STUDY ON STRENGTH AND STRESS-STRAIN CHARACTERISTICS OF CHROMIUM AND CADMIUM CONTAMINATED SOIL, SOLIDIFIED BY CCR-GGBS

In recent years, to treat heavy metal contaminated soil with the industrial waste has gradually become a hot issue. In this study, the alkali-activated slag cementitious material formed by the combination of industrial waste carbide slag and slag (CCRGGBS) was used to stabilize the heavy metal chromium(Cr) and cadmium(Cd) contaminated soil. According to the unconfined compressive strength (UCS) test and scanning electron microscope (SEM) test, the effects of curing agent content and heavy metal Cr and Cd content on the strength and stress-strain characteristics of solidified soil were systematically studied. The results show that the UCS of solidified contaminated soil increases with the increase of curing agent content, and with the increase of concentrations of Cr and Cd, the strength is affected by the curing age and the amount of curing agent. When curing for a short time with a small amount of curing agent, the strength increases slightly with the increase of concentrations of Cr and Cd. When curing for a long time with a large amount of curing agent, the strength decreases with the increase of concentrations of Cr and Cd. Besides, the stress-strain curve of standard curing 28d sample shows four stages, including compaction stage, elastic deformation stage, plastic deformation stage and failure stage. On the whole, the failure strain of solidified soil is distributed between 0.7% and 1.7%, with obvious brittleness. The relationship between the compressive strength q(u) of solidified soil and the deformation modulus E-50 can be fitted by a linear function. The greater the q(u) is, the greater the E-50 is.