PbCl2 effects on the strength and permeability of plastic concrete cutoff walls

Abstract

Plastic concrete walls are widely used in landfill and contaminated site pollution control engineering. Considering the prevalence of heavy metal lead ions contaminating the site, lead ions can affect the strength and permeability of plastic concrete walls. To this end, an experimental study on the effect of PbCl2 concentration on the strength, hydraulic conductivity and physico-chemical property indicators (pH and electrical conductivity) of plastic concrete walls composed of cement, bentonite, sand and PbCl2 solutions was carried out at different mix proportions and curing ages. The results show that the strength and pH of plastic concrete decrease with increasing PbCl2 concentration, and the hydraulic conductivity and electrical conductivity increases with increasing PbCl2 concentration at the same mix proportion and curing age. At the same PbCl2 concentration, the strength of plastic concrete increases with increasing plastic concrete cement content and curing age, and the hydraulic conductivity decreases with increasing plastic concrete cement content and curing age. Meanwhile, both pH and electrical conductivity decrease with increasing curing age, and both pH and electrical conductivity (σ) increase with increasing cement content. Consideration of pH and electrical conductivity (σ) can reflect the type of plastic concrete product and the degree of hydration reaction, which further reflects the degree of compactness and pore size of plastic concrete, thus affecting the strength and permeability of plastic concrete. Therefore, for plastic concrete with three cement contents, the strength of plastic concrete increases with increasing pH/σ, and the hydraulic conductivity decreases with increasing pH/σ at different PbCl2 concentrations and curing ages. In addition, pH/σ shows a good exponential function with plastic concrete strength and hydraulic conductivity.