1. Pavement Performance Dr. Khaled Al-Sahili
An-Najah National University Faculty of Engineering – Civil Engineering Dept Advanced Pavement Design
Pavement Performance
Dr. Khaled Al-Sahili

2. PAVEMENT FAILURE
Functional: it occurs when the pavement, due to its roughness, is unable to carry out its intended function without causing discomfort to drivers or passengers or imposing high stresses on vehicles
Structural: a collapse of the entire structure or a breakdown of one or more of the pavement components renders the pavement incapable of sustaining the loads imposed on its surface
Causes may be due to inadequate maintenance, excessive loads, climatic and environmental conditions, poor drainage leading to poor subgrade conditions, and disintegration of the component materials.
Excessive loads, excessive repetition of loads, and high tire pressures can cause either structural or functional Failure

3. Types of distresses – Flexible Pavement
Alligator or Fatigue Cracking
Block Cracking
Joint Reflection Cracking from Concrete Slab
Lane Shoulder Drop-off or Heave
Longitudinal or Transverse Cracking
Pumping or Water Bleeding
Rutting
Swell
Others – Bleeding, Corrugation, Depression, Lane-shoulder joint separation, patch deterioration, Polished Aggregates, Potholes, Ravelling, Slippage Cracking, etc.

4. Types of Distresses – Flexible Pavement

5. Cracking
Alligator Cracking: Series of interconnected cracks, many-sided, sharp-angle pieces (<1 ft. on longest side)
Severity
Possible Causes:
• Insufficient bearing support and repeated traffic loading.
• Poor base drainage.

6. Cracking
Block Cracking: Rectangular pieces of asphalt surface ranging in size from approximately 1 sq. ft. to 100 sq. ft
Related to thermal shrinkage of asphalt binder

7. Joint Reflection Cracking from Concrete Slab
Possible Causes
Movement of the rigid pavement slab beneath the HMA surface because of thermal and moisture changes. 
Generally not load initiated, however loading can hasten deterioration

8. Cracking
Edge Cracking: Crescent-shaped cracks or fairly continuous cracks, parallel to, and usually within I' to 2' of the outer edge of pavement.
Cause: when paved shoulders do not exist.
Severity Levels
Low: Cracks with no breakup or raveling.
Moderate: Cracks with some breakup or raveling.
High: Cracks with considerable breakup or raveling along edge

9. Cracking
Transverse Cracking: usually appear across the road perpendicular to the centerline.
Possible Causes:
• Poor construction joints.
• Pavement Shrinkage due to asphalt hardening or freeze/thaw cycles.
• Reflective cracking (cracks below the wearing course)

10. Patching and Potholes
Patch Deterioration: Portion of pavement surface that has been removed and replaced. Poor patching may be uneven, heavily rutted, contain different cracks, etc.
Possible Causes:
• Poorly constructed paving, thin layer of patching.
• Not sealed along seams, water intrusion defects patch

11. Patching and Potholes
Potholes: Bowl-shaped holes of various sizes in pavement surface. Potholes are localized failure areas, which may be isolated or caused by a combination of other progressively failing pavement defects (raveling, alligator cracking, patching).
Possible Causes:
• Poor quality of materials and/or construction.
• Inadequate drainage, Freeze-thaw cycling, Poor patching.

12. Deformations
Deformations in pavements can be divided in longitudinal and transverse deformations (called unevenness or roughness).

13. Deformations: Corrugations/Rutting
Longitudinal vertical surface depressions in the wheel path.
Possible Causes:
• Poorly constructed roadway.
• Substandard or failing sub-bases.
• Inadequate lateral support, failing or steep road shoulder.

