Investigation of non-standard unbound granular materials under cyclic loads: experimental and regression analyses

This study evaluated the potential use of non-standard unbound granular material (UGM) as pavement granular materials. Repeated load triaxial (RLT) tests were performed on several non-standard UGM samples to evaluate the performance as base course material for low volume traffic pavements. The laboratory test results showed that non-standard UGM samples performed better or comparable to the performance of conventional base course material in terms of permanent deformation (PD) and resilient modulus (MR). Based on these results, it would be viable to consider non-standard UGM as base course material to reduce the utilisation of conventional material and promote sustainability. In the second phase of the study, regression models for PD and MR from the literature have been evaluated to fit the laboratory test response of the non-standard UGMs. The results of the regression analyses indicated that including the bulk stresses as a prediction factor in the new developed constitutive models improved the prediction accuracy with R2 between 0.90 and 0.99. Furthermore, MEPDG model was able to successfully predict MR observed from laboratory results. Based on the results of MR regression analyses, it would be fair to state that MEPDG model can be successfully implemented in Australian pavement design method.

Automated summary

The study evaluated using non-standard UGM as pavement granular materials, found it performed well in terms of permanent deformation and resilient modulus, suggesting it could be a sustainable alternative to conventional materials. Regression models for PD and MR improved prediction accuracy, with MEPDG model successfully predicting MR for Australian pavement design method.