Experimental investigation of the compressibility behaviour of cement-solidified/stabilised zinc-contaminated kaolin clay

Heavy metal contamination has become a major environmental pollution issue in China, especially under the process of rapid urbanisation. Zinc contaminants are reported to be especially harmful for local ecosystems and biodiversity. In this study, a cement-based solidification/stabilisation technique was adopted to remediate zinc-contaminated kaolin clay and a series of one-dimensional oedometer tests was performed to investigate the compressibility of cement-stabilised zinc-contaminated soils. Compression curves were analysed using a simulation of the logistic function, and the yield stress (σ'vp), swelling index (Cs) at the pre-yield state and compression index (Cc) at the post-yield state were derived on the basis of the mathematical simulation. The effects of zinc concentration on σ'vp, Cs and Cc are discussed. It is found that relatively high zinc concentrations (i.e. >0.1%) significantly influence the compression parameters and hence deteriorate the resistance to compression of the stabilised soils. The reduction in resistance to compression at high zinc concentrations is intrinsically attributed to the destruction of cementation structure/bonding in the stabilised soils. Physicochemically, this is attributed to the retardation effect of zinc contaminants on cement hydration processes