铝酸三钙水化浆体固化氯离子能力研究

Chloride Binding Capacity of Hydrated C3A Pastes

采用平衡法研究了氯离子浓度、氯盐溶液pH值和钙离子对铝酸三钙(C3A)水化浆体固化氯离子的能力及其固化产物的影响.结果表明:C3A水化生成的水化铝酸三钙(C3AH6)能够固化氯离子,其在碱性溶液中与氯离子反应生成的Friedels盐(Fs)与水铝钙石(OH-AFm)之间的固溶体有2种类型,结构分别与β-Fs-R(高温三方晶系的Fs)和α-Fs-M(低温单斜晶系的Fs)类似,氯盐溶液的pH值会影响生成固溶体的类型;随着氯离子浓度的提高,C3A水化浆体中固溶体生成量和氯离子固化量增大,平衡后氯盐溶液pH值提高,但固化氯离子占总氯离子的比例降低;氯盐溶液pH值降低导致C3A水化浆体中固溶体生成量减少,氯离子固化能力减弱;钙离子减少了固溶体的生成量,降低了氯盐溶液pH值,但提高了C3A水化浆体的氯离子固化能力.

Chloride binding capacity of hydrated C 3A pastes exposed to chloride solutions was investigated based on equilibrium method and the influences of chloride concentration,pH value and Ca^ 2+ of exposure solutions were studied. The results show the product from C 3A hydration,tricalcium aluminate hexahydrate(C 3AH 6),can bind chloride in alkaline solution to yield two types of solid solutions between the chloride and hydroxide end members,and the structure of which shows similarities with α-Fs-M(monoclinic low-temperature-structure) and β-Fs-R(rhombohedral high-temperature-structure) separately. The pH value of chloride solutions affects the type of solid solutions formed. With increasing chloride concentration,although the amount of bound chlorides and solid solution formed increases,the ratio of bound to total chlorides decreases,and the pH value of the chloride solutions increases. The reduction in pH value of exposure solutions decreases chloride binding capacity by less formation of solid solutions. Although Ca ^2+ leads to the decreasing of pH value and solid solution formed,the chloride binding capacity of hydrated C 3A paste increases.