lec 9_pavement design
DESCRIPTION
rajen koleyTRANSCRIPT
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
Pavements are designed based on “serviceability”
Serviceability is an indication of how good a ride the traveling public gets!
Pavement Structure
Types of Pavements
Flexible Pavements Rigid Pavements
Flexible Pavement Surfaces
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
Hot Mix Asphalt Surface
Granular Base
Natural Subgrade
Prime Coat
Typical Flexible Pavement Configuration
- Low Traffic Volume
Typical Hot Mix Asphalt Concrete (HMAC) Paving Operation
Asphalt Concrete Paving
Seal Coat Pavement (a.k.a. Chip Seal, Surface Treatment)
Surface Treatment (or Seal Coat or Chip Seal)
Granular Base
Natural Subgrade
Typical Flexible Pavement Configuration
- Low Traffic Volume
Seal Coat Construction – Asphalt Spray
Seal Coat Construction – Aggregate Spread
Seal Coat Construction – Rolling
Rigid Pavement Surfaces
Portland Cement Concrete Surface Slab
Stabilized Base
Granular Subbase
Natural Subgrade
Prime Coat
Prime Coat
Typical Rigid Pavement Configuration- High Traffic Volume
Portland Cement Concrete Surface Slab
Granular Base
Natural Subgrade
Prime Coat
Typical Rigid Pavement Configuration- Low Traffic Volume
Paving of a Concrete Pavement
Types of Rigid Pavements
Jointed Plain Concrete Pavement (JPCP)
Jointed Reinforced Concrete Pavement (JRCP)
Continuously Reinforced Concrete Pavement (CRCP)
Pre-stressed Concrete Pavements (PCP)
Types of Rigid Pavements Jointed Plain Concrete Pavement (JPCP)
Types of Rigid Pavements Jointed Reinforced Concrete Pavement (JRCP)
Types of Rigid Pavements Continuously Reinforced Concrete Pavement (CRCP)
Types of Rigid Pavements Prestressed Concrete Pavement (PCP)
Use of Aggregates in Pavement Construction
Hot Mix Asphalt Concrete (HMAC)
Portland Cement Concrete (PCC)
Granular Base and Subbase Layers
Seal Coats
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)
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)
Coarse & Fine Crystals - Igneous Rocks
Microstructure of Limestone & Marble- Sedimentary vs. Metamorphic
Excavation
Crushing
Transportation
Sizing
Stockpiling
Some Distinct AggregatesConcrete Sand
Screenings
¾” Crushed Limestone
1” Crushed Gravel
3/8” Pea Gravel
3/8” Crushed Trap Rock
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
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
Los Angeles Abrasion Test
Before
After
Soundness Test
Before After
5 Cycles of Soaking and Oven Drying
Magnesium Sulfate or Sodium Sulfate Solution
Aggregate Gradations
Continuous GapUniform
* 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
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
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100100999989897272656548483636222215159944
Aggregate Moisture States
Asphalt Concrete Mixes
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
Marshall Mix Design Method Compaction Testing
SHRP (Superpave®) Gyratory Compactor
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%)– Average the three asphalt contents above– Check 6 parameters for compliance with design criteria
Asphalt Concrete Phase Diagram
Aggregate Solids
Absorbed Asphalt
Effective(free) Asphalt
Air VoidsVAV
VEA
VAGG
VT
MAGG
MAA
MEA
MT
MTA
Distresses in Flexible Pavements
Pothole
Rutting
Alligator Cracking
Longitudinal Cracking
Transverse Cracking
Block Cracking & Edge Cracking
Flushing & Bleeding
Raveling in HMAC & Seal Coats
Failures
Airfield Pavement Failure
Airfield Pavement Failure
Distresses in Rigid Pavements
Longitudinal & Transverse Cracking
Corner Crack & Diagonal Crack
Spalling
Faulting
Punchout
Failures
Failed Crack
Shattered Slab
Pumping from Slab Edge
Polished Aggregate & Scaling
Blow-Ups (Buckling & Shattering)
Condition Assesement
PhotoLog Van
CT Photolog
Pavement Profiling
Laserand
Acceler-ometerin here
Pavement Profile
US24 Pavement Profile
WB High Freq.
The high frequency roughnessdoes not have a significantaffect on truck dynamics
US24 Pavement Profile
WB Low Freq.
Low frequency variationsare long bumps that canget trucks bouncing
US24 Pavement Profile
EB Low Freq.