Highway Conc. Payments

8/8/2019 Highway Conc. Payments

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PRESENTEDPRESENTED BYBY::

RAGHAVENDRARAGHAVENDRA ..SS88thth SEMSEM CIVILCIVIL

SS..JJ..CC.. INSTITUTEINSTITUTE OFOF TECHNOLOGYTECHNOLOGY

HIGHWAY CONCRETE PAVEMENTSHIGHWAY CONCRETE PAVEMENTS


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INTRODUCTIONINTRODUCTION

The cement concrete pavement maintains a very highrecognition among the engineers and the road usersalike.

Further the engineers have inherent confidence in thecement concrete material for its use in anyconstruction project.

In considering the drawbacks of the cement concretepavement type, it may be stated that it requires a very

high initial investment. A minimum period of 28 days curing is required before

the cement concrete pavement could be opened tothe traffic.


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CONCRETE PAVEMENTS - PAST, PRESENT, AND

FUTURE

The following paper prepared for the 6th international

conference on concrete Pavement Design and Materials forHigh Performance, Nov. 18-21, 1997. The entire paper waspublished in the conference Proceedings, which is availablein the May 1998 issue of Concrete International, the officialmagazine of the American Concrete Institute.


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SPECIFIC PAVEMENTSTUDIES (SPS)SPECIFIC PAVEMENTSTUDIES (SPS)

Focus on certain pavement engineering factorsFocus on certain pavement engineering factors

Primary Factors

Subgrade: fine & courseTraffic: medium & heavyTemp: freeze and non-freezeMoistures: wet and dry

Secondary Factors

AC drainage - yes, noAC thicknessAC base type and thicknessPCC strength and thicknessLane width

Base type


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The Past

As designers planning for the future, we must continuallylook back to where we have been both the mistakesmade and the lessons learned

According to Blanchard's American Highway Engineers'Handbook of 1919, in 1879 in Scotland, a concrete was

used with Portland cement for binding. "The surface wasvery good, but when the road commenced to break, itwent to pieces very fast.

Pennsylvania Department of Transportation (DOT)published a report on tests to evaluate the amount of

damage, and the repair and prevention of damage fromhorses and buggies.

In 1921 and 1922, the Pittsburgh, Calif., Road Test wasconducted The result of this test shows the advantages

of using mesh that hold the cracks together.


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In the mid-1950s, continuously reinforced concretepavements (CROP) started to gain in popularitybecause the design offered the benefit of eliminatingjoint distress.

Also in the 1950s, the slipform paver came into use. It

reduced paving trains from 100 workers down toabout 25.

The AASHO (American Association of State HighwayOfficials) Road Test was conducted at Ottawa, from1958 to 1960.


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Prestressed concrete was introduced in the late1940s and was used first in airport pavements.

In 1959 2 way presterssed slabs war used in a airfields of Texas. The 24-in (610-mm) plainpavement was replaced with 9-in (230-mm) post-tensioned slabs.


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CONCRETE PAVEMENTS AT PRESENT

Considerable research continues on rigid pavements

About 1970, the University of Texas had a long-running study to use computer technology to

analyze the dynamic behavior of pavements.

At that time, Dr. Ron Hudson said that someday hewould be able to conduct an AASHO Road Test inthe computer


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CONCRETEPROPERTIES

A good pavement designer should also be aconcrete expert. Some facts to be kept inmind are:

Quality of Cement and aggregate

Concrete properties of particular importance topavement design are: E (Modulus of Elasticity),strength, thermal expansion, shrinkage, creep, heatgeneration, and durability


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The concrete is

loaded into

trucks from the

tilting drum mixer

and then trans-ported to the

paving site.

Concrete Paving ProjectConcrete Paving Project -- August 2001August 2001


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Onsite ready-mix

concrete plant is

installed on the

construction site.

This means:

fewer trucks than usual

need to travel to and from

the site

reduced highway traffic

congestion shortened project duration



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State-of-the-art

paver first used

on 407. It can pave

up to 3 lanes at a

time.

Uses a computer-

controlled system

(Compact DBI) to

inject steel dowel

bars into the

concrete.


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Concrete finishers

follow the paver

with bullfloats to

ensure the highest

quality finish.

Edges of the road

are finished by

hand.


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THE FUTUREWith a brief background on PCC pavement history

The following thoughts are concerned more with theconstruction process of our more standard designs.Broadly, they deal with:

making pavements more economical to construct, Speeding up the construction process to reduce traffic

delays

ON-GRADE ULTRASONIC MIXERS

In the 1960s, Ohio State University experimentedwith ultrasonic concrete mixers in which the waterthoroughly wetted the aggregate as it movedthrough a pipeline subjected to ultrasonicfrequencies.


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SELF-COMPACTING CONCRETECONCRETE

Self-leveling mixtures are already being used forsub-floors. Vibrators and their associated problems during

construction (broken vibrators, vibrator trails,etc.) would be eliminated.

SELF-CURING CONCRETE

It should be possible to develop an-oil, polymer, orother compound that would rise to the finishedconcrete surface and effectively seal the surfaceagainst evaporation.

Most paving mixtures contain adequate mixing waterto hydrate the cement if the moisture is not allowedto evaporate


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HIGH-STRENGTH CONCRETE

High-strength concrete is already being used inrapid-cure patches.

No advantages to using higher strengths inpavements.

R.K. Dhir recently published some test results onself-curing mixtures.


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CONCRETEPAVEMENTS WITHOUTSUBBASESFOR LIGHTTRAFFIC FACILITIES

The need for a subbase - a layer of granular material placedon a prepared subgrade - depends on the frequency of heavytruck loadings.

The function of a subbase is to prevent: pumping of finegrained, subgrade soils.

In the absence of heavy truck traffic, which is the case formany streets, secondary roads, and parking lots, a sub-baseis not needed.


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Composition of new roadbed:

150 mm (6") subbase consisting of recycled, previousasphalt pavement 150 mm (6") of clear granular (granular O) for drainage

purposes 200 mm (8") of concrete

This project requires the building of 64 drainage culvertsand the rehabilitation of one overpass (in asphalt).


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CONCLUSION

We must continue to build on the wealth of availableresearch on pavements

The research needs for the future are being looked at,primarily from the materials and construction point of

view. If PCC pavement construction is to stay competitive,

ways must be found to place concrete moreeconomically, with less delay to the traffic,

Fast-setting concrete that is self-leveling, self-curing,

durable, and without entrained air so that all pavingoperations can be completed within the trailing forms.The use of high-strength concrete, if it is to beeconomical,


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Thank YouThank You

Highway Conc. Payments

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