Asphalt Pavement Evaluation South Carolina Roadway Inspection Certification School

PROJECT SELECTION SCDOT Problem: more needed road repairs than available funding „ Which roadways are selected for work? „ Pavement management „ Pavement evaluation „

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Project Selection „

Consider the all of the following when choosing the best alternative: ‹ pavement distress type ‹ pavement distress amount ‹ pavement distress severity ‹ pavement smoothness ‹ structural adequacy ‹ initial cost ‹ “life cycle” cost

Pavement Management “ A decision making system which integrates planning, data collection, design construction, and maintenance.” A tool to assist in the selection of the most costeffective maintenance, rehabilitation or reconstruction alternative for a specific roadway.

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Pavement Management „

System components ‹ Prepared system map ‹ Sections or segments defined ‹ Section components - soil, pavement, etc.

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Condition survey ‹ Documents section condition

Pavement Life Cycle Theory Maint

Rehab

Reconstruct ~$1.00/SY

Condition (PCI)

>$10.00/SY

PCI = 70 - 60?

Time

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PSI/PCR versus ESAL Pavement Serviceability Rating (PSR) „ Pavement Serviceability Index (PSI) „ Pavement Condition Rating (PCR) „ Pavement Condition Index (PCI) „

Asphalt Pavement Rating Form (IS-169)

Major Defect =10 Minor Defect = 5

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Distress Causes Wheel Loads „ Environment „ Poor Drainage „ Material Deficiencies „ Construction-related Deficiencies „ External Causes(utilities, ect.) „

Asphalt Pavement Distress Cracking „ Distortions „ Disintegration „ Skid Hazards „ Surface Treatment Distress „

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Cracking Linear Cracking „ Reflective Cracking „ Edge Cracking „ Block Cracking „ Alligator Cracking „ Slippage Cracking „

Linear Cracking „

Low Temperature Cracks

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Linear Cracking „

Wheel Path Load-related Cracking

Reflective Cracking Generally Occurs over PCC Concrete Pavements „ Movement in Underlying Layers „

‹ Vertical, in response to dynamic loads ‹ Horizontal, in response to temperature

variations „

Can Occur over Cement or Fly-Ash Treated Subgrades

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Reflective Cracking

Edge Cracking „

Settlement of Underlying Material ‹ Improper

Construction ‹ Poor Drainage ‹ Frost Heave ‹ Shrinkage or Drying-out of soil „

Aggravated by Heavy-traffic, vegetation

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Block Cracking „

Low Asphalt Content Mix ‹ Insufficient asphalt ‹ Absorptive Aggregates

Block Cracking

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Hard Asphalt

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Alligator Cracking „

Excessive Surface Deflection ‹ Weak Base or Subgrade ‹ Thin Surface or Base ‹ Poor Drainage ‹ Overloading

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Progresses to Potholes in Thin Pavements

Alligator Cracking

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Slippage Cracking „

Lack of Good Bond Between Layers ‹ Dust, Oil, Dirt, Rubber, water and other non-

adhesive materials ‹ Insufficient or Absence of Tack Coat ‹ High Sand Content Mixtures ‹ Insufficient Compaction

Slippage Cracking

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Pavement Distresses Solutions Depends on both the Type and Severity of Distress „ Proper Preventive and Routine Maintenance Minimized Future Problems and Reduces Costs „ Distress Identification is Critical „

Pavement Distress „ Solutions ‹Cracking ) Route

and Seal ) Surface Treatments ) Patch ) Thin Overlay ) Remove and Replace

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Asphalt Pavement Distress Cracking „ Distortions „ Disintegration „ Skid Hazards „ Surface Treatment Distress „

Distortions Rutting „ Corrugations „ Depressions „

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Rutting „

Consolidation or Lateral Movement ‹ Subgrade or Base ) Insufficient

Compaction ) Weakened by Moisture ) Insufficient thickness ‹ Asphalt Surface ) Insufficient

Compaction ) Weak, Unstable Mix • Low voids • Excess Sand • Excess Asphalt

Rutting in Subgrade or Base original profile asphalt layer weak subgrade or underlying layer

subgrade deformation

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Rutting in Subgrade or Base

Rutting in Asphalt Layer original profile weak asphalt layer shear plane

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Rutting in Asphalt Layer

Pavement Distress „

Surface Deformation ‹ Corrugation (Wash Boarding) ‹ Stopping or Turning Traffic ‹ Down Grade Braking ‹ Poor Mix Design ) too

much asphalt ) improper gradation

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Pavement Distress „

Solutions ‹ Surface

Deformation ) Surface

Profiling ) Mill Defective Layer ) Rut Filling ) Remove and Replace Mat

Asphalt Pavement Distress Cracking „ Distortions „ Disintegration „ Skid Hazards „ Surface Treatment Distress „

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Disintegration „

Weathering, Raveling ‹ Weathering - Entire Surface ‹ Raveling- Wheel Paths

Raveling Insufficient Compaction „ Construction in Cold or Wet Weather „ Dirty Aggregates „ Insufficient Asphalt „ Overheating Mix „

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Disintegration „

Potholes (Causes) ‹ Localized Pavement Disintegration ‹ Insufficient Asphalt content ‹ Insufficient Asphalt

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Potholes (Solutions) ‹ Cold Mix Patch ‹ Full Depth Hot Mix Patch

Asphalt Pavement Distress Cracking „ Distortions „ Disintegration „ Skid Hazards „ Surface Treatment Distress „

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Bleeding

Pavement Distress „

Solutions ‹ Surface Defects ) Seal

Weathered Surfaces ) MillMill-off Flushed Mat ) Sand Blotter ) Thin Overlay

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Moisture Damage „

Stripping

Pavement Smoothness Driving Public’s “Seat of the Pants” Measure of Quality

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Structural Adequacy

Is pavement thick enough for number of loads?

Pavement Evaluation „

Consider the all of the following: ‹ pavement distress type ‹ pavement distress amount ‹ pavement distress severity ‹ pavement smoothness ‹ structural adequacy

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Asphalt Pavement Distress Questions? Thank You!

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