Page 11 - SAPEM-Chapter-10-2nd-edition-2014

South African Pavement Engineering Manual
Chapter 10: Pavement Design

LIST OF FIGURES
Figure 1. Effect of Traffic and Environment on Performance of Roads with Different Traffic Levels .................... 2
Figure 2. Typical Pavements ....................................................................................................................... 5
Figure 3. Stress Distribution in a Typical South African Flexible Pavement ....................................................... 5
Figure 4. Typical Stress Distribution in a Concrete Pavement ......................................................................... 6
Figure 5. Typical South African Roads for Road Categories ............................................................................ 9
Figure 6. Examples of Three Possible Design Strategies .............................................................................. 11
Figure 7. Falling Weight Deflectometer (FWD) ............................................................................................ 13
Figure 8. Stress Distribution Versus Deflections .......................................................................................... 14
Figure 9. Example Deflection Bowls ........................................................................................................... 15
Figure 10. Generalized Behaviour of Flexible Road Pavements ....................................................................... 15
Figure 11. Long-Term Changes in the Functional and Structural Indicators of Flexible Pavements ..................... 17
Figure 12. Long-Term Changes in the Elastic Response of Flexible Pavements with Lightly Cemented Layers ..... 18
Figure 13. Change in Stiffness of Different Materials with Time ...................................................................... 18
Figure 14. Long-Term Changes in Functional and Structural Indicators of Rigid Pavements .............................. 19
Figure 15. Importing Layers to Obtain Minimum Subgrade Strength ............................................................... 21
Figure 16. Southern Africa Macro-Climatic Regions Based on Thornthwaite’s Moisture Index ............................ 23
Figure 17. Example of an Axle Load Histogram ............................................................................................. 29
Figure 18. Representative Axle Load Histogram for Mixed Traffic by Equivalent Standard Axle Load Histogram .. 31
Figure 19. Damage Factors for Various Axle Configurations as a Function of Total Load ................................... 32
Figure 20. E80/Heavy Vehicle ..................................................................................................................... 34
Figure 21. Typical WIM setup ..................................................................................................................... 36
Figure 22. Potential Deviation of the ADE from the AADE .............................................................................. 38
Figure 23. Sequence of Events .................................................................................................................... 44
Figure 24. Chronological Events for Rehabilitation Design Traffic Calculations ................................................. 45
Figure 25. Effect of Counting Duration on Accuracy of Results ....................................................................... 47
Figure 26. Example Output from CTO Station ............................................................................................... 49
Figure 27. Calculation of Design Traffic........................................................................................................ 51
Figure 28. Flowchart for New Pavement Design ............................................................................................ 54
Figure 29. Concise Representation of Information from the Initial Assessment Phase ....................................... 60
Figure 30. Main Components of a Mechanistic-Empirical Pavement Design Method .......................................... 71
Figure 31. Critical Parameter and Location for Asphalt Layers ........................................................................ 76
Figure 32. Critical Parameter and Location for Granular and Waterbound Macadam Layers............................... 77
Figure 33. Relationship between Stress, Permanent Deformation (Strain) and Repetitions ................................ 79
Figure 34. Change from Lightly Cemented Layer to Equivalent Granular State ................................................. 83
Figure 35. Critical Parameters and Locations for Lightly Cemented Layers ....................................................... 83
Figure 36. Critical Parameter and Location for Selected and Subgrade Layers ................................................. 85
Figure 37. Analysis Positions for Critical Parameters ...................................................................................... 86
Figure 38. Effective Long Term Stiffness (ELTS): Example for Lightly Cemented Material ................................ 89
Figure 39. Adjustment of Subgrade Stiffness Based on Cover Thickness ......................................................... 90
Figure 40. Criteria for Determining Allowed Capacity from PN ........................................................................ 93
Figure 41. Dynamic Cone Penetrometer (DCP) ............................................................................................. 94
Figure 42. Standard Layer-Strength Diagrams for DCP Design ....................................................................... 96
Figure 43. Estimating Remaining Life Considering the Current Condition ......................................................... 96
Figure 44. Zones of a Deflection Bowl ........................................................................................................ 100
Figure 45. Using the TRRL Chart to Determine Remaining Life for a Self-Cementing Granular Base Pavement ... 103
Figure 46. Example of the TRRL Overlay Design Chart for Granular Base Pavements ...................................... 104
Figure 47. Example of Using of the AI Chart to Determine Remaining Life for a Pavement .............................. 105
Figure 48. Asphalt Institute Overlay Design Chart for Granular Base Pavements ............................................. 106
Figure 49. M10 Manual: Determine Axle Loading ........................................................................................ 112
Figure 50. Nomograph for Determining Equivalent Stiffness ......................................................................... 113
Figure 51. Relative Movement at Joint ........................................................................................................ 114
Figure 52. Nomograph for Determining Concrete Slab Thickness ................................................................... 115
Figure 53. Flowchart for Mechanistic-Empirical Design of Concrete Pavements ............................................... 116
Figure 54. Typical Catalogue Design of Concrete Block Pavements ................................................................ 121
Figure 55. Empirical Design Curves for Concrete Block Pavements ................................................................ 122
Figure 56. Concrete Block Pavement Design Curves for Road Pavements ....................................................... 123

Preliminary Sections
Page viii