Characterization of Red Mud-based Curing Agent for Curing High Concentration Copper Contaminated Soil

Abstract

In order to investigate the characteristics of RCP (red mud: calcium carbide slag: cement = 3:1:1) curing agent for curing soil with high concentration of copper contamination, this paper carried out the unconfined compressive strength test, toxicity leaching test, electrical resistivity test, and scanning electron microscopy test on RCP specimens with different age of maintenance, different curing agent dosages and different initial heavy metal contamination concentrations to investigate and analyze the Unconfined compressive strength characteristics, heavy metal ion leaching concentration characteristics and resistivity characteristics of RCP cured soil under different variables.It was found that the unconfined compressive strength and resistivity of RCP cured soil increased with the increase of maintenance age and curing agent dosing, while the strength and resistivity of cured soil decreased when the initial heavy metal contamination concentration increased. The heavy metal ion leaching concentration of RCP cured soil decreased with the increase of maintenance age and curing agent dosage, while the heavy metal ion solidification rate of cured soil decreased when the initial heavy metal pollution concentration increased.By observing and analyzing the swept electron microscope images of RCP specimens maintained for 28 days, the presence of Calcovanite, hydrated calcium silicate and hydrated calcium silica-aluminate can be observed, and these hydration reaction products enhance the strength of the cured soil, as well as displace and adsorb heavy metal ions in the contaminated soil, which have a better curing effect on the heavy metal ions.