硅烷偶联剂/偏高岭土基地聚合物水化热及动力学研究

Hydration Heat and Hydration Kinetics of Silane Coupling Agent/Metakaolin Based Geopolymers

为了研究硅烷偶联剂对偏高岭土基地聚合物水化的影响,通过水化热和水化动力学分析,研究了不同种类及不同掺量的硅烷偶联剂对地聚合物水化进程的影响,并结合SEM-EDS对地聚合物早期水化微观形貌进行分析。结果表明,随着硅烷偶联剂掺量的增加,地聚合物的凝结时间延长。掺入硅烷偶联剂后地聚合物在加速期水化放热加快,进入减速期后未掺硅烷偶联剂的地聚合物的放热速率比掺入硅烷偶联剂的快,此时期硅烷偶联剂抑制地聚合物的水化进程。硅烷偶联剂的掺入对地聚合物的累积水化放热量影响不大,所有试样的累积水化放热量基本相同,相差在2%以内。结合水化动力学参数发现,水化过程大致分为加速期、减速期和稳定期。在加速期,水化反应被化学催化反应控制,掺入硅烷偶联剂的体系会发生强烈的化学反应,水化速率加快;在减速期,水化产物在颗粒表面形成薄膜,反应阻力加大,水化速率减缓;稳定期则由扩散机制控制反应过程。结合SEM-EDS图发现,硅烷偶联剂的掺入未改变地聚合物水化产物的矿物组成,但能起到桥接作用,使地聚合物结构更加致密。

Akinetic study by hydration heat was reported to research the influences of different dosages and kinds of silane coupling agent on the hydration process of metakaolin-based geopolymer,and the micro-morphology of early hydration of geopolymer was analyzed by SEM-EDS.The results showed that the setting time of geopolymer with silane coupling agent was longer than that of neat geopolymer,and the setting time was prolonged with the increase of silane coupling agent.The hydration exothermic rate of geopolymer with silane coupling agent accelerated during the acceleration period and the exothermic rate of neat geopolymer is faster than that of geopolymer with silane coupling agent after entering the deceleration period.During this period,silane coupling agent inhibited the hydration process of geopolymer.The addition of silane coupling agent had little effect on the cumulative hydration heat of geopolymer and the cumulative hydration heat of samples was almost the same,the difference was less than 2%.The hydration process of geopolymer could be divided into acceleration,deceleration and stable periods by analyzing the hydration kinetic parameters.The hydration was controlled by chemical catalysis reaction during acceleration period and the strong chemical reaction occurred with the addition of silane coupling agent,which accelerated the hydration rate.The hydration products formed films on the surface of particles during the deceleration period,which increased the reaction resistance and retarded the reaction rate.During the stable period,the reaction process was controlled by diffusion mechanism.The addition of silane coupling agent didn’t change the mineral composition of the hydration products of geopolymer by observing SEM images,but silane coupling agent acted as a bridge to make the structure of geopolymer more compact.