硅酸三钙在含氯离子或镁离子溶液中的溶解动力学行为

Dissolution Kinetics of Tricalcium Silicate in Solution Containing Chloride or Magnesium Ions

研究了海水中典型的氯离子和镁离子对水泥熟料主要矿物硅酸三钙(C_(3)S)早期溶解行为的影响。通过自制的溶解平台和电感耦合等离子体发射光谱仪技术,获得了不同浓度的氯离子和镁离子溶液中C_(3)S的溶解速率,并利用恒温量热仪表征了氯离子和镁离子对C_(3)S溶解放热的影响,再结合扫描电子显微镜对C_(3)S块体在溶解过程中的表面形貌进行了分析。结果表明:在低离子强度下,氯离子和镁离子均会抑制C_(3)S的溶解,镁离子的抑制效果更明显;在高离子强度下,氯化钠和氯化镁转为促进C_(3)S溶解。由于大量的钠离子和镁离子的强溶剂化作用,削弱了C_(3)S晶体中钙离子的溶剂化程度,使钙离子溶剂化壳中的水分子稳定度下降,大量存在的背景离子又加速了晶体附近的水分子迁移,进而促进了钙离子的溶出。

Effect of chloride and magnesium ions in seawater on the early dissolution of the major clinker in cement(i.e.,tricalcium silicate,C_(3)S)was investigated.The dissolution rates of tricalcium silicate in solutions containing chloride and/or magnesium ions at various concentrations were obtained through lab-made platform and inductively coupled plasma-optical emission spectroscopy.The influence of chloride and magnesium ions on the dissolution heat release of tricalcium silicate was investigated by isothermal calorimetry.The morphology of tricalcium silicate tablet during the dissolution process was determined by scanning electron microscopy.The results show that,chloride ion and magnesium ions both inhibit the dissolution of tricalcium silicate and the inhibiting effect of magnesium ion is more pronounced at a low ionic strength.Sodium chloride and magnesium chloride promote the dissolution of tricalcium silicate at a high ionic strength.The intense solvation of vast sodium and magnesium ions weakens the solvation effect of chloride ion in tricalcium silicate crystal and reduces the stability of water molecules in the solvation shell of chloride ion.Moreover,the presence of massive background ions accelerates the migration of water molecules in the vicinity of the crystal surface,thus promoting the dissolution of chloride ion.