during sawing by the pavement slabs
due to the pavement expansion.
27.1.2 Pavement RemovalRemoval of the concrete follows the full depth
sawing operation. In order to not disturb the base
under the pavement and to minimize the damage to
the adjacent pavement which is to remain, the lift out
method is required. Holes are drilled within the
removal area and lift pins are inserted. The slab or
portion of the slab is then removed by lifting the slab
vertically with a crane or backhoe. After lifting, loose
debris left behind is removed by hand methods. The
pavement removed is disposed of in accordance with
Item 202. Intermediate sawcuts within a longer slab
replacement are not measured for payment.
The use of a pavement breaker and backhoe for
removal is not permitted unless the Engineer
determines that the lift out method is not practical
because of extensively deteriorated pavement,
existence of bituminous full depth repairs or old
concrete pavement repairs which are extensively
cracked and deteriorated. There will be no additional
compensation for removal of the pavement by
pavement breaker and backhoe.
Regardless of the method used to remove the
pavement, if the pavement to remain is damaged by
the sawing or removal operations, an additional full
depth diamond saw cut is required full width of the
lane or lanes at a distance from the first cut that will
encompass the damaged pavement. The additional
pavement repair area and the additional saw cut is not
measured for payment.
After pavement is removed from the area to be
repaired, if the face of the remaining pavement is
deteriorated on the bottom to a height greater than 1/4
of the pavement thickness an additional saw cut shall
be made. The additional saw cut shall be made 305
mm (12 inches) back from the original saw cut. The
additional saw cut and repair area is measured for
payment.
27.1.3 Compaction of SubbasePrior to placing the concrete in the removal area
and before installing dowels or tiebars, any subbase or
subgrade that is disturbed below the level of clean out
is removed. The repair area shall be compacted to the
satisfaction of the Engineer. Any area which has been
over excavated is to be filled with concrete. On
undercut full depth repairs, the removal of subbase for
the undercut is incidental and included in the pay item.
Manual of Rigid Pavement Practices
58
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
If undercut joints are specified, the Contractor
must be careful when removing subbase under thepavement which is to remain. Damage to the bottomof the slab that is to remain should not be tolerated. Ifa backhoe bucket plate is used, care must be exercisedor hand methods must be used to undercut theexisting slab.
27.1.4 Drilling Dowel or Tiebar HolesDrilling of holes for dowels or tiebars is to be
done with hydraulic or electric drills in a manner thatwill not spall or damage the existing concrete. Thesetypes of drills do not impact the face of the saw cutwith as much force as a pneumatic drill. Holes are tobe drilled with a device that allows independentadjustment of all drill shafts in the horizontal andvertical direction. The device shall be capable ofdrilling a minimum of three holes at one time. Holesare to be centered at midslab with a tolerance of plusor minus 13 mm (1/2 inch). Dowels or tiebars start300 mm (12 inches) from the outside edge ofpavement and are spaced at 305 mm (12-inch)spacing and stop 600 mm (24 inches) from theadjacent lane to avoid hitting existing tiebars at thelongitudinal joint. It is important that the Contractordrill holes parallel to the top of the pavement and bein proper alignment or smooth dowels when installedwill not perform properly.
Smooth dowels are to be epoxy coated and 38mm (1 1/2 inch) diameter by 460 mm (18 inches) inlength. Tiebars are to be #35M (No. 11) bars whichare 460 mm (18 inches) in length and epoxy coated.Holes for dowels or tiebars are to be 41 mm (1 5/8inches) in diameter and a minimum of 229 mm (9inches) deep into the concrete.
27.1.5 Grouting Dowels or TiebarsAll dowels and tiebars are to be grouted into place
with an epoxy, polyester or vinylester resin material.
The material is to be injected pneumatically into the
back of the hole and the dowel or tiebar inserted 230
mm (9 inches) into the hole. A nylon or plastic washer
is used to retain the grout in the hole by pushing it
flush against the saw cut after the bar is installed.
Sufficient grout is to be used to completely fill all
voids around the bar including any spalling at the face
of the sawcut. Other methods of installing dowels
shall not be permitted. Most Contractors doing this
work pump the resin and hardener from pressure pots
and the two materials are mixed immediately before
being extruded into the hole. In cooler temperatures,
it may be necessary to heat the grouting mateials so
the material flows easier and sets up in the required
30 minute time period. Dowels are to be held in
proper alignment until the grout has hardened.
27.1.6 Placing, Finishing and Curing
Placement of the concrete can begin when the
grout around dowels or tiebars has hardened and after
smooth dowels are coated with a thin layer of oil or
other bond breaking material. Rigid forms are
required at the outside edge of the full depth repair.
The concrete is placed in a continuous operation and
consolidated with internal vibration. Full depth
repairs 3.0 meters (10 feet) or greater in length are to
have tied longitudinal joints in accordance with
Standard Drawing BP 2.1M (BP 2.1). Steel paving
mesh is required in repairs greater than 3.0 meters (10
feet) in length or if the repair is to be opened within
24 hours of placement. The clearance from the end of
the mesh wires to the edge of the pavement or new
transverse joint is 100 mm ± 50 mm (4 ± 2 inches).
Specifications required that repairs less than 3.7
meters (12 feet) are to be screeded longitudinally
when striking off the top of the concrete. If the repair
is over 3.7 meters (12 feet), the screed shall be
perpendicular to the center line. After screeding and
floating is completed, the surface is to be tested with a
3.0 meter (10 foot) straightedge before the concrete
hardens to assure that the transition on and off the
repair meets a tolerance of 3 mm in 3.0 m (1/8 inch in
10 feet). Any high or low areas are to be corrected and the
surface rechecked to assure compliance.
