session 9 construction considerations. objectives describe key aspects of: prepaving operations...
Post on 18-Jan-2016
228 Views
Preview:
TRANSCRIPT
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
top related