–10℃条件下氯化钙溶液对硫铝酸盐水泥性能的影响

Effect of Calcium Chloride Solution on Performance of Calcium Sulphoaluminate Cement at –10 ℃

研究了–10℃条件下氯化钙冷溶液拌合冷硫铝酸盐水泥所获得浆体的凝结硬化及试样的强度发展、物相组成、显微结构和氯离子含量。结果表明:分别采用16%(质量分数)、28%氯化钙冷溶液拌合的浆体存在明显而持续的水化温升过程,证实了该条件下水泥水化的启动与持续进行;提高溶液浓度,浆体达到水化温升最高温度对应的时间延长,从16%时约90 min延长至28%时约150min。采用16%氯化钙冷溶液拌合,浆体凝结硬化快、试样抗压强度高(初凝和终凝时间分别为15min和24 min,1 d和28 d抗压强度分别为41.0 MPa和85.2 MPa);而采用28%氯化钙冷溶液拌合,浆体凝结硬化慢、试样抗压强度低(初凝和终凝时间分别为85 min和155 min,1 d和28 d抗压强度分别为24.3 MPa和57.7 MPa)。溶液浓度16%时,水化产物主要为钙矾石,以针棒状晶体存在,试样中结合氯离子含量极低;而溶液浓度28%时,水化产物主要为F盐,以花瓣形六方板状晶体存在,试样中含有0.95%左右结合氯离子。–10℃条件下采用同处于负温环境的氯化钙冷溶液拌合冷硫铝酸盐水泥可实现冷物料拌合,防止浆体结冰,保证水泥持续水化,其中16%~20%氯化钙溶液拌合时可以获得较短凝结时间和较高强度。

The influence of cold CaClsolution on the setting behavior, strength development, mineralogical composition,microstructure, and chloride content of calcium sulphoaluminate(CSA) cement at –10 ℃ was investigated. The results show that there is a significant and persistent temperature peak in CSA cement pastes mixed with 16% and 28% cold CaClsolution, so CSA cement can hydrate continuously. The temperature peak retards from 90 min to 150 min as the solution concentration increases from 16% to 28%. The pastes with 16% CaClsolution set quickly and the compressive strength is high(initial setting time 15 min and final setting time 24 min, compressive strength 41.0 MPa at 1 day and 85.2 MPa at 28 days);while the pastes with 28% CaClsolution set slowly and the compressive strength is low(initial setting time 85 min and final setting time 155 min, compressive strength 24.3 MPa at 1 day and 57.7 MPa at 28 days). Ettringite is the primary hydration product and its morphology is needle in hydrated pastes with 16% CaClsolution. The Friedel’s salt turns to be dominant and the morphology is hexagonal plate in hydrated pastes with 28% CaClsolution. There is little binding chloride for 16% CaClsolution and 0.95% binding chloride for 28% CaClsolution. In the presence of CaClsolution, the CSA cement can hydrate continuously at –10 ℃. Furthermore, a shorter setting time and a higher strength can be obtained in CSA cement pastes mixed with 16%-20% CaClsolution.