Chapter 27.0: Concrete Pavement Repairs
59
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
The surface finish of the concrete repair shall
match the adjacent concrete. If the adjacent pavement
is smooth with a burlap drag, the patch should have
the same finish. If the patch texture is different, it may
be very noticeable when traveling over the patch at
normal traffic speed.
During finishing of the patch, the Contractor has
the option of forming the joint at the transverse saw
cuts. The forming can be done by use of a hand tool
with the proper joint width and depth as shown in the
standard, or an actual wood strip of the proper
dimensions can be used as a form. The Contractor is
also permitted to finish the concrete flush with the
adjacent pavement and diamond saw the joint after
the concrete has cured and before it is opened to
traffic.
After finishing and straightedge checking is
completed, the concrete is cured with white pigmented
curing membrane as per 451.10. This section requires a
uniform coverage of membrane at an application rate of
1 liter per 3.7 square meters (150 square feet per gallon).
27.1.7 Sealing of Transverse JointsTransverse joints are to be sealed with a hot
applied joint sealer meeting 705.04. Prior to sealing
the joint, both vertical faces of the joint are to be
cleaned by abrasive blasting to the depth of the
bottom of the sealer. The cleaning shall remove all
dirt, dust, tar or asphalt, curing compound
discoloration leaving a clean dry newly exposed
surface to seal. The hot applied sealer shall be 6 mm (1/4
inch) below the surface of the pavement. A bond breaking
tape is placed at the bottom of the joint curf immediately
before the hot applied material is placed.
27.1.8 Classes of ConcreteThe pay item description for Item 255 specifies
the class of concrete. The classes of concrete used for
this item will normally be Class C, S, FS or MS.
These classes of concrete are descibed in the Manual
of Procedures for Concrete.
27.1.9 Additional RequirementsFull depth repairs can be opened to traffic when
the flexural strength of 2.7 Mpa (400 psi) is attained.
Depending on the class of concrete used and the
atmospheric conditions, the time that this strength is
obtained will vary.
When traffic is adjacent to the lane being
repaired, the Contractor is to schedule his work so
that slab replacements 18.3 meters (60 feet) and less
in length are completed within 48 hours. Repairs 3.0
meters (10 feet) and less shall not be permitted to be
left open overnight. To protect the traveling public,
repairs 3.0 meters (10 feet) or less in length in which
the pavement has been removed but not filled at the
end of the day shall be covered with steel plates. The
Contractor shall plan his work so that no repairs are
left unfilled when work is suspended for holidays or
weekends. If the Contractor has removed pavement
and is unable to complete the repairs in the above time,
he shall fill the areas with a suitable temporary patch
material to the satisfaction of the Engineer.
27.2 Thin-Bonded Patching
The success of a thin-bonded patch is dependent upon
complete removal of all unsound or damaged
material, adequate bond between old and new
concrete, use of “no slump” air-entrained concrete
and proper curing. Strict adherence to all these
requisites is necessary for successful patching.
The limits of the damaged area first must be
determined and the area to be repaired established
beyond the affected area into sound concrete. A steel
rod or steel chain may be used to sound the surface to
determine hollow and unsound areas. The area
generally should be rectangular in shape and the
perimeter should be outlined by sawing to a depth of
approximately 25 mm (1 inch) to avoid feathered
edges which usually result in spalling. Additional saw
cuts within the outlined area will aid the breakup and
Manual of Rigid Pavement Practices
60
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
removal operation. Care should be exercised to
avoid sawing through the reinforcing since this is to be
a surface patch using the existing reinforcement. If the
steel is cut, the repair will have to be more extensive
since it will be necessary to install tiebars along the
vertical faces.
Removal may be accomplished by the use of air
hammers or other suitable equipment, to such depth
that includes all deteriorated material and exposes
sound concrete. Generally, it is desirable to remove all
concrete above the reinforcing so that the steel can be
inspected and corrected, if needed, and a patch of
substantial thickness will result. If the damage is the
result of insufficient cover over the reinforcing steel,
the concrete should be removed below the steel so that
it can be lowered before replacing the concrete. This
will result in obtaining the minimum cover and correct
the cause of deterioration.
The area should be cleaned of all loose material,
dirt, dust, etc., by flushing with water or blowing out
with compressed air. If water is used, it must be
mopped out thoroughly before abrasive blasting.
Abrasive blasting of the bonding surfaces must be
done after the area has dried.
A neat cement grout of non-air-entraining
cement and water having a consistency of a thick
paint should be brushed into the cleaned bonding
surface of the exposed concrete. Care should be
exercised to see that:
1. The surface is damp but free of surface water
when the grout is applied.
2. The grout is brushed into the surface to displace
all air films and to provide a uniform thickness
of 2 mm to 4 mm (1/16 to 1/8 inch).
3. The grout is not placed so far in advance that it
dries out before being covered with the patching
material.
The principal requirements of the concrete to be
used for patching are that it have only enough water
to make it cohesive and that it have sufficient air
entrainment. The use of “no slump” concrete is
necessary to avoid shrinkage upon drying and
hardening, thereby obtaining good bond with the
adjoining concrete. An adequate amount of entrained
air is vital if the concrete is to be durable. Therefore, a
minimum of 6 percent air content should be maintained
in the plastic concrete.
