COMPRESSIVE STRENGTH AND QUASI-ELASTIC MODULUS BEHAVIOURS OF A CEMENTED LATERITIC SOIL

Abstract

In Thailand, cemented soils are widely used as a base course material for construction of a flexible pavement structure. In the current design approach, the unconfined compressive strength (qu) of the cemented soil cured for 7 days is chosen as the key parameter, whereas the deformational behaviour of the pavement structure is not taken into account. On the other hand, it is known that the strains mobilised in the layers are significantly related with the design life of a pavement structure. Therefore, it is necessary to evaluate not only the qubut also the stiffness of a cemented soil. In this study, a lateritic soil was used to prepare test specimens by mixing with various cement contents (C) and cured for 7 days. Unconfined compression (UC) tests were performed to evaluate the qu and the average secant modulus (E50) as in the current design approach. In addition, triaxial compression (TC) tests, in which the specimen’s axial deformation was measured locally, were performed to reliably evaluate the quasi-elastic Young’s modulus (Eeq) at various stress states. It is found that the qu and E50 significantly increase with increasing C. The Eeq value also increases with increasing C and bulk stress (q). Dependency of Eeq on q is a kind of hypo-elastic stress state-dependent behaviour, which can be explained by the k-q model as for the resilient modulus (Mr) used in the mechanistic-empirical design of a pavement structure. The Eeq value can be mathematically expressed as a function of k, q and C.