14. Deformations: Shoving
Longitudinal displacement of a localized area of the pavement surface caused by traffic pushing against the pavement
Usually occur in asphalt layers that lack stability.
Lack of stability may be caused by a mixture, which is too rich in asphalt, has too high proportion of fine aggregate, or too smooth or too round aggregate

15. Deformations: Settlement
It is a dip in the longitudinal profile of the pavement surface.
Cause:
traffic heavier than design traffic (ESAL)
settlement of the lower pavement layers, or
by poor construction methods.
Severity Levels Severity is based on the effect of the settlement upon vehicle control when traveling along the road.

16. Disintegration and wear
Bleeding is a defect type that can be recognized as black, “fatty” looking spots on the pavement surface. Causes: high bitumen content or low void content

18. Disintegration and wear
Raveling is the loss of aggregate from the surface layer.
Causes: cohesive failure in the bituminous mortar or adhesive failure in the interface between aggregate and bituminous mortar
Raveling may occur as a result of poor mixture quality, segregation, or insufficient compacting

19. Lane Shoulder Drop Off
Edge drop-offs and shoulder scour are often caused by settlement, consolidation, or pumping.
Heave – freeze / thaw process

20. Water Bleeding and Pumping
Problem: Decreased skid resistance, an indication of high pavement porosity (water bleeding), decreased structural support (pumping)
Possible Causes:
Porous pavement as a result of inadequate compaction during construction or poor mix design
High water table
Poor drainage

21. Swell
Upheaval is a localized upward movement in a pavement due to swelling of the subgrade.
This can be due to expansive soils that swell due to moisture or frost heave (ice under the pavement).
FIX: Full depth patch

22. Depression
Depression is a localized area of pavement surface that is slightly lower in elevation than the surrounding pavement.
Depressions are most easily identifiable after rain when they fill with water.

23. Polished Aggregates Cause:
Soft aggregates that polish quickly under traffic
Problem: skidding

24. Slippage Cracking Cracks produce a crescent shape.
Cause: They occur when the top layer of the asphalt shears due to high deflections and a poor bond between the layers.
This type of cracking cannot be treated effectively with crack sealants

25. Concrete Pavement Blow up Longitudinal Cracks Corner Break
Faulting or Transverse Joints and Cracks
Joint Load Transfer System Associate Deterioration
Transverse and Diagonal Cracks
Lane/Shoulder Drop Off or Heave
Longitudinal Cracks
Longitudinal Joint Faulting
Pumping or Water Bleeding
Edge Punch out
Spalling
Swelling
Localized Distress
Construction Joint Deterioration
Others …

26. Corner Breaks A corner break extends through the entire slab.
Problem: Roughness, moisture infiltration, severe corner breaks will fault, spall and disintegrate
Possible Causes: Severe corner stresses caused by load repetitions combined with a loss of support, poor load transfer across the joint, curling stresses and warping stresses.

27. Faulting Or Transverse Joints and Cracks
A difference in elevation across a joint
Due to pumping

28. Spalling
Problem: Loose debris on the Pavement, roughness, generally an indicator of advanced joint/crack deterioration
Possible Causes:
Excessive stresses at the joint/crack caused by infiltration of incompressible materials and subsequent expansion (can also cause blowups).
Misalignment or corroded dowel.
Heavy traffic loading.

29. Pumping
Problem: Decreased structural support of the slab, which can lead to linear cracking, corner breaks and faulting.
Possible Causes: Water accumulation underneath the slab.

30. Joint Load Transfer System Deterioration
Indicator of a failed load transfer system
Possible Causes: Load transfer dowel bars can fail for two principal reasons:
Corrosion.
Misalignment.  

31. Longitudinal Cracking
Possible Causes:
Usually a combination of:
traffic loading,
thermal gradient curling,
moisture stresses, and
loss of support.

32. Blow Up
Rigid pavements are prone to slab buckling as a result of excessive expansion in hot weather (Figures 1 and 2)

33. Edge Punch Out
Allows moisture infiltration leading to erosion of base/subbase support, cracks will spall and disintegrate
Possible Causes:
Can indicate a localized  construction defect such as inadequate consolidation.
It can be caused by steel corrosion, inadequate amount of steel, excessively wide shrinkage cracks or excessively close shrinkage cracks.