When feasible, concrete meeting the
specification requirements for pavement concrete
should be used. However, when this is impractical
due to a thin patch, it may be necessary to use small
coarse aggregate concrete or mortar only. When used,
these mixes shall have a minimum of 390 kg (658
pounds) of cement per cubic meter (cubic yard) and
an air content greater than 6 percent. It is desirable to
use high-early-strength cement in all concrete for
thin-bonded patching.
After the concrete is placed, it should be
consolidated thoroughly by use of a vibrating screed
or a vibrating plate, except where the patches are
extremely small, such as at spalls. Vibration is vital
for consolidating the “no slump” concrete. The
surface must be screeded to meet the adjoining
surfaces and immediately textured and cured.
Texturing is necessary to provide a skid resistant
surface and to blend with adjoining surface
appearance. With low slump concrete it is important
to apply membrane curing immediately after finishing
and texturing to prevent loss of moisture necessary for
strength. White-pigmented membrane is required.
The repaired area shall be protected from traffic
for a minimum of 8 hours. Where possible, protection
longer than the minimum is preferable. However,
when repairs are made on pavements and structures
subjected to traffic, it is desirable to remove
barricades as soon as possible. Planning the concrete
placement for early in the day and curing the
minimum of 8 hours will permit opening the same
day. The thin patch is supported by the underlying
existing concrete, gains strength quickly due to the
low water-cement ratio and should not be damaged by
traffic with this minimum curing.
Chapter 27.0: Concrete Pavement Repairs
61
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
Checklist for Inspection of Concrete Pavements
Subgrade1. Observe proof rolling or final rolling.
2. Remove and replace with suitable material any
unstable areas noted, and recheck.
3. Check for compliance with subgrade
tolerances.
Subbase1. Subbase with materials should be uniformly
spread.
2. Width of subbase placed should be at least 300
millimeters (12 inches) wider than the pavement
on both sides.
3. Material should have moisture content as
determined by the Engineer.
4. Observe compaction of subbase.
5. Make density determinations.
6. Correct unstable areas noted.
Forms1. Prepare grade for forms — should be a slight
removal of subbase material.
2. Forms should be clean and in good condition.
3. Set forms — should be uniformly supported —
no shimming.
4. Securely fasten form locks.
5. Drive form pins and securely lock them in pin
pockets.
6. Check alignment of forms — correct if
necessary.
7. Check forms for tolerance — 3 millimeters in
3.0 meters (1/8 inch in 10 feet) for top; 6 mm in
3.0 meters (1/4 inch in 10 feet) for vertical face.
8. Check width between forms. (See Plan line sheets.)
Fine Grade1. Sprinkle subbase prior to fine grading to
maintain desired moisture content.
2. Subgrader should be cutting rather than filling.
3. Observe operation of pin templet — correct
irregularities.
4. Subbase should be rerolled with light or medium
roller to restore surface density.
5. Make final density tests and thickness
determinations.
6. Remove excess subbase material along inside of
forms to full depth of forms.
7. The ideal time to observe the forms for deflection
or side movement is during the operation of the
sub-grader, since it is usually one of the heaviest
pieces of equipment operated on the forms. Any
deviations noted in the forms during its operation
should be corrected before placing concrete in the
area.
8. Recheck alignment and grade of forms.
Final Preparation for Concrete1. Install hook bolts where required — securely
fasten to forms at correct elevation. See
Standard Drawing BP-2.1M (BP-2.1).
2. Spray forms with light oil to prevent bond.
3. Install dowel assemblies. They should be
uniformly supported and securely staked using a
minimum of eight steel pins 13 mm diameter by
460 mm (1/2 in. diameter by 18 in.). When sand
subbase or material that may distort or settle is
62
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
used, six bearing plates approximately 125 mm (5
inches) square are required under each assembly.
See Standard Drawing BP-2.2M (BP-2.2).
4. Check alignment of dowels with adjustable A-
frame level or other suitable device. Dowels
should be parallel with the surface and with the
centerline of the pavement. (This is perhaps one
of the most critical phases of inspection since
the proper performance of the joint is dependent
upon the correct alignment of every dowel in the
joint assembly. One dowel out of alignment may
prevent the entire joint from functioning.)
5. At least one half (the free end) of every dowel
should be uniformly oiled to prevent bond.
Avoid excess application. See Standard Drawing
BP-2.2M (BP-2.2).
6. Position expansion caps on oiled ends of
expansion joint dowels.
7. Accurately mark location of all joint assemblies
for sawing joints.
8. Sprinkle subbase just prior to placing concrete
to prevent absorption of water from the
concrete.
9. Remove shipping wires from dowel basket
assemblies immediately prior to placing
concrete.
Placing Concrete1. Avoid access spillage of batches when charging
concrete spreader.
2. Check minimum mixing — 60 seconds for
central mixers —70 revolutions at mixing speed
for transit mixers.
3. Make entrained air, slump and yield
determinations and adjust to within specified
tolerances. Tests should be made immediately
after placing concrete within the forms. Never
incorporate into the work any concrete that
exceeds the maximum slump or contains less
than the minimum amount of entrained air.
(Entrained air and slump are both important for
obtaining durable concrete, but entrained air is
the most vital requirement for concrete to be
resistant to the effects of freezing and thawing
and its importance cannot be over emphasized.)
4. Concrete should be spread uniformly on the
subbase.
5. Spreader should be used to distribute concrete to
full width without voids.
6. Spreader should strike off concrete at proper
depth for positioning mesh within the specified
zone. See Standard Drawing BP-1.1M (BP-1.1).
