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Lec 9_Pavement Design.ppt
- 1. Pavement Engineering What is a Pavement? A structure built on existing ground to facilitate rapid, safe, reliable & comfortable traffic movement Pavement engineering involve the study of: • Pavement Materials • Pavement Structural Analysis • Pavement Design • Pavement Maintenance and Rehabilitation • Pavement Management Systems
- 2. Pavements are designed based on “serviceability” Serviceability is an indication of how good a ride the traveling public gets!
- 4. Types of Pavements Flexible Pavements Rigid Pavements
- 6. Hot Mix Asphalt Surface Hot Mix Asphalt Binder Course Stabilized Base Granular Subbase Natural Subgrade Prime Coat Prime Coat Tack Coat Typical Flexible Pavement Configuration - High Traffic Volume
- 7. Hot Mix Asphalt Surface Granular Base Natural Subgrade Prime Coat Typical Flexible Pavement Configuration - Low Traffic Volume
- 8. Typical Hot Mix Asphalt Concrete (HMAC) Paving Operation
- 10. Seal Coat Pavement (a.k.a. Chip Seal, Surface Treatment)
- 11. Surface Treatment (or Seal Coat or Chip Seal) Granular Base Natural Subgrade Typical Flexible Pavement Configuration - Low Traffic Volume
- 12. Seal Coat Construction – Asphalt Spray
- 13. Seal Coat Construction – Aggregate Spread
- 14. Seal Coat Construction – Rolling
- 16. Portland Cement Concrete Surface Slab Stabilized Base Granular Subbase Natural Subgrade Prime Coat Prime Coat Typical Rigid Pavement Configuration - High Traffic Volume
- 17. Portland Cement Concrete Surface Slab Granular Base Natural Subgrade Prime Coat Typical Rigid Pavement Configuration - Low Traffic Volume
- 18. Paving of a Concrete Pavement
- 19. Types of Rigid Pavements Jointed Plain Concrete Pavement (JPCP) Jointed Reinforced Concrete Pavement (JRCP) Continuously Reinforced Concrete Pavement (CRCP) Pre-stressed Concrete Pavements (PCP)
- 20. Types of Rigid Pavements Jointed Plain Concrete Pavement (JPCP)
- 21. Types of Rigid Pavements Jointed Reinforced Concrete Pavement (JRCP)
- 22. Types of Rigid Pavements Continuously Reinforced Concrete Pavement (CRCP)
- 23. Types of Rigid Pavements Prestressed Concrete Pavement (PCP)
- 24. Use of Aggregates in Pavement Construction Hot Mix Asphalt Concrete (HMAC) Portland Cement Concrete (PCC) Granular Base and Subbase Layers Seal Coats
- 25. Classification of Aggregates Based on Origin (Natural & Artificial) Based on Density of Particles – Normal Weight (SG 2.5-2.8); Lightweight (SG 1.5-2.0) Based on Method of Processing (Crushed/uncrushed) Based on Affinity to Water – Hydrophilic (siliceous); Hydrophobic (Carbonaceous) Based on Particle Size – Coarse Aggregate (Larger than #4 sieve) – Fine Aggregate: #4(4.75mm) to #200 sieves (75 m) – Mineral filler (finer than #200 sieve)
- 26. Natural & Artificial Aggregate Types Natural aggregates from: Igneous Rocks (Granite) Metamorphic Rocks (Marble, Gneiss, Quartzite) Sedimentary Rocks (Limestone, Dolomite, Sandstone, Caliche) Artificial aggregates from: Byproducts of Industrial Processes (Blast-furnace slag; Iron-ore gravel) Manufactured Aggregates (Lightweight aggregate, Hydrated fly ash)
- 27. Coarse & Fine Crystals - Igneous Rocks
- 28. Microstructure of Limestone & Marble - Sedimentary vs. Metamorphic
- 29. Excavation
- 30. Crushing
- 31. Transportation
- 33. Some Distinct Aggregates Concrete Sand Screenings ¾” Crushed Limestone 1” Crushed Gravel 3/8” Pea Gravel 3/8” Crushed Trap Rock
- 34. Criteria for Selection of Aggregates Stabilized (Bound) Materials Compatibility with binder Durability -Resistance to freeze-thaw, degradation Stability (or strength) of the Mix Unstabilized Materials Strength Durability Drainability Low frost susceptibility
