Assessment Of Groundwater Contamination Potential From Cement-Stabilized Soils Under Varying Ph And Moisture Conditions

Soil cement stabilization is a landmark of geo-environmental engineering in an era of increased acid rain events and variable groundwater regimes; nevertheless, whether or not it will be resistant to chemically hostile environments over time is a matter of controversy. The research provides an all-encompassing mechanistic model of leachate-induced degradation of cement-treated soils in acidic (pH 4), neutral (pH 7), and alkaline (pH 10) soils at different moisture conditions. The coupled evolution of the contaminant mobility, the strength of the matrix, and the mineralogy was followed by integrated hydro-chemical, mechanical, and microstructural analyses. The findings indicate that acidic exposure enhances the rate of C–S–H decalcification, mobilizes Pb²⁺, Zn²⁺, and Cd²⁺ up to 2.6-3.4 times higher than under neutral conditions, and cyclic wetting augments permeability by 47% and decreases unconfined compressive strength by 23%, intensifying advective transport. The presence of XRD-FTIR materials that proved the secondary formation of carbonate and ettringite dissolution was in agreement with thermodynamic forecasts. Quantitative application of laboratory leaching to field-scale contaminant migration was achieved by kinetic modeling with the Freundlich and first-order equations (R² ≥ 0.96), and subsequent HYDRUS-1D transport simulations, by matching field-scale breakthrough concentrations with a margin of error of±8 %. The suggested Global Contamination Index (GCI) that combines Cf, I geo, and HI found the pH four cyclic scenario alone as a scenario that violated the safety limit (GCI > 1).