7. Tiebars for longitudinal joints should be placed
at mid-depth of slab-check position periodically.
See Standard Drawing BP-2.1M (BP 2.1).
8. Concrete should be vibrated along the full length
of all expansion joint assemblies.
9. Prohibit workers from walking on assemblies
while vibrating or when placing mesh.
10. Paving mesh should be positioned within
specified clearance at forms and at joints. See
Standard Drawing BP-1.1M (BP-1.1).
11. A minimum overlap of 300 mm (12 inches) is
required when joining sections of mesh within a
slab transversely.
12. Laps are required to have four fasteners to hold
mesh pieces together. This requires a minimum
of four ties in a 3.6 meter (12-foot) width of
mesh.
13. Concrete should be placed, spread, and struck
off for the top course.
14. If vibrators are mounted on a spreader, they
should be shut off when spreader stops.
15. If mesh is placed by vibratory method,
periodically check depth and clearance at
transverse joints. Revert to two-course method
at expansion joints and when abutting an
approach slab or existing pavement.
16. Movement of the mesh in the direction of paving
has been noted, especially when the vibratory
63
Checklist for Inspection of Concrete Pavements
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
method of mesh placement is used. It is
important that periodic checks be made to assure
that the clearance is maintained at all transverse
joints.
Finishing1. Machine finishing should be delayed as long as
it is practical to permit consolidation of the
concrete.
2. A roll of concrete should be maintained ahead of
all screeds at all times. The roll should be at
least 100 mm (4 inches) but not more than 250
mm (10 inches) and should be uniform.
3. First screed should be tilted slightly to provide
compaction and surge.
4. The entire surface should be straightedged using
straightedges at least 3.0 meters (10 feet) in
length.
5. If floats of any types are used, they should
precede the straightedging or the surface should
be rechecked with the straightedge.
6. Caps protecting preformed expansion joint
material should be removed as concrete sets and
the joint should then be hand finished.
7. Prohibit the use of water on the surface of the
concrete to aid in finishing. (This practice results
in an increase in the water-cement ratio and a loss
of entrained air of the surface concrete, thereby
decreasing its durability. Surface scaling can
usually be traced to these areas.)
8. Edges along forms should be finished using an
edging tool.
9. Immediately prior to tine texturing transversly, a
turf drag or broom drag finish shall be provided.
The surface shall be a uniform gritty texture in
the longitudinal direction.
10. Periodic checks should be made to assure
specified texture is being obtained. Texturing
equipment should be raised from the surface
when not in use. The transverse texture should
be a relatively uniform pattern of grooves
spaced at 16 mm (5/8 inch) centers and grooves
shall be 4 mm (0.15 inches) deep and 3 mm
(0.10 inches) wide.
11. Areas above and at ends of expansion joint
material should be free of concrete.
Curing1. Just prior to applying curing membranes, station
numbers should be stenciled into the concrete.
Use “+000” (“+ 00”) stencils for Station 0 + 000
to 9 + 000 (0 + 00 to 9 + 00) only.
2. Curing membrane should be applied after the
water sheen has disappeared from the surface of
the concrete.
3. Membrane should be thoroughly agitated prior
to use.
4. Daily checks should be made to assure minimum
coverage of 1 liter per 3.7 square meters (1
gallon per 150 square feet) for 451, 452 and 453
pavement and 1 liter per 4.9 square meters (1
gallon per 200 square feet) for 305 base.
5. After removal of forms, membrane should be
applied to the pavement edges. Any surface
membrane which has been broken or damaged
should be touched up at this time.
Joints1. Standby saw in operating condition should be
maintained on project during sawing operations.
2. Center of transverse joints should be established
from previously placed marks.
3. Sawing of transverse joints should be done
before the concrete cracks but without excessive
raveling. The timing of the sawing is critical and
varies with temperatures and materials used.
Close attention is necessary to avoid random
cracking.
4. If random cracking occurs while sawing a
transverse joint, immediately cease sawing at
Manual of Rigid Pavement Practices
64
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
that joint and move ahead three to five joints.
Resume sawing the joints at that interval until
caught up with rate of hardening. The intervening
joints may then be sawed without random
cracking.
5. Timing of longitudinal joint sawing is not as
critical; however, they should be sawed within
three days.
6. Saw cuts should be straight and perpendicular to
the surface of the pavement.
7. Saw cuts should be cleaned immediately after
sawing by a jet of water under pressure. If
sawing is being done dry, compressed air may
be used in lieu of water.
8. Depth and width of saw cut should be checked
periodically. Transverse joints and longitudinal
joints shall have minimum depth of 1/4 of the
slab thickness for pavement less than or equal to
255 mm (10 inches) and 1/3 of the slab
thickness if the pavement is greater than 255
mm (10 inches). The width of the saw cut shall
be 6 ± 1.6 mm (1/4 ± 1/16 inch) determined at
the time of sawing.
9. Joint openings should be filled as soon as
practical.
Sealing1. All joints should be sealed prior to opening to
traffic or to use by construction equipment.
2. Joints should be cleaned just prior to sealing by
operating a saw blade backwards through the
joint.
3. Joints should be further cleaned by means of a
water jet or compressed air and should be clean
and dry when sealer is placed.
4. Joints should be filled flush when liquid fillers
are used. Preformed sealers should be
approximately 6 mm (1/4 inch) below the
surface.
5. All underfilled joints should be resealed and all
excess and unsightly sealer should be removed
before final acceptance.
