Pavement Design (Flexible and Rigid) - Concept Map
Pavement Design Systems
Related concepts
Flexible Pavements
Sub concepts
- Asphalt Concrete Surface
- Base Layer
- Subbase Layer
- Load Distribution Mechanism
- Rutting Failure
- Fatigue Cracking
- CBR Design Method
- Layer Thickness Design
Relationship to central
One of two primary pavement types; asphalt-based system distributing loads through layered structure
Rigid Pavements
Sub concepts
- Portland Cement Concrete Slab
- Subbase Layer
- Load Spreading by Bending
- Joint Design and Control
- Flexural Stress Analysis
- Modulus of Subgrade Reaction (k)
- Westergaard Analysis
- Slab Thickness Design
Relationship to central
One of two primary pavement types; concrete slab system using bending to carry loads
Subgrade Strength Assessment
Sub concepts
- California Bearing Ratio (CBR)
- CBR Test Procedure
- CBR Interpretation
- Modulus of Subgrade Reaction (k)
- Plate Load Test
- k-value Correlation
- Subgrade Classification
Relationship to central
Foundation capacity measurement; determines pavement thickness requirements
Traffic Loading Analysis
Sub concepts
- Equivalent Single Axle Load (ESAL)
- Load Equivalency Factor (LEF)
- Fourth-Power Law
- Axle Load Classification
- Single Axle
- Tandem Axle
- Tridem Axle
- Design ESAL Accumulation
- Traffic Growth Factors
Relationship to central
Quantifies cumulative vehicle damage; basis for design life calculations
Tire-Pavement Interaction
Sub concepts
- Tire Contact Area Calculation
- Wheel Load (P)
- Tire Inflation Pressure (p)
- Contact Stress Distribution
- Tire Type Considerations
- Dual Wheel vs Single Wheel
Relationship to central
Interface mechanics determining load transfer and contact pressure distribution
Design Formulations and Methods
Sub concepts
- AASHTO Design Guide
- CBR Method (Flexible)
- Structural Number (SN)
- NSCP 2015 Provisions
- Westergaard Theory (Rigid)
- Flexural Strength Requirements
- Design Life Selection
- Reliability and Safety Factors
Relationship to central
Mathematical frameworks and standards for pavement thickness determination
Pavement Failure Modes
Sub concepts
- Flexible Pavement Failures
- Rutting (Permanent Deformation)
- Fatigue Cracking
- Alligator Cracking
- Rigid Pavement Failures
- Flexural Cracking
- Faulting at Joints
- Corner Breaking
- Pumping
Relationship to central
Mechanisms by which pavements deteriorate under service loads
Material Properties
Sub concepts
- Asphalt Binder Properties
- Aggregate Characteristics
- Concrete Compressive Strength (f'c)
- Concrete Flexural Strength (MR)
- Base Course Material Modulus
- Subgrade Resilient Modulus (MR)
- Thermal Properties
Relationship to central
Physical and mechanical characteristics influencing design decisions
Concept connections
- Flexible PavementsCBR Design MethodCBR test determines subgrade strength, which directly controls required layer thickness for flexible pavements
- Rigid PavementsModulus of Subgrade Reaction (k)k-value is essential input for Westergaard analysis to compute flexural stresses in rigid slab
- Traffic Loading AnalysisLoad Equivalency Factor (LEF)LEF converts heterogeneous vehicle loads to standard 80 kN single axle equivalents for design ESAL calculation
- Fourth-Power LawLoad Equivalency Factor (LEF)LEF for single axles follows fourth-power relationship (W/80)^4, showing nonlinear damage accumulation
- Tire-Pavement InteractionContact Stress DistributionContact area (A = P/p) and pressure distribution affect stress patterns in pavement layers directly beneath tire
- Design ESAL AccumulationFlexible PavementsTotal accumulated ESAL over design life is input to structural number (SN) calculation for layer thickness
- Design ESAL AccumulationRigid PavementsTotal accumulated ESAL determines flexural fatigue analysis requirement and slab thickness in Westergaard design
- Rutting FailureFlexible PavementsPermanent deformation is primary failure mode in flexible pavements under repeated heavy axle loads
- Fatigue CrackingFlexible PavementsFlexural fatigue of asphalt and base layers causes alligator cracking failure in flexible pavements
- Flexural CrackingRigid PavementsTensile stresses exceed concrete flexural strength, initiating cracks perpendicular to load direction in rigid slabs
- Joint Design and ControlRigid PavementsJoints control crack location and relieve thermal stresses; critical design element in rigid pavement systems
- Westergaard AnalysisRigid PavementsWestergaard theory mathematically models slab bending and stress distribution for rigid pavement design
- Subgrade Strength AssessmentCalifornia Bearing Ratio (CBR)CBR is primary strength parameter for flexible pavement design; correlates to layer modulus
- Subgrade Strength AssessmentModulus of Subgrade Reaction (k)k-value quantifies subgrade stiffness from plate load test; essential for rigid pavement design
- NSCP 2015 ProvisionsDesign StandardsNSCP 2015 provides Philippine-specific requirements and modifications to pavement design methods
