Study on Synthesis of CSH Gel and Its Immobilization of Heavy Metals

Calcium silicate hydrate (CSH) gel is the most important hydration product of cement. It influences the mechanical properties of resulting materials and plays an important role in the adsorption and immobilization of heavy metal ions. Research in the structure of CSH gel and its ability for heavy metal immobilization enables the development of tailored cement-based materials, a feature that holds significant future potential. In this study, CSH gel was synthesized under different pH and Ca/Si conditions. Structural and morphological changes in CSH gel were investigated using modern technologies. The results revealed that both pH and Ca/Si ratios were important factors influencing the structure of CSH gel. During the formation of CSH, both Cr3+ and Pb2+ can be incorporated into CSH gel, and promoting the formation of calcium hydroxide Cr3+ can also replace Si4+ in the Si-O bond.