Calcium-aluminium-silicate-hydrate (C-A-S-H) gels containing heavy metal ions (Me: Co²⁺, Cu²⁺ or Zn²⁺) were precipitated at different Me/Si molar ratios to study the uptake mechanism and immobilization capacity. Aqueous solution chemistry and solid-phase characterization using XRD, FTIR, ESEM-EDX, TEM-HAADF and TG-DSC methods reveal threshold values for ion substitution of ~55–60 mol% for Zn, ~30–40 mol% for Co and ~25–30 mol% for Cu in defective tobermorite-type C-A-S-H with (Ca + Me)/(Si + Al) molar ratios from 0.86 to 1.04. At higher aqueous Me concentrations, Me (chloride) hydroxides start to co-precipitate. The uptake mechanism of Me ions by C-A-S-H is based on (i) isomorphous substitution of Me for Ca in the CaO layer, (ii) ion exchange in the interlayer, (iii) tetrahedral substitution (Zn) within the dreierketten chains and (iv) surface adsorption onto the C-A-S-H gel structure. Systematics in crystal-chemistry of Me-bearing C-A-S-H and implications for application and performance in natural and man-made settings are discussed.

含有重金属离子（Me：Co ²⁺、Cu ²⁺或 Zn ²⁺）的钙铝硅酸盐水合物 (CASH) 凝胶) 以不同的 Me/Si 摩尔比沉淀以研究吸收机制和固定能力。使用 XRD、FTIR、ESEM-EDX、TEM-HAADF 和 TG-DSC 方法的水溶液化学和固相表征揭示了离子取代的阈值，Zn 约 55-60 mol%，Co 和约 30-40 mol%在 (Ca + Me)/(Si + Al) 摩尔比为 0.86 至 1.04 的缺陷雪硅钙石型 CASH 中，Cu 约为 25–30 mol%。在较高的 Me 水溶液浓度下，Me（氯化物）氢氧化物开始共沉淀。CASH 对 Me 离子的吸收机制基于 (i) CaO 层中 Me 对 Ca 的同晶置换，(ii) 层间的离子交换，(iii) dreierketten 链内的四面体置换 (Zn) 和 (iv)表面吸附到 CASH 凝胶结构上。