EquipmentWhile it is not the duty nor the right of the
Inspector to adjust the Contractor’s equipment, he
should satisfy himself that all the necessary
equipment is on the job, placed on the forms, and
adjusted. The Inspector should observe the
Contractor’s personnel making the checks, and
adjustment if needed, for all screeds and pan floats
prior to placing concrete.
All equipment should be synchronized so that
each machine leaves the concrete in the proper
condition for the machines that follow. The last
machine may not be doing its job properly due to
improper adjustment of the previous one.
An approved spreader is required when the
width of pavement being placed in one operation is
3.6 meters (12 feet) or greater and the total square
meters (square yardage) of any given width exceeds
8,300 (10,000).
A self-propelled concrete finishing machine is
required for compacting and finishing the concrete. If
the finisher has two screeds, they shall be
independent-ly operated. If the finisher has only one
screed, the screed shall be not less than 460 mm (18
inches) in width and shall have compensating springs to
minimize the effect of momentum of the screed on the
side forms.
Central mixers and transit mixers may not
exceed the manufacturer’s rated capacity. Minimum
mixing shall be 60 seconds for central mixers and 70
revolutions at mixing speed for transit mixers.
Checklist for Inspection of Concrete Pavements
65
Item 453 - Continuously ReinforcedConcrete Pavement
Pay Unit - Square Meter (Square Yard) -
Continuously Reinforced Concrete Pavement
Item 611 - Approach SlabsPay Unit - Square Meter (Square Yard) -
Reinforced Concrete Approach Slabs
Documentation Forms for Items 305, 451, 452,
453 and 611:
D-1 C-119 Inspector’s Daily Report
D-2 Reverse Side of C-119, calculations,
sketches, etc.
D-3 C-145 Rigid Pavement Daily Report
D-4 TE-45 Concrete Inspector’s Daily
Report
D-5 Reverse Side of TE-45 Report
Method of measurement for Items 305, 451, 452,
453 and 611:
Square meters (square yards) calculated from
verified plan dimensions.
Documentation Procedures
It is the intent of this section to recommend minimum
documentation requirements by combining and/or
eliminating various inspection forms now in use and
still document information in sufficient detail to
verify that construction is in substantial conformity
with the proposal, plans and specifications.
See D-1 thru D-6 for samples of forms discussed in
this section.
Item 305 - Portland CementConcrete Base
Pay Unit - Square Meter (Square Yard) - Portland
Cement Concrete Base
Item 451 - Reinforced Portland CementConcrete Pavement
Pay Unit - Square Meter (Square Yard) -
Reinforced Portland Cement Concrete Pavement
Item 452 - Plain Portland CementConcrete Pavement
Pay Unit - Square Meter (Square Yard) - Plain
Portland Cement Concrete Pavement
66 STATE OF OHIO DEPARTMENT OF TRANSPORTATION
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
Glossary of Words or Terms as Applied to the Rigid Pavement Section ofthe Manual of Construction Procedures
Admixture - A substance other than cement, water
or aggregate added to a batch of fresh concrete to
alter one of the normal properties of concrete.
Aggregate - Mineral material, such as sand, gravel,
crushed stone, slag, or the combination thereof,
with which cement is mixed to form a mortar or
concrete. “Fine aggregate” may be considered as
the material that will pass a 4.75 mm (No. 4)
screen, and “coarse aggregate” as the material that
is retained thereon.
Batch - The combination of amounts of cement,
aggregate, water and admixture which will be
mixed at one time in a mixer.
Batching Plant - The plant either on or off the work
site where the materials are assembled by batches
for the mixer. Water and admixtures usually are
added as the batch is introduced into the mixer.
Beam, Test - A beam of specified size molded on
the job and later broken in a testing machine to
determine the flexural strength of the concrete.
Bleeding - Flow of water to the surface of freshly
placed concrete.
Cap - A short tube, closed at one end, placed on the
oiled end of a dowel in an expansion joint to
provide space for movement of the dowel in
hardened concrete. A stop in the tube prevents it
from being pushed all the way onto the dowel
before the concrete hardens.
Cement - A mixture of clay, limestone and other
selected materials heated to high temperature and
ground into powder. Mixed with water it forms a
paste to surround and bind the aggregate into a solid
and durable mass.
Change Order - A written order issued by the
Director to the Contractor, covering changes in the
plans or quantities or both, within or beyond the
scope of the contract and establishing the basis of
payment and time adjustments for the work affected
by the changes.
Contraction Joint - A joint which controls the
location of a transverse crack and permits the slab to
contract and expand with changes in temperature.
Contractor - The individual, firm or corporation
contracting with the Ohio Department of
Transportation for the performance of prescribed
work, acting directly or through a duly authorized
representative and qualified under provisions of the
law.
Construction Joint - A joint formed in concrete
pavement at the end of the day’s production or any
time production is interrupted for 30 minutes or
longer.
Core - A cylinder of concrete cut from pavement
with a hollow drill. Cores are 200 mm (4 inches) in
diameter and are used to check the thickness and
strength of the concrete.
Course - The depth of concrete pavement obtained
in one pour.
Crown - The height of the center of the roadway
surface above a straight line drawn between its
edges.
Cure - The treatment given concrete to assure
sufficient water and heat necessary for chemical
action so that concrete attains the strength and
durability for which it was designed.
72
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
Curing Membrane - A compound sprayed over the
exposed surface and edges of newly placed
concrete to prevent the evaporation of water during
curing.
Cylinder - A test sample of concrete molded into a
cylinder 600 mm (12 inches) high and 300 mm (6
inches) in diameter, to be sent to the Laboratory for
determination of strength and density.
