Effects of pH and EC on the strength and permeability of plastic concrete cutoff walls

At present, plastic concrete is widely used in anti-seepage engineering, and its strength and hydraulic conductivity are important indexes of plastic concrete cutoff walls. The pondus hydrogenii (pH) and electrical conductivity (EC) have an important effect on the strength and hydraulic conductivity of plastic concrete cutoff walls. However, it is not clear why the pH and EC are related to the strength and permeability of these walls. For this reason, plastic concrete composed of sand, cement, water, and bentonite was taken as the research object to study the influence of different mix ratios and curing ages on the unconfined compressive strength and permeability of plastic concrete. The pH and EC of the corresponding mix ratio and curing age were measured. The effects of the pH and EC on the strength and permeability of plastic concrete were studied, and the internal reason was explored from the product type and hydration reaction degree of plastic concrete. Furthermore, the quantitative relationship between pH and EC and the strength and hydraulic conductivity of plastic concrete was established. With increasing cement content, the strength, pH, and EC of plastic concrete increase continuously, while the hydraulic conductivity decreases. With increasing curing age, the strength increases, the hydraulic conductivity decreases, and both the pH and EC show a trend of first increasing and then decreasing. The pH value and electrical conductivity can reflect the product type and hydration reaction degree of plastic concrete, further affecting its strength and hydraulic conductivity. Under different dosage and curing age conditions, the pH showed three stages, namely, 11.7–12.27, 12.27–2.5, and 12.5–12.75, and there is a good power functional relationship among the EC and strength and hydraulic conductivity at each stage.