不同温度下合成沸石对铝酸钙水泥水化行为的影响

铝酸钙水泥的水化行为与物相组成、粉体粒径、水化温度、外加剂等因素密切相关。已有研究发现沸石结构矿物对铝酸钙水泥的水化行为影响显著,而作用机制有待进一步研究。本文采用XRD、SEM、FTIR、综合热分析以及电导率测试方法,系统研究了不同养护温度(20 ℃、25 ℃、30 ℃和40 ℃)下合成沸石对铝酸钙水泥水化行为的影响及作用机理。结果表明,合成沸石对铝酸钙水泥水化行为的影响与不同养护温度下离子浓度有关。在20 ℃养护时,铝酸钙水泥的溶解程度较低且沸石具有超高的比表面积及离子吸附能力,离子浓度难以达到饱和,延长了诱导期,从而延缓了铝酸钙水泥的水化;在25~40 ℃养护时,沸石的微孔结构和超高比表面积为水化产物提供更多成核位点,进而促进了铝酸钙水泥的水化。此外,合成沸石的引入有效消除了铝酸钙水泥在25 ℃养护时的异常凝结行为。

Effect of Synthetic Zeolite on Hydration Behavior of Calcium Aluminate Cement at Different Temperatures

The hydration behavior of calcium aluminate cement (CAC) is mainly affected by phase composition, particle size, curing temperature, and additive, etc. Research works revealed that the zeolite-type minerals would affect the hydration behavior of CAC, while the specific mechanism should be further investigated. Therefore, the hydration behavior and the detailed mechanism ofCAC containing zeolite at various curing temperatures (20 ℃, 25 ℃, 30 ℃ and 40 ℃) were investigated, through taking XRD, SEM, FTIR, thermal analyses and electrical conductivity tests. The results show that the effect of synthetic zeolite on the hydration behavior of CAC is dominated by the ion concentration at corresponding temperature. At 20 ℃, the low solubility of CAC leads to low ion concentration, meanwhile, the ultra-high specific surface area of synthetic zeolite hinders the saturation of ions, which prolongs the induction period and thus delays the hydration of CAC. In comparison, the pore structure and ultra-high specific surface area of zeolite provide more nucleation sites for hydrates at 25~40 ℃, which facilitate the hydration of CAC. In addition, the introduction of synthetic zeolite effectively eliminates the abnormal setting behavior of CAC cured at 25 ℃.