- 35. Important Aggregate Properties Gradation (ASTM C-33) Specific Gravity & Absorption (ASTM C-127, C-128) Hardness or Resistance to Wear (ASTM C-131) Durability (Resistance to wet-dry, freeze-thaw, heat-cool) Shape and Surface Texture Deleterious Substances (ASTM C-40, C-142) Surface Chemistry Particle Crushing Strength Standard Tests by ASTM, AASHTO, State DOTs
- 36. Los Angeles Abrasion Test Before After
- 37. Soundness Test Before After 5 Cycles of Soaking and Oven Drying Magnesium Sulfate or Sodium Sulfate Solution
- 39. * Uniformly graded - Few points of contact - Poor interlock (shape dependent) - High permeability * Well graded - Good interlock - Low permeability * Gap graded - Only limited sizes - Good interlock - Low permeability Types of Gradations
- 40. Aggregate Size Definitions Nominal Maximum Aggregate Size – one size larger than the first sieve to retain more than 10% Maximum Aggregate Size – one size larger than nominal maximum size 100 100 90 72 65 48 36 22 15 9 4 100 99 89 72 65 48 36 22 15 9 4
- 43. Asphalt Concrete 3-phase system (aggregate, asphalt cement, air) Mix design to achieve maximum stability – Aggregate type & gradation – Asphalt content (% by weight of total mix) – % Air voids Mix design methods – Marshall Method – Hveem Method – Superpave Method
- 46. Design Parameters Six Mix Design Parameters – Stability – Flow – Unit weight of compacted mix – Voids in mineral aggregate (VMA) – Percent voids in mix – Voids filled with asphalt (VFA) Mix Design Method – Calculate asphalt content for maximum stability, maximum unit weight and median air voids (4%)
- 47. Asphalt Concrete Phase Diagram Aggregate Solids Absorbed Asphalt Effective(free) Asphalt Air Voids VAV VEA VAGG VT MAGG MAA MEA MT MTA
- 48. Distresses in Flexible Pavements
- 49. Pothole
- 50. Rutting
- 54. Block Cracking & Edge Cracking
- 56. Raveling in HMAC & Seal Coats
- 57. Failures
- 60. Distresses in Rigid Pavements
- 61. Longitudinal & Transverse Cracking
- 62. Corner Crack & Diagonal Crack
- 63. Spalling
- 64. Faulting
- 65. Punchout
- 66. Failures
- 67. Failed Crack
- 68. Shattered Slab
- 69. Pumping from Slab Edge
- 70. Polished Aggregate & Scaling
- 71. Blow-Ups (Buckling & Shattering)
- 74. PhotoLog Van
- 75. CT Photolog
- 77. Pavement Profile
- 78. US24 Pavement Profile WB High Freq. The high frequency roughness does not have a significant affect on truck dynamics
- 79. US24 Pavement Profile WB Low Freq. Low frequency variations are long bumps that can get trucks bouncing
- 80. US24 Pavement Profile EB Low Freq.
Editor's Notes
- Some aggregate sources are obtained by removing materials from the bottom of lakes and rivers.
- The first step in preparing stockpiles for specific uses is the crushing the larger boulders and aggregates into usable sizes.
- Once materials are obtained,they are usually transported by land, rail, or barge to a centrally located plant for separation into specific sizes.
- Once the rock has been sufficiently reduced in size, it is separated into individual stockpiles with specific ranges of particle sizes. Large screening operations have a number of wire mesh screen decks with each deck having progressively smaller openings between the wires. These screens are slanted and empty the material retained on each screen out onto conveyor belts. These belts then move the material into individual stockpiles of a particular size.
- Damage to the aggregate after a number of wet-dry cycles can be seen by visual examination as well as in the change in gradation.
- There are several general types of aggregate gradations. Uniform gradations have large percentages of one size. Well graded aggregates have approximately equal amounts on each sieve in the stack. Gap graded aggregates have large and small but few intermediate sizes. The properties of the aggregate gradation depends strongly on the distribution of aggregates sizes.
- For HMA pavements these are the definitions for gradations.