Deformed Bar - A steel bar which has projections
on its surface for increasing the bond between the
concrete and the bar.
Density (Soil) - The density of soil is its weight-
volume relationship, which usually is expressed in
kilgrams of soil per cubic meter (pounds of soil per
cubic foot).
Department - The Ohio Department of Transportation.
Director - The Director of Transportation, the
Assistant Director of Transportation, the Deputy
Director of the Division of Highways, the Deputy
Director of the Division of Urban Mass
Transportation, the Deputy Director of the Division
of Aviation, the Chief Engineer of the Division of
Highways, the Highway Construction
Administrator, the Operation and Maintenance
Administrator, the Highway Design Administrator,
the Engineer of Construction, the Engineer of
Maintenance, the Engineer of Bridges, or the
Engineer of Tests.
Documentation - Recording and filing evidence
that the material or work is in conformance with
specifications in the amounts determined.
Dowel or Dowel Ba r - A smooth steel bar
extending across a concrete joint to transfer the
applied load, prevent future misalignment of the
slab and permit movement at the joint.
Dowel Assembly - A cage or basket used to hold
dowels in position during placement of concrete.
Edging - Rounding the edges of concrete pavement
and hand-formed joints while the concrete still is
workable, using an edging tool of specified radius.
Elevation or Grade - The height as measured
from a predetermined point denoted in the
plans.
Engineer - The District Deputy Director of
Transportation, the District Construction Engineer,
the District Operations Engineer, the District
Testing Engineer or the Project Engineer assigned
to administer the contract.
Expansion Joint - A joint adjacent to a bridge or
intersection to absorb expansion of concrete
pavement and prevent expansive pressure on the
bridge or intersecting pavement.
FHWA - Federal Highway Administration, U.S.
Department of Transportation.
Fine Grading - Removing approximately 25 mm (1
inch) of the primary subbase and rerolling to bring
to exact grade, upon which the concrete pavement
is placed.
Finishing - Shaping the surface of concrete that is
not shaped by forms. Also it includes filling visible
voids in the concrete after the forms are removed.
Finishing Machine - A machine which screeds and a
float for performing the final grade and smoothness
of the concrete pavement to meet the requirements.
Float - A straight piece of wood or metal used to
smooth the surface of plastic concrete. Small hand-
held floats are called paddle floats.
Forms, Pavement - Metal plates secured together
and to the subbase for shaping the sides of the
pavement and controlling alignment, grade and
thickness. Also, the forms serve as a track for
paving equipment.
Grade (noun) - See Elevation.
Grade (verb) - To add or remove earth to obtain a
desired level or slope.
Hand Finishing - Correcting manually irregularities
left by the finishing machine or performing those
functions which cannot be accomplished by machine,
such as edging or forming of joints.
73
Glossary
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
Head - The roll of plastic concrete which forms
ahead of a screed plate.
Honeycombing - Large voids in the concrete which
are due to inadequate spading or consolidating.
Hook Bolt - A short steel bar with hooked ends
joined by a threaded connection. Use is to fasten a
concrete slab to another later constructed beside it.
Inspection - Examination by observation,
measurement, or tests to determine that materials
and work are in conformance with specifications.
Joint Lock - The device at each end of a section of
paving form for attaching the sections together.
Job Control - Steps taken to keep quality and
quantity of materials and work on a project within
the specifications and plans.
Joint Sealer - A compound for preventing entrance
of water and solid particles into a joint. The sealer
may either be preformed or liquid.
Laboratory (Laboratory with “L” capitalized) -
Testing Laboratory of the Department of
Transportation, 1600 West Broad Street,
Columbus, Ohio 43223. If reference is to the
District laboratory, it is so designated.
Laitance - An accumulation of fine particles on the
surface of freshly placed concrete occurring when
there is an upward movement of water through the
concrete due to the presence of too much mixing
water or excessive vibration.
Lane or Traffic Lane - A strip of pavement of
specified width, usually 3.6 meters (12 feet).
Longitudinal Joint - A joint which extends
lengthwise in the roadway, parallel to the
centerline.
Mesh - A fabric of steel wires welded together at
their intersections for placement in concrete
pavement as distributed reinforcement.
Mesh Installer - A machine for imbedding wire
mesh into freshly placed concrete pavement.
Mortar - A mixture of water, sand and cement.
Mixed with coarse aggregate, this mortar
completely envelopes each particle of coarse
aggregate to form concrete. Also, mortar is used to
fill honeycombing which becomes apparent upon
removal of forms.
Oscillating - To swing back and forth, operating
between fixed limits, such as the movement of a
screed on a finishing machine.
Pin Template or Templet - A device used to check
the surface of the subbase.
Plans - The plans, profiles, typical cross sections,
working drawings and supplemental drawings,
approved by the Director, or exact reproductions
thereof, which show the location, character,
dimensions, and details of the work.
Project - The specific section of the highway
together with all appurtenances and construction to
be performed thereon under the contract.
Project Engineer - The person representing the
Department who is charged with the overall
responsibility at the project site for seeing that
construction is in conformance with plans and
specifications, and that all checks for job control
and validation of pay items are documented and
filed properly.
Proposal - The offer of a bidder, on the prescribed
form properly signed and guaranteed, to perform
the work and to furnish the labor and materials at
the prices quoted.
Raveling - Slightly disturbing the surface of
concrete pavement adjacent to sawing of a joint.
Random Cracks - Cracks which appear in concrete
pavement due to contraction in the early stages of
curing, and which follow no set pattern.
