Engineers Australia

A three dimensional model for the evaluation of resilient modulus of unbound granular materials

Bao Thach Nguyen and Abbas Mohajerani


Resilient modulus is an important property that controls the performance of the subgrade and granular materials under repeated loading and is required for mechanistic-empirical pavement design. Technically, resilient modulus can be obtained from the repeated load triaxial test in the laboratory. Due to the time-consuming, complicated and expensive nature of the test, it is common to estimate the resilient modulus from other simpler approaches. Due to the discontinuous nature of the unbound granular materials, discrete element method has been used recently to predict resilient modulus for granular materials. It is clearly necessary that the proposed model be verified by comparing with the experimental results and there appears to be no validation against the experimental resilient modulus for these reported models. In this study, the laboratory repeated load triaxial test was carried out for one of the popular pavement materials used in Victoria, 20 mm class 1 crushed rock. The resilient modulus results were then compared with the result from the model. By restricting the rotational motion to simulate the interlocking effect of the particles, it was observed that the resilient behaviour from the model and the experimental test is almost identical.