Generalized strength prediction equation for cement stabilized clayey soils

Abstract

The role of clay minerals on the strength development of cement stabilized clays at different cement contents, water contents and curing times was studied in this research. Kaolin and sodium bentonite were used to represent non-swelling and high swelling soils respectively. The soils studied were mixtures of kaolin and bentonite at replacement ratios of 0, 25, 50, 75, and 100% of the dry weight of bentonite to have various swelling potentials. The water content of the soil samples was adjusted to the optimum water content (OWC) and to the liquidity index (LI) of 0.25–1.50, so as to simulate different initial soil phases. The macro- and micro-observation indicated that the clay mineral, water content and cement content were the predominant influence factors controlling the strength development of cement stabilized clays, at a particular curing time. For a particular clay mineral, the total soil water to cement content, s-w/c was found to be the prime parameter reflecting the effect from both water content and cement content on the strength development in cement stabilized clay. The generalized strength model can be represented in the form: qu = A/B(s-w/c) where qu is unconfined compression strength, and A and B are constant. The values of parameters A and B were found to be primarily controlled by the clay mineral, which was found to be described by plasticity index. The generalized strength model was validated using separated test data. This model will facilitate the engineering decision of selecting the water content and cement content to attain the target strengths of clayey soils at required curing time with minimum number of trials.