Asphalt Laboratory Fatigue Relationships

The Austroads mechanistic-empirical design system documented in Part 2 of the Guide to Pavement Technology uses a laboratory fatigue relationship previously developed by Shell to predict the fatigue life of asphalt layers. The Shell fatigue relationship was developed over 40 years ago based on testing a selection of asphalt mixes from Europe and the USA. The mixes used to develop the original relationship are therefore unlikely to represent the modulus and fatigue behaviour of modern mixes (including mixes incorporating recycled materials) currently being used in Australia and New Zealand.

Austroads project Asphalt Laboratory Fatigue Relationship – Stage 1 Utilisation of Existing Data benchmarked available fatigue laboratory test results of locally manufactured asphalt mixes against the fatigue performance predicted by the generic Austroads fatigue relationship. The project also reviewed some important modulus and fatigue testing parameters that may affect the design of asphalt layers, including different sample preparation methods and the minimum number of test specimens required to develop a laboratory fatigue relationship.

This webinar with Joe Grobler, Dr Negin Zhalehjoo and Peter Bryant, presents the findings of the project, including the preliminary fatigue relationships developed for locally manufactured asphalt mixes with conventional (unmodified) bitumen.