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为探索地质聚合物收缩补偿途径,研究了不同MgO掺量地质聚合物试体在不同养护条件(室温和38℃,相对温度RH>95%)下的变形行为,并采用X射线衍射、热重分析等测试方法研究掺入MgO地质聚合物的组成,分析了MgO影响地质聚合物变形行为的机理。结果表明:MgO对地质聚合物的变形行为有明显影响,且随养护条件不同而差异显著;掺入MgO可减小地质聚合物同龄期试体收缩,且掺量越大,减缩越大,但在通常养护条件下均没有表现出在波特兰水泥体系中显著的收缩补偿效应。MgO在地质聚合物中参与反应,且在不同养护条件下的反应机制有显著差异:常温条件下MgO优先与游离的[SiO4]4–反应生成高吸水性的硅酸镁凝胶;提高养护温度更利于促进地质聚合反应,加速对[SiO4]4–的消耗,从而抑制硅酸镁凝胶的形成。
In order to explore the ways of compensating the shrinkage of geopolymer, the deformation behaviors of geopolymers with different MgO content under different curing conditions (room temperature and 38 ℃, relative humidity RH> 95%) were studied. The XRD, Analysis and other test methods to study the composition of MgO geopolymer, and analyze the mechanism of MgO affecting the deformation behavior of geopolymer. The results show that MgO has a significant effect on the deformation behavior of geopolymer, and has significant difference with different curing conditions. MgO doping can reduce the shrinkage of geosynthetic polymer during the same age, and the larger the dosage, the larger the reduction, Under normal curing conditions, no significant shrinkage compensation effect was observed in the Portland cement system. MgO is involved in the reaction of geopolymers, and there are significant differences in the reaction mechanism under different curing conditions: MgO preferentially reacts with free [SiO4] 4- to produce super absorbent polymer magnesium silicate gel under normal temperature conditions; increases the curing temperature More conducive to promoting geological polymerization reaction, accelerate the consumption of [SiO4] 4-, thereby inhibiting the formation of magnesium silicate gel.