Pavement
- Publication no: AP-R759-26
- ISBN: 978-1-923617-35-3
- Published: 26 March 2026
- PDF (free) Download
The purpose of this report is to propose a research strategy to investigate improved methods of testing the structural performance of unbound granular materials. This report provides a summary of the limitations of current testing methods and also identifies several alternative methods.
The project involved the undertaking of an extensive literature review of the methods used to characterise granular materials, including the performance assessment criteria to be used in pavement design and construction. This included an assessment of the viability of utilising test methods for the performance-based characterisation of granular materials and recommended areas for further investigation. Particular emphasis was placed on identifying practical tests suitable for use by road agencies.
The precision unbound granular analyser (PUMA), the Gyratory Compactor and the large wheel tracking device were identified for further evaluation.
There is a critical need for research to improve the selection of moisture conditions at which granular materials are tested and their deformation resistance compared. Offering key insights that will guide best practice, this research represents a significant contribution to research into performance testing of granular materials for the purpose of improving the fit for purpose use of granular materials.
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- 1. Introduction
- 1.1 Purpose
- 1.2 Scope
- 1.3 Methodology
- 1.4 Structure of the report
- 2. In situ Stresses Under Rolling Wheel Loads
- 2.1 Introduction
- 2.2 Behaviour of granular materials under rolling wheel loads
- 2.3 Effect of principal stress reorientation
- 2.4 Summary
- 3. Austroads Research Projects
- 3.1 Repeated load triaxial test
- 3.2 Static shear strength testing
- 3.3 Wheel tracking testing
- 4. New Zealand Research and Use of Performance Tests
- 4.1 Introduction
- 4.2 New Zealand Transport Agency performance-related specifications
- 4.2.1 Specified requirements for deformation resistance
- 4.2.2 Deformation resistance test method
- 4.3 Summary of New Zealand research and use
- 5. Australian Transport Agency Investigations and Use of Performance Tests
- 5.1 Queensland Department of Transport and Main Roads
- 5.1.1 NACOE research on standard unbound granular materials
- 5.1.2 NACOE research on non-standard/marginal granular materials
- 5.2 Transport for NSW
- 5.3 Department of Transport and Planning Victoria
- 5.4 Main Roads in Western Australia
- 5.5 Department of Infrastructure and Transport South Australia
- 5.1 Queensland Department of Transport and Main Roads
- 6. Alternative Performance-Based Tests
- 6.1 Introduction
- 6.2 European repeated load triaxial test using variable confining pressure
- 6.3 University of Illinois modified repeated load triaxial test
- 6.4 PUMA
- 6.4.1 Test description
- 6.4.2 Comments on modulus results
- 6.4.3 Comments on permanent deformation results
- 6.5 Shear stress during gyratory compaction
- 6.6 Alternative wheel tracking tests
- 7. Performance Test Proposed Way Forward
- 7.1 Introduction
- 7.2 PUMA evaluation
- 7.3 Large wheel tracking test evaluation
- 7.4 Gyratory shear stress
- 8. Granular Test Moisture Contents
- 8.1 Current methods of selecting test moisture content
- 8.2 Need to select mix-specific test moisture content
- 8.3 Austroads research considerations
- 9. Austroads Guide Deformation Modelling Considerations
- 9.1 Introduction
- 9.2 Austroads method for predicting the performance of flexible pavements
- 9.3 International prediction methods
- 9.3.1 United States of America
- 9.3.2 United Kingdom
- 9.3.3 South Africa
- 9.4 SPARC prediction model
- 9.5 Future modelling developments
- 10. Conclusions
- References