Abstract: During the improvement and reinforcement of peat foundation soils, cement hydration alters the pH of the subsurface water-soil ecosystem. This change negatively impacts humus acid, the main component of organic matter in peat soils, thereby deteriorating the engineering properties of peat foundations. Tests simulated the subsurface alkaline environment by using cement to treat peat soils in actual projects. The objective is to understand the dynamic processes of cement hydration affecting peat soil environments and to investigate the dissolution properties of humus acid in peat soil under alkaline environment during cement hydration. Results indicate that peat soil environment transforms into an alkaline environment under cement hydration, where humus acid in peat soil exhibits dissolution properties under alkaline environment. Humus acid undergoes dissolution and reacts in the alkaline environment. As the pH of the environment stabilizes, the dissolution of humus acid practically ceases. As humus acid dissolves, the pores inside peat soil expand, and the skeleton structure becomes less compact, reducing the soil’s compactness and connectedness, leading to significant strength loss. The dissolution of humus acid can significantly damage the peat soil structure. The study provides valuable insights into engineering issues arising from humus acid dissolution in peat soil under alkaline environment induced by cement hydration.

Key words: humus acid, alkaline environment, dissolution properties, soil damage, cement hydration