Resilient modulus of hydrated cement treated crushed rock base (HCTCRB) for road base material in Western Australia

Abstract

Hydrated Cement Treated Crushed Rock Base (HCTCRB) is a modified base course material, with anadditional of 2% Portland cement (by mass) to a standard crushed rock base. Based on the HCTCRB application protocol, the mix is retreated after hydration to avoid producing the base course material as a bound material. HCTCRB has been usually implemented to the Western Australian road networks based on empirical design and application with experiences. Accordingly, the material characterisation of HCTCRB in accordance with the pavement mechanistic approach is strongly required to understand its behaviours and performances under the service stage. This paper aims to present the mechanical behaviour of HCTCRB resulting from the repeated load triaxial tests. Testing results of HCTCRB in terms of resilient modulus (MR) were investigated and compared to that of standard crushed rock. It wasfound that HCTCRB technique greatly improved the performance of the parent materials about triple. The results also indicated that the hydration periods significantly affected the performances of HCTCRB. CRB and HCTCRB samples exhibited the stress dependences. Generally, the deviator and confining stresses considerable affected the resilient responses of the materials as the increase of the applied stresses resulted in the higher MR values but lower incremental rates of MR. At constant confining pressure, the MR increased with increasing deviator stresses. However, the incremental rates decreased at higher levels of confinements. Similarly, at constant deviator stress, the MR climbed upwith higher confining stresses and the rates of increase were less pronounced at higher deviator stress levels. Several constitutive models for determining the MR were examined based on the laboratory results. These evaluations suggest that the K-model is still useful for modelling of these materials due to its simplicity and high degree of determination.