纳米二氧化硅对苯丙共聚物/水泥复合胶凝材料凝结硬化的影响

Effect of Nano-silica on the Setting and Hardening Process of Styrene-acrylic Ester/Cement Composite Cementitious Material

采用纳米二氧化硅作为调凝物质以期解决苯丙共聚物/水泥复合胶凝材料凝结硬化慢的问题。通过测定纳米二氧化硅改性苯丙共聚物/水泥复合胶凝材料的凝结时间及早期强度,分析纳米二氧化硅对复合胶凝材料凝结硬化过程的影响;采用等温量热法测定纳米二氧化硅改性苯丙共聚物/水泥的水化热,并采用X射线衍射仪对其水化产物进行表征;综合以上分析结果探讨纳米二氧化硅的作用机制。结果表明:掺入二氧化硅能有效促进复合胶凝材料的凝结硬化,二氧化硅掺量为1.25%时促进作用最为显著;掺入纳米二氧化硅可促进铝酸三钙和硅酸三钙的水化,加快钙钒石和氢氧化钙的生成,缩短复合胶凝材料的水化诱导期和加速期,加快水泥水化进程,从而缩短凝结时间,提高早期强度。

To solve the problem of retardation existing in the setting and hardening process of styrene-acrylic ester/cement (SAE-cement) composite cementitious material, nano-silica served as setting modifying admixture in this work. By measuring the setting time and initial strength of nano-silica modified SAE-cement composite cementitious material, the effect of nano-silica on the setting and hardening process of composite cementitious material was analyzed. To explore the work mechanism of nano-silica, the hydration heat of nano-silica modified SAE-cement composite cementitious material was determined by isothermal calorimetry, and its hydration products were examined by X-ray diffraction. The results show that the addition of nano-silica can effectively promote the setting and hardening process of composite cementitious materials, and the effect of 1.25% dosages is the most significant. It also indicates that adding nano-silica accelerates the formation of ettringite and calcium hydroxide by promoting the hydration of tricalcium aluminate and tricalcium silicate, shortens the hydration induction period and acceleration period of the composite cementitious material, accelerates the hydration process, thereby shortening the setting time and increasing the early strength.