SAPEM Chapter 2 - Sanral

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South African Pavement Engineering Manual <strong>Chapter</strong> 2: Pavement Composition and Behaviour TABLE OF CONTENTS 1. Introduction ....................................................................................................................................... 1 2. History ................................................................................................................................................ 2 2.1 Development of Roads ................................................................................................................. 2 2.2 History of Pavement Design .......................................................................................................... 4 2.2.1 AASHO Road Test .............................................................................................................. 5 2.3 Necessity of Roads ....................................................................................................................... 6 3. Basic Principles of Roads ................................................................................................................... 8 3.1 Political Pyramid .......................................................................................................................... 8 3.2 Technical Pyramid ........................................................................................................................ 8 4. Pavement Structure ......................................................................................................................... 10 4.1 Pavement Design ....................................................................................................................... 10 5. Material Characteristics ................................................................................................................... 11 6. Pavement Types ............................................................................................................................... 14 6.1 Types of Surfacing ..................................................................................................................... 15 6.1.1 Flexible Pavements .......................................................................................................... 15 6.1.2 Rigid Pavements .............................................................................................................. 17 7. Pavement Distress ............................................................................................................................ 19 7.1 Accumulation of Distress ............................................................................................................ 20 8. Functional Performance ................................................................................................................... 22 9. Mechanics of Materials (Stresses and Strains)................................................................................ 24 9.1 Definitions of Stress and Strain ................................................................................................... 24 9.2 Normal and Shear Stresses and Strains ........................................................................................ 24 9.3 Mechanistic Pavement Analysis ................................................................................................... 26 10. Material Science ............................................................................................................................... 28 10.1 Elasticity ................................................................................................................................... 28 10.1.1 Poisson’s Ratio ................................................................................................................ 29 10.2 Plasticity ................................................................................................................................... 30 10.3 Viscosity.................................................................................................................................... 31 11. Climate .............................................................................................................................................. 33 12. Variability ......................................................................................................................................... 35 13. Life Cycle Strategy ........................................................................................................................... 36 References and Bibliography ..................................................................................................................... 38 Preliminary Section Page v
South African Pavement Engineering Manual <strong>Chapter</strong> 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
Page 1 and 2: SOUTH AFRICAN PAVEMENT ENGINEERING
Page 3 and 4: SOUTH AFRICAN PAVEMENT ENGINEERING
Page 5 and 6: South African Pavement Engineering
Page 7: South African Pavement Engineering
Page 17 and 18: Abstraction level South African Pav
Page 29 and 30: Reserve encroachment Skid resistan
Page 35 and 36: 9.3 Mechanistic Pavement Analysis S
Page 45 and 46: PAVEMENT CONDITION PAVEMENT CONDITI
Page 47: South African Pavement Engineering

SAPEM Chapter 2 - Sanral

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