- AASHTO Design GuideDesign StandardsAASHTO is foundational design methodology adopted and adapted in Philippine and international practice
- Structural Number (SN)Flexible PavementsSN quantifies structural adequacy; product of layer thickness and material coefficients in flexible design
- Layer CoefficientsStructural Number (SN)Material-specific coefficients (a1, a2, a3) weight contributions of surface, base, and subbase to SN
- Drainage FactorsFlexible PavementsDrainage conditions and moisture affect layer moduli and long-term performance of flexible pavements
- PumpingRigid PavementsWater-induced ejection of fine subgrade material through joints; critical failure mechanism in rigid pavements
- Faulting at JointsRigid PavementsDifferential vertical displacement at joints due to erosion and consolidation; limits load transfer and rideability
- Corner BreakingRigid PavementsFatigue cracking initiating at slab corners under combined traffic and thermal stresses
- Concrete Flexural Strength (MR)Rigid PavementsModulus of rupture determines maximum allowable flexural stress in slab; critical design input
- Concrete Compressive Strength (f'c)Rigid PavementsCompressive strength correlates to flexural strength and durability; typical requirement 28–35 MPa
- Asphalt Binder PropertiesFlexible PavementsBinder grade (PG or AC) controls temperature susceptibility and fatigue resistance of asphalt layer
- Aggregate CharacteristicsMaterial PropertiesAggregate size, shape, and gradation affect friction, modulus, and workability in all pavement types
- Subgrade Resilient Modulus (MR)Material PropertiesSubgrade resilient modulus relates to CBR and affects layer stiffness inputs in flexible design
- Thermal PropertiesMaterial PropertiesTemperature-induced expansion/contraction affects joint spacing and stress in rigid; rutting in flexible
- Design Life SelectionTraffic Loading AnalysisDesign period (10, 20, 30 years) determines cumulative traffic volume and ESAL target
- Reliability and Safety FactorsDesign Formulations and MethodsDesign reliability levels (80–99%) build in safety margins against uncertainties in traffic and materials
Diagrams
Pavement Design: Complete Concept Hierarchy
Comprehensive mind map showing the hierarchical relationships of all major concepts in pavement design, organized by pavement type, design approach, and supporting analytical methods. Central node branches into eight major concept categories with progressively detailed sub-concepts.
Flexible Pavement Design Process
Step-by-step flowchart for flexible pavement design methodology, from CBR assessment through traffic loading conversion to layer thickness determination. Includes decision points for design adequacy and revision loops following AASHTO approach.
Rigid Pavement Design Process
Step-by-step flowchart for rigid pavement design methodology, from modulus of subgrade reaction (k) determination through Westergaard stress analysis to slab thickness and joint design. Includes fatigue and safety checks.
Load Equivalency Factor (LEF) Calculation Decision Tree
Decision tree for converting mixed traffic loads into equivalent single axle loads (ESAL). Shows branching logic based on axle type and demonstrates application of fourth-power law for single axles versus AASHTO table lookups for tandem and tridem axles.
Flexible vs Rigid Pavement Selection Matrix
Decision matrix flowchart for selecting between flexible and rigid pavement types based on project-specific criteria including traffic volume, subgrade strength, climate, design life, and economic factors.
Tire Contact Area Calculation Procedure
Procedural flowchart for calculating tire contact area from wheel load and inflation pressure. Emphasizes unit conversion requirements and highlights common errors in mixing unit systems.
Modulus of Subgrade Reaction (k) Determination
Flowchart showing the plate load test procedure for determining the modulus of subgrade reaction (k), from test setup through load application and deflection measurement to final k-value calculation in appropriate units.
CBR Test and Interpretation Process
Complete flowchart of the California Bearing Ratio (CBR) test procedure, from sample preparation through soaking, penetration testing, and final interpretation. Shows CBR value ranges and their implications for pavement design thickness.
Pavement Deterioration States: Flexible Pavement Life Cycle
State diagram showing the deterioration progression of flexible pavements from new condition through excellent, good, fair, and poor states to ultimate failure. Includes Pavement Condition Index (PCI) ranges and maintenance/corrective action options at each stage.
Typical Material Composition in Flexible Pavement Structure
Pie chart showing typical proportional distribution of layer thicknesses in a flexible pavement structure. Illustrates that base and subbase layers (granular materials) comprise the majority of load-bearing structure, while asphalt surface is relatively thin.