1. PAVEMENT MAINTENANCE 1:
Part 2: Distress Identification
Idaho Roads
Scholar Program

2. Learning Objectives Recognize Asphalt Pavement Distresses
Know the Causes of Main Types of Distress
Determine Which Pavements are Good Candidates for Pavement Preservation

3. What pavement characteristics indicate pavement condition?
Visible performance indicators
Functional indicators
Structural indicators
Non-Visible defects
Environmental effects on materials
Load-related damage
First, let’s define what we mean when we say pavement “condition.” Typically a discussion of pavement condition is thought of what you can see on the pavement surface. But as we have indicated, what you don’t see can be more or as important in determining where the pavement is on its deterioration curve.
Visible performance indicators are those functional and structural indicators that are 1) visible on the surface, and 2) measurable.
Functional performance is ride and safety. Aspects of ride quality include smoothness and noise; safety includes friction, removal of standing water. What are some indicators of pavement functionality? Rough ride, wet weather accidents, standing water, noise. Ride quality, surface friction, and surface drainage.
Structural performance refers to the load carrying ability of the pavement. We can look at this indirectly by measuring the pavement response to loads or by testing the overall strength of the pavement or the strength of its individual layers. We also see signs of a pavement’s structural capacity in the distresses visible at the pavement’s surface. Distress (cracking and rutting) and surface deflections.
However, pavements begin to deteriorate long before they show any visible distress. That is, environmental conditions (temperature cycles and moisture infiltration) and repeated load applications cause incremental damage to pavement layers. This cumulative damage eventually results in visible pavement distress.

4. What techniques are used to assess pavement condition?
Visual distress surveys
Roughness surveys
Friction surveys
Drainage evaluation
Shoulder surveys
Deflection testing
With these performance indicators in mind, what types of field surveys can be used to assess these performance conditions?
Contrast project level with network level. In PMS, these are project level surveys, done when the network level survey has triggered potential projects. All of these survey types give useful information when deciding on whether or not to apply preventive maintenance, as well as when selecting appropriate PM techniques.
Visual distress surveys give an indication of current functional and structural conditions. Type, severity, and extent of visible distress is recorded. The visible distress types give an indication of .
Roughness and friction surveys are functional-related.
Drainage evaluations can be helpful in preventing structural problems.
Deflection testing can be used to provide information regarding the structural condition at specific points.

5. Progression of Pavement Deterioration
In order to apply appropriate PM at the optimal timing, one must first have a good understanding of the typical progression of pavement deterioration for both HMA and PCC surfaced pavements.
What must be stressed is that no matter how well-defined and well-constructed a pavement is, it will deteriorate over time as a function of repeated climatic cycles and traffic-related applications.
When trying to determine appropriate PM, it is important to ask yourself “How do I expect my pavements to perform?” You should have a feel for the typical performance of a pavement in your state given a particular location (climate) and traffic.
Point out that variation is great in performance due to changes in many characteristics: environment, design, construction, etc.

6. Pavement Distress Categories
Load
Example: Fatigue Cracking
Climate
Example: Weathering/Raveling
Other
Construction

7. Load Related Distresses
Fatigue Cracking
Potholes
Rutting
Edge Cracking
Shoving

8. Fatigue Cracking Possible Causes Bottom-up cracking Weak base/subgrade
Thin pavement / under designed
Poor Drainage
Overloading
Bottom-up cracking

9. Fatigue Cracking

10. Fatigue Cracking

11. Longitudinal/Transverse Cracking

12. Washington State - Top-Down in Asphalt Pavements > 150 mm

13. M3 2
TRL
M32 CORE

14. Rutting In Subgrade/Base In the AC Layer Design Problem
Plastic Flow--Material/Mix Design
Consolidation--Compaction
Surface Wear

15. Rutting

16. Rutting

17. Rutting in Subgrade/Base
original
profile
weak subgrade or underlying layer
asphalt layer
subgrade
deformation

18. Rutting in Asphalt Layer
original
profile
weak asphalt layer
shear plane

19. Rutting in Asphalt Layer
original
profile
Wheel path consolidation
Improper compaction

20. Potholes Severe, uncorrected result of another distress
Alligator Cracking
Raveling
Failed Patches
Thin/Weak Pavement

21. Potholes

22. Potholes

23. Edge Cracking Poor lateral support Settlement of underlying material
poor drainage
frost heave
shrinkage/drying of soil
Aggravated by high traffic levels

