Redesigning the Austroads creep procedure for the evaluation of permanent deformation of asphalt pavements in Australia

Redesigning the Austroads creep procedure for the evaluation of permanent deformation of asphalt pavements in Australia

The broad spectrum of dynamic creep tests developed over the last decade around the world is one of the more significant innovations in the prediction and analysis of the behaviour of asphalt pavements. Although current laboratory creep test methods have good potential for evaluating permanent plastic deformation of asphalt mixtures, there are serious concerns about their abilities to provide any precise prediction of asphalt susceptibility to permanent plastic deformation. These concerns have arisen when creep test outcomes have been unsuccessfully compared with data from field assessments.

In response to the critical questions about the adequacy of the various unconfined creep tests to predict permanent plastic deformation of asphalt, many researchers have been attempting to develop methods to improve laboratory test methods. It has been hypothesised that by providing a lateral pressure around the laboratory specimens, it would be possible to better simulate field conditions and obtain more relevant creep test outcomes.

In this study, a new methodology is explored to provide effective confinement for asphalt creep specimens. The proposed methodology is founded on the current Australian test, adapted to provide simulated field conditions. Finite Element Method (FEM) modelling is employed in the study to provide a formative view about the overall study. It is used to develop a correlation between the new confined test and in situ pavement conditions.

It has been established that the new confined dynamic creep test method (CDCT) is a superior test for duplicating in-situ conditions than the existing test methods. Outcomes of the study indicate that the CDCT will significantly decrease existing shortcomings associated with the existing Australian creep test. It is concluded that the CDCT is a much improved test method that better represents in-situ conditions and it can be used as a methodology for evaluating permanent deformation of asphaltic pavements.