SESSION 9SESSION 9

Construction Considerations

ObjectivesObjectives

Describe key aspects of:

Prepaving operations

Paving operations

Postpaving operations

Understand effects of pavement texturing

Identify benefits of initial pavement smoothness

Prepaving ActivitiesPrepaving Activities

Subgrade preparation

Base preparation

Joint layout

Subgrade PreparationSubgrade Preparation

Mixing in coarser material or stabilizer (as needed)

Fine grading and compaction

Accurate trimming to establish grade

Setting grade stakes

Base PlacementBase Placement

Joint LayoutJoint Layout

Paving ActivitiesPaving Activities

Mixing and transporting concrete

Placing concrete

Consolidating concrete

Mixing and Transporting Concrete

Mixing and Transporting Concrete

Optimize workability

Mixing time and temperature

Mix design (water, cement, gradation)

Air content Optimize finishability

Fines content Avoid segregation

In every step of mixing, handling, transporting

Placing ConcretePlacing Concrete

Placing ConcretePlacing Concrete

Consolidating ConcreteConsolidating Concrete

Remove entrapped air

Distribute concrete uniformly around the dowels and reinforcement

Avoid under / overconsolidation

Honeycombing

Bleeding

Postpaving ActivitiesPostpaving Activities

Finishing

Texturing

Curing

Joint sawing and sealing

Opening to traffic

FinishingFinishing

Screed off concrete surface level to desired height

Machine float to fill in low spots

Minimize hand finishing

Finishing too soon or too much will produce a surface with poor durability

TexturingTexturing

Initial texturing by burlap or astroturf drag behind paver

Tine texturing as soon has sheen of bleed water has disappeared

Separate machines used for tining and applying curing compound

Tine TexturingTine Texturing

Tine TexturingTine Texturing

Important for surface friction and acceptable noise levels

Transverse tining most common procedure

For reduced noise levels, grooves:

3 to 5 mm deep

3 mm wide

Variably spaced 10 to 40 mm apart

CuringCuring

Enhance hydration and strength gain

Retain moisture and heat immediately after placement and finishing

Most common method: liquid membrane-forming curing compound

Retains moisture, but not heat

Blanket insulation may also be needed

Curing CompoundCuring Compound

Joint Sawing and Sealing

Joint Sawing and Sealing

Saw to establish contraction joints

Conventional sawcut dimensions:

Depth: D/4 to D/3 typical

Width: 3 mm (0.12 in)

Lightweight saws permit shallower cuts

Widening cuts for sealant reservoir

Sawcut TimingSawcut Timing

Time

Co

ncr

ete

Set

Sawcutting “Window”

Too Late:Random Cracking

Too Early:Excessive Raveling

Joint SawingJoint Sawing

SawcutSawcut

Lightweight Sawing Equipment

Lightweight Sawing Equipment

Joint Preparationand Sealing

Joint Preparationand Sealing

HIPERPAV Computer Program

HIPERPAV Computer Program

Evaluates potential for uncontrolled cracking

Uses job-specific inputs for:

Mix design

Pavement design

Construction

Environmental factors

HIPERPAVMix Design Inputs

HIPERPAVMix Design Inputs

HIPERPAVPavement Design

Inputs

HIPERPAVPavement Design

Inputs

HIPERPAVConstruction Inputs

HIPERPAVConstruction Inputs

HIPERPAVEnvironmental Inputs

HIPERPAVEnvironmental Inputs

HIPERPAV OutputHIPERPAV Output

Initial Pavement Smoothness

Initial Pavement Smoothness

Riding comfort

Improved long-term performance

Smoothness specifications:

Improved initial smoothness levels

Total roughness per unit length

“Must-grind” bump

Incentives/disincentives

California profilograph

California ProfilographCalifornia Profilograph

Lightweight ProfilerLightweight Profiler

Opening to TrafficOpening to Traffic

Time requirements

Strength requirements

Beam or cylinder testing

Maturity methods

SummarySummary

Prepaving

Paving

Postpaving

Smoothness

Subgrade preparationBase preparation

Mixing and transportingPlacingConsolidation

FinishingTexturingCuringJoint sawing and sealing