Rigid Pavement Inspector - An authorized
representative of the Engineer to make detailed
inspections and documentation of contract
performance as pertain directly to concrete paving
operations.
Manual of Rigid Pavement Practices
74
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
Sawing - Using a circular saw to cut a groove in the
surface of the pavement to control the location of
transverse cracks.
Scaling - Peeling away of small amounts of the
concrete surface.
Screed - A long metal plate moved across the
surface of freshly placed concrete with a sawing
motion to consolidate the concrete and rough finish
it approximately to grade.
Segregation - The unintentional separation of the
larger pieces of aggregate from the smaller pieces
within one size of aggregate or within a mixture of
sizes of fresh concrete.
Shim - A thin piece of stone, wood or other material
used to raise the object resting on it to the desired
elevation. (Not permitted in adjusting forms to
grade.)
Slab - A continuous portion of concrete paving
bounded by joints and/or the edge of the pavement.
Slip Form Paving - Concrete paving by use of a
machine carrying its own forms between which
low slump concrete is compacted sufficiently to
retain its shape after the machine has progressed
onward.
Slump - Measured in millimeters (inches) on a
vertical axis, the amount that a sample of fresh
poured concrete that has filled a standard inverted
cone will sink down after the cone has been
removed. A measure of the consistency and
workability of concrete.
Spading -Repeatedly inserting a flat steel blade
edgewise into fresh poured concrete for
consolidation and to drive out entrapped air,
particularly where the concrete meets the forms or
imbedded objects.
Spalling - The breaking away of hardened parts of
concrete from the main body at surface points.
Specifications - The directions, provisions and
requirements contained in the State of Ohio,
Department of Transportation Construction and
Material Specifications as supplemented by the
supplemental specifications and special provisions.
Spreader - A machine which distributes fresh
concrete generally over the area between the
forms.
Standard Drawings - The Standard Construction
Drawings issued by the Bureaus of Location and
Design, Bridges and Design Services.
Station Marker - A numeral impressed into the
surface of newly finished concrete pavement and
located at specified longitudinal intervals near the
edge of the roadway for purposes of future location
references.
Straightedging - Placing a 3.0 meter (10 foot)
straightedge on the finished pavement surface to
determine if the surface is within tolerance.
Strike Off - Using a straightedge to scrape off excess
concrete which may protrude above the mold or
forms.
Subbase - The layer of specified, compacted
material placed on the prepared subgrade to serve
as a base for pavement.
Subgrade - The portion of a roadbed upon which
the pavement structure and shoulders are
constructed after it is prepared.
Surge - The rise in the surface of plastic concrete
following the release of compaction after the
screed has passed over it.
Texturing - Slight roughening of the finished
surface of concrete pavement to provide greater
safety through increased traction to the tires of
vehicles which will pass over it.
Thin-Bonded Patching - Repairing concrete
pavement only to the depth of unsound concrete
rather than the full depth of the pavement.
Tie Bar - A deformed dowel or hook-bolt placed
across longitudinal joints of concrete pavement
near middle depth to tie the slabs together and hold
the joint closed.
Tieing - Wiring together overlapped mesh that is
hand-tied by use of rings similar to hog rings.
Tolerance - The permitted variation from a specified
condition.
Glossary
75
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
Traction Speed - The rate of forward movementparallel to the centerline by the paving equipment.
Transverse - A theoretical line runningperpendicular to the longitudinal or centerline of aroadway.
Validation - The signature or initials of anauthorized individual on any form or ticketdenoting that the information is as stated.
Verification - The steps necessary to determine thatthe work or materials described are in conformancewith plans and specifications.
Vibrator - A device for pulsating fresh concrete sothat entrapped air is released, and the concretesettles uniformly about reinforcement and to the
forms.
Wearing Plate - A small plate which drags over the
top of the pavement forms or adjacent paving to
control the height of the screed plate.
Windrow - An accumulation of material as a result
of rolling up or sliding off to the side. Applies here
to loose material just inside of the forms left by the
subgrader in the fine grading operation.
Yield - A check on the mix design made by dividing
the total batch weight by the determined weight per
unit volume. The actual volume thus obtained is
compared to the design volume.
