Distinguishing the effects of cementation versus density on the mechanical behavior of cement-based stabilized clays

Abstract

This paper presents a new quantitative framework that analyzes and distinguishes the two major contributors, cementation and density, on the strength generation in cement-based stabilization of a soft marine clay. Additives such as silica fume and foaming agent, were used along with conventional ordinary Portland cement (OPC) at dosages of up to 30 wt% to finely tune the cementation bonding strength and porosity respectively so that the effects of density and cementation on strength development can be separately identified and quantified. Treated soil samples cured at different times were subjected to unconfined compressive testing to obtain the stress–strain relationships, leading to the determination of compressive strength, modulus, and failure strain. Results show that the strength and modulus of the soft clay increase with the silica fume content owing to its excellent pozzolanic reaction but decrease by the foaming agent because of reduced density. Moreover, the strength and modulus are mainly dominated by cementation at a relatively low density but by density when treated with conventional OPC. A quantitative framework is then formulated to further distinguish and quantify the two strength components due to cementation and density as well as the compensation mechanisms. Moreover, the strength is more sensitive to density for soils treated by conventional cementitious additives, suggesting the important role of density control in OPC-treated soft clays.