Evaluation of the Compressibility and Compressive Strength of a Compacted Cement Treated Laterite Soil for Road Application

This study presents experimental results of a laboratory investigation carried out on the compressibility, physical properties, compressive strength and microstructure of a cement–lateritic soil mixing. The investigation was conducted on a compacted fine grained lateritic soil, both untreated and treated with CEMII/BM 32.5 N cement (up to 9% by weight of dry soil), in order to evaluate the effect of cement content and curing time on the behavior of lateritic soil–cement mixtures compacted at modified proctor energy for various dry densities and molding water contents. Preliminary tests on cement amended soil showed improved physical properties. The unconfined compression tests show an increase of the unconfined compressive strength, reflecting an improvement of mechanical strength of the treated lateritic soil. The incremental oedometer tests showed that yield stress (σ′_y) increased with both cement content and curing time, but decreased with increased molding water content. Reduction in modified compression index (C_cϵ) and modified recompression index (C_rϵ) with increasing cement content and curing time was recorded for all tested water contents, the coefficient of consolidation (C_v) is increased for effective vertical stresses smaller than the yield stress. The results also show that it would be desirable that the soil sample is prepared at the dry side of optimum (ω_DRY) when the optimum moisture content is not reached on the site. These positive impacts are mainly related to the fact that cement addition gives way to the formation of ettringite, calcite, portlandite and calcium silicate hydrates (afwillite and tobermorite) which derived principally from cement hydration.