24. Edge Cracking

25. Shoving “Washboarding” Occurs at high stress locations
Intersections
Steep Grades
Ramps
Weak unstable mix
Unstable base

26. Shoving

27. Climate Related Distresses
Block Cracking
Joint Reflective Cracking
Thermal Cracking
Weathering/Raveling

28. Block Cracking Divides the pavement into rectangular pieces
1ft x 1ft to 10ft x 10ft
Oxidation (Aging)
Low AC% Mix
Absorptive Aggregates

29. Block Cracking

30. Block Cracking

31. Reflective Cracking Generally over PCC pavements
Caused by movement of the underlying layer
Vertically (Load)
Horizontally (Thermal)

32. Reflective Cracking

33. Longitudinal/Transverse Cracking
Transverse cracking is generally thermally induced
Longitudinal Cracking
paving lane joints
poor compaction

34. Longitudinal/Transverse Cracking

35. Longitudinal/Transverse Cracking

36. Longitudinal/Transverse Cracking

37. Weathering/Raveling Loss of aggregate on the surface Poor Compaction
Cold/Wet Weather Construction
Dirty Aggregate
Low AC%
Overheating Mix

38. Weathering/Raveling

39. Other Distresses Bleeding Bumps/Sags Corrugation/ Shoving Depressions
Lane/Shoulder Drop Off
Patching/Utility Cuts
Polished Aggregate
Railroad Crossings
Slippage Cracks

40. Bleeding Excessive Asphalt Low air voids Too much asphalt in mix
Too much crack sealant below overlay
Too heavy prime or tack coat?
Low air voids

41. Bleeding

42. Bleeding

43. Slippage Cracks Caused by a shear plane in the pavement structure
Too little tack
Too much tack

44. Slippage Cracks

45. Polished Aggregate

46. Distress Review

47. Primary HMA Deterioration Initial Mechanisms of Deterioration
Environment /
Aging
Material /
Mix
Load /
Traffic
Asphalt
Hardening
Various Changes
Plastic Deformation
Surface wear
The general causes of deterioration (shown on the last slide) influence pavement performance in different ways.
Traffic loadings typically lead to plastic deformation.
Traffic applications (tire/pavement interaction) cause a wearing of the surface.
Environmental and aging effects cause the oxidation (hardening) of the asphalt.
HMA material or mix problems can lead to various different types of distress.

48. Primary HMA Deterioration Load-Related Distresses
Rutting
Fatigue Cracking
Plastic
Deformation
These are build slides that show the progression of load distresses in HMA pavements.
What distresses do you see?

49. Primary HMA Deterioration Traffic-Related Distresses
Polishing
Surface Wear
An additional traffic-related distress involves the polishing of the surface which leads to friction loss. Bleeding can also lead to friction loss.
Friction Loss

50. Primary HMA Deterioration Environment/Aging-Related Distresses
Block Cracking
Raveling/Weathering
Asphalt Hardening
This is also a build slide.

51. Primary HMA Deterioration Material/Mix-Related Distresses
Material Problems
Bleeding can also lead to loss of friction.
Bleeding/Flushing
Friction Loss

52. Secondary HMA Deterioration Influence of Moisture Infiltration
Cracks +
Moisture
Infiltration
Deteriorated Cracks
Breakdown of Existing Cracks
This build slide shows the progression of deterioration from moisture infiltration.
One cause of moisture infiltration into existing cracks causes the breakdown of existing cracks. This leads to:
Increased roughness.
Allows more water to enter pavement.

53. Secondary HMA Deterioration Influence of Moisture Infiltration
Cracks +
Moisture
Infiltration
Potholes
Loss of Fines (Pumping)
Lane-to-Shoulder Drop-off
Edge Cracking
Subgrade Softening

54. Preservation Candidates
Preservation treatments must be applied when:
Pavements are in good condition
Corrective actions required on only a small area of the total pavement

55. Preservation Candidates
Pavements are not candidates for preservation:
Pavements in poor condition
Substantial repairs required
Structural deficiencies

56. Preservation Candidates
Preventive Preservation Candidates
100
Critical PCI
These Pavements are not Preservation Candidates
Pavement Condition Index
Time or Traffic

57. Review Recognize Asphalt Pavement Distresses
Know the Causes of Main Types of Distress
Determine Which Pavements are Good Candidates for Pavement Preservation

58. Questions?
Distress Identification