改性硅溶胶对水泥基复合材料力学性能的影响及机制

Effect of Modified Silica Sol on Mechanical Properties of Cement-Based Composites and Its Mechanism

使用硅烷偶联剂KH560对纳米硅溶胶进行改性从而提升其分散性,并以硅溶胶、改性硅溶胶为掺和料,制备了不同含量的水泥基复合材料试件。采用Zeta电位仪、万能试验机分别测试改性前后硅溶胶的粒径分布及复合材料的力学性能,并采用X射线衍射(XRD)以及扫描电镜(SEM)对其增强机制进行分析。结果表明:硅溶胶消耗了水泥水化生成的Ca(OH)2,生成了对混凝土强度有利的水化硅酸钙凝胶。当硅溶胶、改性硅溶胶质量分数分别为1.5%、1%时,水泥基复合材料的力学性能最好,微观结构均质而密实。其中,改性后的硅溶胶对水泥基复合材料的力学性能增强最为显著。

Silane coupling agent KH560 was used to modify nano-silica sol to improve its dispersibility,and silica sol and modified silica sol were used as admixtures to prepare cement-based composite specimens with different mass fractions.Zeta potentiometer and universal testing machine were used to test the particle size distribution and mechanical properties of the composite before and after modification,and XRD and SEM were used to analyze the strengthening mechanism.The results show that the Ca(OH)2 generated by ce⁃ment hydration is consumed by the silica sol and the calcium silicate hydrate condensate which is beneficial to the strength of concrete is formed.When the mass fraction of silica sol and modified silica sol is 1.5%and 1%,respectively,the mechanical properties of cement-based composites are the best,and the micro⁃structure is homogeneous and dense.Among them,the mechanical properties of cement-based composites are enhanced most significantly by the modified silica sol.