Test Study on Solidification of Copper Contaminated Soil by Alkali Activated Cementitious Materials

The potential use of two industrial waste by-products, namely, fly ash(FA) and ground granulated blast furnace slag(GGBS),as alternative green binders in solidification of copper contaminated soil is presented.To investigate the effectiveness of the solidification of copper contaminated soil amended by FA,GGBS and FA-GGBS activated with Ca(OH)₂,NaOH,The unconfined compressive strength test, copper leaching and scanning electron microscopy(SEM) imaging tests are conducted.The results show that FA,GGBS and FA-GGBS can improve the compressive strength of copper contaminated soil.The compressive strength of copper contaminated soil amended by FA-GGBS is higher than that of FA and GGBS alone, which can be increased by about 30%.The hydration reaction of FA-GGBS activated with NaOH is slower than that activated with Ca(OH)₂.When the curing time is 28 days, NaOH can be used to activate FA-GGBS to solidify copper contaminated soil, When the curing time is 7 days, Ca(OH)₂ can be used.The leaching performance of Cu²⁺ in soil under acid solution leaching is related to the dosage of FA-GGBS and the curing time of contaminated soil.with the increase of dosage and curing time, the leached Cu²⁺ concentration decreases significantly.Aalkali-activated cementitious material has a good stabilization effect on copper contaminated soil.SEM test results show that with the increase of Cu²⁺ concentration, the porosity of copper contaminated soil increase gradually, resulting in the decrease of strength and stabilization effect.The study provides a feasible method for the solidification and restoration of copper contaminated soil.