环氧乳液改性水泥基材水化过程的硬化机理

极端环境和复杂荷载条件对混凝土结构的材料性能提出了更高的要求,聚合物通过改性水泥基材提高混凝土性能的方法已经得到了广泛应用。本研究为揭示环氧乳液改性水泥基材水化过程的硬化机理,通过等温放热试验分析环氧乳液对水泥水化放热过程的影响,结合原位XRD技术跟踪水泥主要矿物熟料和水化产物在水化反应早期的相含量发展。研究结果表明,环氧乳液对水泥水化的阻滞作用与环氧颗粒、水泥矿物熟料和水化产物之间的相互作用有关,并随着水化时间的延长,相互作用效果越明显。在水泥胶凝体系中,环氧乳液会减缓水化放热速率,降低水化放热峰值,减少累积放热量。环氧乳液通过抑制水泥矿物(C₃S、C₃A、石膏)的溶解和水化产物(钙矾石、氢氧化钙)的析出,延缓硅酸盐反应和铝酸盐反应;环氧乳液对水泥水化的影响随着其掺量的增加而增强。

Hardening Mechanism on Hydration Process of Epoxy Latexes-Modified Cementitious Materials

Extreme environment and complex load conditions put forward higher requirements for the material properties of concrete. The method of improving concrete performance by modifying cement-based material with polymer has been widely used. To reveal the hardening mechanism of the hydration process of epoxy latexes-modified cementitious materials, the influence of epoxy latexes on the hydration process of cement hydration was studied by isothermal calorimetry, and the phase evolution of the cement clinker minerals and hydration products was tracked by in-situ XRD. The results show that the retardation effect of epoxy latexes on cement hydration is related to the interaction among epoxy particles, cement clinker minerals and hydration products, and the interaction effect becomes more obvious with time-dependent. When epoxy latexes are added into the cement paste, the heat-generation rate slows down, and the heat flow peak and cumulative heat generation reduce. Epoxy latexes can delay silicate reaction and aluminate reaction by inhibiting the dissolution of cement minerals (C₃S, C₃A and gypsum) and the precipitation of hydration products (ettringite and portlandite). The effect of epoxy latexes on cement hydration increases with the increase of its content.