SAPEM Chapter 2 - Sanral

South African Pavement Engineering Manual
Chapter 2: Pavement Composition and Behaviour
LIST OF TABLES
Table 1. Classification of Pavements Based on Application and Traffic ......................................................... 14
Table 2. Road User Needs, Functional Parameters and Behaviour Measurements ......................................... 22
Table 3. Typical Poisson Ratio Values ....................................................................................................... 30
LIST OF FIGURES
Figure 1. Typical Roman Pavement (McCauley, 1974) ................................................................................... 2
Figure 2. Pavement Structure ..................................................................................................................... 3
Figure 3. Bain’s Kloof Pass .......................................................................................................................... 4
Figure 4. Conceptual Impact of Technological Developments on Roads ........................................................... 4
Figure 5. Impassable Unsurfaced Roads Due to Wet Conditions, Early 20 th Century ......................................... 5
Figure 6. AASHO Road Test (AASHTO, 1961) ............................................................................................... 6
Figure 7. Road Concepts Political and Technical Pyramids for Roads ............................................................... 8
Figure 8. Typical Pavement Structures ....................................................................................................... 10
Figure 9. Example Cross-sections of the Typical Pavement Materials ............................................................ 12
Figure 10. Expected Behaviour of Material Types as a Function of Bitumen and Active Filler Content ................. 13
Figure 11. Classification of Pavement Types based on Materials ..................................................................... 14
Figure 12. Schematic Illustration of Seal Types (a) ....................................................................................... 16
Figure 12. Schematic Illustrations of Seal Types (b) ...................................................................................... 17
Figure 13. Schematic Illustrations of the Types of Rigid Pavements ................................................................ 18
Figure 14. Evolution of Failure Mechanisms with Time and Loading ................................................................ 20
Figure 15. Structural Performance Incorporated into Pavement Condition ....................................................... 21
Figure 16. Pumping of Stabilised Base ......................................................................................................... 22
Figure 17. Surface Cracking and Potholing ................................................................................................... 23
Figure 18. Functional Performance for Different Road Structures ................................................................... 23
Figure 19. Force Applied to an Element of Material ....................................................................................... 24
Figure 20. Normal Stresses ......................................................................................................................... 25
Figure 21. Volume and Shape Changes ........................................................................................................ 25
Figure 22. Principal Stresses ....................................................................................................................... 25
Figure 23. Conceptual Bending Model for a Bound Layer on Unbound Support ................................................ 27
Figure 24. Conceptual Model of Stress-Distribution for Unbound Layer on Unbound Support ............................ 27
Figure 25. Elastic Response to a Load, Sustain, Unload Cycle ........................................................................ 28
Figure 26. Elastic Modulus as a Function of Stress and Strain ........................................................................ 29
Figure 27. Poisson’s Ratio () ..................................................................................................................... 29
Figure 28. Plastic Response to a Load, Sustain, Unload Cycle ........................................................................ 30
Figure 29. Elasto-plastic Behaviour and Resilient Modulus ............................................................................. 31
Figure 30. Viscous Response to a Load, Sustain, Unload Cycle ....................................................................... 32
Figure 31. Thornthwaite’s Moisture Index for Southern Africa ........................................................................ 33
Figure 32. Minimum Asphalt Design Temperature on Surface ........................................................................ 34
Figure 33. Maximum Asphalt Design Temperature at 20 mm Below Surface .................................................... 34
Figure 34. Pavement Deterioration with a Heavy Rehabilitation Strategy ......................................................... 36
Figure 35. Pavement Deterioration with a Frequent Maintenance Strategy ...................................................... 36
Figure 36. Impact of Timeous Maintenance on Life Cycle Costs...................................................................... 37
Preliminary Section
Page vi