34. Durability (D) Cracking
Series of closely spaced, crescent-shaped cracks near a joint, corner or crack. It is caused by freeze-thaw expansion of the large aggregate within the PCC slab.
Possible Causes ; Freeze-thaw susceptible aggregate.

35. Swell
Cause:
Freeze-Thaw – swelling soil

36. Transverse and Diagonal Cracking
Causes:
Repetition of Heavy Load or Stresses due to:
Temperature Gradient
Moisture Gradient
Drying Shrinkage

37. Serviceability
Serviceability is the ability of a specific section of pavement to serve traffic in its existing conditions.
One method of measurement is Present Serviceability Index (PSI) developed by AASHTO.
PSI is based on roughness and distress conditions (rutting, cracking, and patching).
Another method is to use Roughness Index

38. PSI Present Serviceability
Individual Present serviceability rating (0 to 5)
Present Serviceability Rating (PSR)
Present Serviceability Index (PSI)
Performance Index (PI) – summary of PSI over a period of time
Steps in formulating PSI

39. Objective Measurements
Mean Slope Variance (SV)
Mean Ruth Depth
Cracking (linear feet/1000 sq.ft) and Patching (square feet/1000 sq.ft)
Development of PSI Equation:
Flexible Pavement (eq. 9.14)
Rigid Pavement (eq. 9.15)

40. Roughness
It is the longitudinal profile or roughness that provides the major correlation variable for the riding comfort, an indication of PSI.
Measured by:
1. By Rod and Level
Rolling straight profilometer

41. Surface Friction
Skid Number

42. Non-Destructive Deflection Testing, NDT
Benkelman Beam Test
Dynaflect

43. Pavement Performance Expert Systems – professional judgment
Heuristic Knowledge is the subjective or private knowledge possessed by each individual, which is largely characterized by beliefs, opinions, and rules of thumb – knowledge-based systems.
Predictive Models: using equations to predict the allowable number of load repetitions when (fatigue, rutting, or low temperature) cracking occur over a certain area of pavement.

44. Introduction to Pavement Management
Problems of Highway Rehabilitation: funds are usually insufficient to adequately repair and rehabilitate every roadway section that deteriorates.
The problems is further complicated in that roads may be in poor condition but are still usable, making it easy to defer repair projects until conditions become unacceptable.
Roadway deterioration usually is not the result of poor design and construction practices but is caused by the inevitable wear and tear that occurs over a period of years.
Therefore, Pavement Management becomes necessary to balance between resources and improvement needs

45. Approaches to Pavement Management
The term pavement management is used to describe the various strategies that can be used to decide on a pavement restoration and rehabilitation policy.
The general topic of pavement management includes design, construction, maintenance, and rehabilitation.
Rehabilitation management is defined as any improvement made to an existing pavement after initial construction, excluding improvements to shoulders or bridges.
Pavement rehabilitation can be both preventive and corrective.

46. Importance of Pavement Condition Data
The first step in the process of pavement management is to secure data about the condition of each pavement section in the system.
Originally, condition data were obtained by visual inspections that established the type, extent, and severity of pavement condition.
These inspections were subjective and relied heavily on judgment and experience for determining pavement condition and program priorities.
In recent years, visual ratings have been supplemented with standardized testing equipment to measure road roughness, surface condition, pavement deflection, and skid resistance.

47. Pavement Condition Survey
Pavement condition data are used for the following purposes
1. Establishing Project Priorities
2. Establishing Options:
3. Forecasting Performance

48. Measuring Roadway Condition
(1) Pavement roughness (rideability) - PSR or PSI (2) Pavement distress (surface condition) (3) Pavement deflection (structural failure) (4) Skid resistance (safety)

49. Maintenance Requirements and Actions