76
Manual of Rigid Pavement Practices
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
Index
Batch Plants, Storing of Aggregate .................................................................................................... 9
Scales ..................................................................................................................................................... 9
Site Preparation ...................................................................................................................................... 9
Stock Piling ............................................................................................................................................ 9
Check List for Inspection of Concrete Pavements .................................................................... 62
Cold Weather Construction .................................................................................................................... 51
Combination Float Finisher Operation ................................................................................................ 32
Adjust to Proper Speed ............................................................................................................................ 32
Metering Concrete to Machine ................................................................................................................ 32
Setting Screeds and Float ......................................................................................................................... 32
Concrete—Moisture and Mix Control ................................................................................................... 26
Concrete Pavement Repairs ................................................................................................................... 57
Full Depth Pavement Replacement.......................................................................................................... 57
Thin-Bonded Patching ............................................................................................................................. 61
Concrete Placing and Spreading ........................................................................................................... 27
Placing on Grade ...................................................................................................................................... 27
Spreading ................................................................................................................................................. 27
Care at Joints ............................................................................................................................................ 27
Head ......................................................................................................................................................... 27
When Required ........................................................................................................................................ 27
Vibration .................................................................................................................................................. 28
Curing ........................................................................................................................................................... 43
Effect of Variable Weather ...................................................................................................................... 43
Membrane Curing .................................................................................................................................... 44
Sheeting.................................................................................................................................................... 45
Types Permitted ....................................................................................................................................... 43
77
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
Value of Adequate Cure........................................................................................................................... 43
Water Curing ............................................................................................................................................ 45
Documentation Procedures .................................................................................................................... 67
Documentation Forms.............................................................................................................................. 69
Edge Patching ............................................................................................................................................ 46
Cleaning at Joints ..................................................................................................................................... 47
Curing Edges ............................................................................................................................................ 47
Repairing Honeycomb ............................................................................................................................. 46
Field Checking ............................................................................................................................................ 37
Crown ....................................................................................................................................................... 38
Pavement Thickness ................................................................................................................................ 38
Recording Checks .................................................................................................................................... 39
Running Yield .......................................................................................................................................... 37
Final Finishing ............................................................................................................................................ 40
Edging ...................................................................................................................................................... 41
Station Numbers ...................................................................................................................................... 42
Straight Edging ........................................................................................................................................ 40
Texturing .................................................................................................................................................. 41
Form Removal ............................................................................................................................................ 46
Forms ............................................................................................................................................................ 13
Checking .................................................................................................................................................. 13
Keys and Locks ........................................................................................................................................ 13
Oiling ....................................................................................................................................................... 14
Setting ...................................................................................................................................................... 13
Glossary ....................................................................................................................................................... 71
Hot Weather Construction ....................................................................................................................... 49
Inspection Personnel Assignment ........................................................................................................ 3
Joints ............................................................................................................................................................ 15
Construction Joints .................................................................................................................................. 18
Dowels ..................................................................................................................................................... 16
78
Manual of Rigid Pavement Practices
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
Sawing...................................................................................................................................................... 20
Construction Joints .................................................................................................................................. 23
Checking Assemblies ............................................................................................................................... 17
Dowels ..................................................................................................................................................... 16
Placing Assemblies .................................................................................................................................. 16
Preventing Bond....................................................................................................................................... 17
Sawing...................................................................................................................................................... 20
Ties ........................................................................................................................................................... 17
Expansion Joints ...................................................................................................................................... 18
Caps.......................................................................................................................................................... 18
Expansion Material .................................................................................................................................. 18
Sawing...................................................................................................................................................... 20
Longitudinal Joints .................................................................................................................................. 15
Placing...................................................................................................................................................... 15
Sawing...................................................................................................................................................... 20
Ties ........................................................................................................................................................... 15
Sealing...................................................................................................................................................... 47
Sawing and Forming ................................................................................................................................ 20
Checking .................................................................................................................................................. 23
Measurement .............................................................................................................................................. 56
Mechanical Equipment ............................................................................................................................. 5
Combination Float Finisher ..................................................................................................................... 7
Mesh Installers ......................................................................................................................................... 6
Site Mixers ............................................................................................................................................... 7
Slip Form Pavers ...................................................................................................................................... 8
Spreaders .................................................................................................................................................. 5
Transit Mix and Central Mix Equipment ................................................................................................. 7
Transverse Finishing Machines ............................................................................................................... 6
Vibrators .................................................................................................................................................. 5
Pavement Cores ......................................................................................................................................... 54
Pavement Inspection ................................................................................................................................ 3
Pavement Repairs ..................................................................................................................................... 57
Full Depth Pavement Replacement.......................................................................................................... 57
Thin Bonded Patching.............................................................................................................................. 60
79
Index
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
Reinforcement ............................................................................................................................................ 24
Condition of Mesh ................................................................................................................................... 24
Handling ................................................................................................................................................... 24
Placing...................................................................................................................................................... 24
Tieing ....................................................................................................................................................... 25
Slip Form Paving ....................................................................................................................................... 34
Grade Control ........................................................................................................................................... 35
Finishing .................................................................................................................................................. 35
Placing Concrete ...................................................................................................................................... 34
Subbase .................................................................................................................................................... 34
Specifications ............................................................................................................................................. 3
Subbase ........................................................................................................................................................ 11
Fine Grading ............................................................................................................................................ 11
Moisture Control ...................................................................................................................................... 12
Pin Template ............................................................................................................................................ 12
Placing...................................................................................................................................................... 11
Rechecking Forms ................................................................................................................................... 12
Recording Checks .................................................................................................................................... 12
Subgrade ...................................................................................................................................................... 10
Preparation ............................................................................................................................................... 10
Proof Rolling ............................................................................................................................................ 10
Requirements ........................................................................................................................................... 10
Tolerance Check ...................................................................................................................................... 10
Surface Smoothness ................................................................................................................................ 55
Testing and Sampling ...............................................................................................................................52
Transverse Finishing Machine Operation ........................................................................................... 29
Care at Expansion Joints .......................................................................................................................... 31
Effect of Mix Consistency ....................................................................................................................... 30
Factors Involved....................................................................................................................................... 29
Clean Rails ............................................................................................................................................... 29
Head—Screed .......................................................................................................................................... 29
Height and Tilt ......................................................................................................................................... 29
Surge ........................................................................................................................................................ 30
Traction Speed and Stroke ....................................................................................................................... 29
Manual of Rigid Pavement Practices
80
STATE OF OHIO DEPARTMENT OF TRANSPORTATION
General Operation ..................................................................................................................................... 30
Passes Necessary ..................................................................................................................................... 30
Relation—Traction to Stroke .................................................................................................................. 31
Results to be Obtained ............................................................................................................................. 29
Work to be Performed .............................................................................................................................. 29
Index
81