pH and hardness of cement-stabilized soil leachate under the influence of multiple factors

pH and hardness are crucial physicochemical properties of groundwater, exerting a substantial influence on the formation of underground ecosystems. The application of cement-stabilized soil has the potential to modify these characteristics. However, the specific impacts of cement-stabilized soil on the pH and hardness of groundwater remain poorly understood. In this study, cylindrical leaching experiments were employed to elucidate the alterations in pH and hardness of leachate derived from cement-stabilized soil under various conditions. The findings indicated that the pH of the leachate was predominantly influenced by soaking time, whereas it was minimally affected by the cement content. The dissolution of calcium hydroxide (Ca(OH)₂) resulting from hydration reactions served as the primary factor contributing to the pH fluctuations within the leachate, which ranged between 12.1 and 13.0. The proportion of cement in cement-stabilized soil directly influenced the availability of calcium ions in the leachate. Furthermore, a lower pH in the soaking solution tended to induce an elevated hardness in the resulting leachate. Of particular significance was the observation that the equivalent calcium carbonate (CaCO₃) concentration in the leachate consistently surpasses 850 mg/l. Consequently, cement-stabilized soil demonstrably exerted a substantial influence on increasing groundwater hardness. Although this contribution diminished progressively over time, it remained a non-negligible factor.