Experimental study on the effects of multiple corrosive ion coexistence on soil-cement characteristics

Abstract

In some coastal areas, soft soils have high contents of Mg2+, Cl− and SO42−, which negatively affect the soil-cement strength when they are treated with cement. In this paper, laboratory macro- and micro-tests were carried out to study the effects of these three ions on the properties of soil-cement. First, unconfined compressive strength tests were conducted to study the effects of single ions and multiple ions on the strength of soil-cement under different curing times. Then, the soil-cement composition and the microstructure were observed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The action mechanisms of these three ions were explored through an examination of the chemical reaction process. It was found that the strength of the soil-cement decreased with an increasing ion content and that the coexistence of multiple corrosive ions had a greater effect than any single ion. When Mg2+, Cl− and SO42− coexist in soil-cement, they restrain the formation of cement hydration products, reduce the gelling property of these products and destroy the soil-cement structure, resulting in a reduction in strength. The research results provide a reference for developing a modified technique for the production of salt-rich soft soils reinforced by cement.