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Improved Laboratory Characterisation of the Deformation Properties of Granular Materials

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Publication no: AP-T324-17 Pages: 129
Published: 08 August 2017


This report examines the capacity of the extra-large wheel-tracking laboratory test method to predict the in-service performance of granular materials.

Rutting is a common distress mode of unbound granular bases under thin bituminous surfacings.

Five granular bases were tested for rut-resistance under accelerated loading and the results compared to a number of laboratory characterisation tests. The laboratory tests included large-scale wheel tracking, repeat load triaxial and shear strength.

It was concluded that the large-scale wheel-tracking test was the best available test to rank granular base rut-resistance. It is a useful performance-based test, which can lead to significant cost saving by optimising the use of otherwise non-traditional locally available aggregate resources.


Table of Contents

Summary
1. Introduction
  • 1.1 Background
  • 1.2 Project Objective and Outline
  • 1.3 Report Outline
2. Findings of Previous Wheel-tracking and RLT Testing Research
  • 2.1 Introduction
  • 2.2 Austroads RLT Findings
  • 2.3 Findings of Wheel-tracking Testing
3. Properties of Materials Selected for Evaluation
  • 3.1 General
  • 3.2 Results of Basic Characterisation Testing
4. Full-scale Accelerated Loading Program
  • 4.1 Introduction
  • 4.2 Pavement Composition
  • 4.3 Loading Conditions
  • 4.4 Test Pavement Layout
  • 4.5 Experiments
  • 4.6 As-constructed Pavement Conditions
  • 4.7 Moisture Control and Management
  • 4.7.1 Increase in Moisture Content
  • 4.8 Pavement Condition Data
  • 4.8.1 Surface Deflection
  • 4.8.2 Moisture Content
  • 4.8.3 Dry Density
  • 4.8.4 Surface Deformation
5. Performance During Accelerated Loading
  • 5.1 Introduction
  • 5.2 Uniformity of Test Sections
  • 5.3 Analysis of Deformation Data
  • 5.3.1 Adjustment for Bedding-in
  • 5.3.2 Prediction Model
  • 5.3.3 Results
  • 5.4 Effect of Moisture Content on Performance
  • 5.4.1 Deformation-moisture Prediction Models
  • 5.4.2 Comparison of Performance (10 mm Deformation)
  • 5.4.3 Comparison of Performance (Deformation after 200 000 Passes)
  • 5.5 Summary
6. Evaluation of Laboratory Wheel-Tracking Test
  • 6.1 Introduction
  • 6.2 Summary of the Wheel-tracking Method
  • 6.2.1 Terminology
  • 6.2.2 Specimen Preparation
  • 6.2.3 Test Method
  • 6.2.4 Achieved Specimen Properties
  • 6.3 Performance Parameters and Analysis
  • 6.3.1 Laboratory Wheel-tracking Performance Analysis
  • 6.3.2 Wheel-tracking Deformation Model
  • 6.4 Results of Laboratory Wheel-tracking Testing
  • 6.4.1 Testing Program
  • 6.4.2 Wheel-tracking Results
  • 6.5 Effect of Moisture on Deformation Under Wheel Tracking
  • 6.5.1 Moisture Sensitivity Model
  • 6.5.2 Influence of Measured Density on Performance
  • 6.5.3 Comparison of Material Performance
  • 6.5.4 Comparison of Surface Deformation for Given Number of Cycles
  • 6.5.5 Effect of Degree of Saturation
  • 6.6 Performance Ranking from the Wheel-tracking Test Compared to Accelerated Loading
7. Evaluation of Austroads Repeated Load Triaxial (RLT) Test
  • 7.1 Introduction
  • 7.2 Testing Conditions
  • 7.3 Test Densities and Moisture Contents
  • 7.4 Results
  • 7.5 Effect of Moisture Content on Permanent Deformation
  • 7.6 Ranking of Performance
  • 7.7 Comparison of Ranking from Austroads RLT Test and Accelerated Loading
8. Evaluation of the TMR Repeated Load Triaxial Test
  • 8.1 Test Method
  • 8.2 Test Densities and Moisture Contents
  • 8.3 Results
  • 8.4 Ranking of Performance: TMR RLT Test Compared to Accelerated Loading
9. Evaluation of Static Shear Strength Test
  • 9.1 Introduction
  • 9.2 Pavement Stress Analysis
  • 9.3 Test Method
  • 9.4 Results
  • 9.5 Effect of Moisture Content on Performance
  • 9.6 Comparison of Shear Strength Results with Performance under Accelerated Loading
10. Conclusions
References
Appendix A Summary of Data Obtained in Accelerated Loading Experiments
Appendix B Deformation Prediction Models Calculated from Accelerated Loading Data
Appendix C Moisture Sensitivity Models Fitted to Accelerated Loading Data
Appendix D Laboratory Wheel-tracking Density Data
Appendix E Laboratory Wheel-Track Deformation Prediction Model
Appendix F Laboratory Wheel-tracking Performance
  • F.1 Cycles to 10 mm Deformation
  • F.2 Effect of Deformation Level on Performance Ranking
  • F.3 Moisture Sensitivity Including Extra Data
  • F.4 Level of Deformation at Different Cycle Numbers
  • F.5 Performance Ranking Based on Rut Depth
Appendix G TMR Repeat Load Triaxial Testing
  • G.1 Introduction
  • G.2 Summary of TMR Test Method
  • G.3 Maximum Dry Density and Optimum Moisture Content
  • G.4 Results of RLT testing
  • G.4.1 Test Densities and Moisture Contents
  • G.5 Permanent Deformation Results
Appendix H Shear Strength Testing Results

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