Strength prediction of cement-stabilised reclaimed asphalt pavement and lateritic soil blends

In this research, marginal lateritic soil (LS) was used for improving the gradation properties of reclaimed asphalt pavement (RAP) prior to cement stabilisation for heavy and light-volume roads. The unconfined compressive strength (q(u)) of cement-stabilised RAP-marginal LS blends was found to increase with LS replacement due to the improvement of gradation properties and lower asphalt binder content. The soil-water/cement ratio (w/C) was successfully implemented for a particular RAP:LS ratio to integrate the effects of water and cement contents on strength development at the optimum water content and on the wet side of optimum. By incorporating a new parameter termed as the asphalt binder content (AS), a general strength relation equation was proposed for various water contents, cement contents and RAP:LS ratios. The general strength relation of cement-stabilised RAP-marginal LS blends is presented based on three critical material constants, which are A*, B* and k. The A* and B* constants mainly depends on curing time, while the k constant is essentially the same. The general strength relation was furthermore validated with measured strength data. The general strength relation is useful as a mix design tool for determining the optimal input of cement for various RAP:LS ratios to meet strength requirement for base and subbase applications. A mix design method with a minimum trial test is furthermore proposed in this paper.