钙矾石对水泥石膨胀和力学性能的作用机理与本构模型

Ettringite is one of the main hydration products in cementitious materials, particularly in portland cement-ettringite based expansive agent system and calcium sulfoaluminate cement, and plays an important role in the volume stability and mechanical properties of hardened cement paste. Since no effective tool is available for designing ettringite formation, it is difficult to predict and control the action of ettringite formation on the properties of hardened cement paste. Therefore, concrete cracking often occurs, due to either too small or too big expansion from ettringite formation..This project aims to explore the mechanism of the ettringite-related expansion and mechanical properties development, by investigating the formation of ettringite in developing microstructure and its effect on the properties of hardened cement paste. Based on Prof. Zhongwei Wu’s “center-body hypothesis”, the constitutive model will be established to quantify the relation between ettringite formation with the expansion and mechanical properties of hardened cement paste. A concrete material design method will then be developed based on the approaches of controlling hydration process and optimizing microstructure. .The investigation of the action of ettringite formation will lead to a better understanding of the advantages and disadvantages of ettringite in hardened cement paste. The constitutive model will be the breakthrough of mathematical modelling of “center-body hypothesis”. The constitutive model, defining quantitative relation between ettringite formation to expansion and mechanical properties, will provide an effective tool for utilizing ettringite to tailor the expansion and mechanical properties of hardened cement paste.

钙矾石是水泥（特别是硅酸盐水泥-膨胀剂复合体系和硫铝酸盐水泥）的重要水化产物之一，它对水泥石的体积稳定性和力学性能起着重要的作用。工程应用中发现，由于缺乏理论模型和有效设计手段，导致钙矾石生长过程及其对水泥石性能的影响难以预测和控制，混凝土时常发生膨胀不够而收缩开裂或膨胀过大而涨裂的现象。.本项目拟通过研究钙矾石生长过程与微观结构的匹配关系及其对水泥石性能的影响，揭示钙矾石对水泥石膨胀和力学性能的作用机理。基于吴中伟院士提出的“中心质假说”，建立水泥石膨胀和力学性能本构模型。开发基于水化过程调控和微观结构优化技术的混凝土精细化设计方法。.对钙矾石作用机理的探究将更全面地认识钙矾石在水泥石中的利害作用。新建的本构模型将是“中心质假说”在模型化方面的突破与发展，它将建立起钙矾石生成量与水泥石膨胀和力学性能之间的定量关系，为调控水泥石膨胀和力学性能提供量化计算手段，实现钙矾石膨胀的“趋利避害”。

钙矾石是水泥（特别是硅酸盐水泥-膨胀剂复合体系和硫铝酸盐水泥）的重要水化产物之一，它对水泥石的体积稳定性和力学性能起着重要的作用。采用钙矾石作为膨胀组分可有效控制混凝土早期的收缩，减少收缩开裂，但由于缺乏理论模型和有效设计手段，导致钙矾石生长过程及其对水泥石性能的影响难以预测和控制，混凝土时常发生膨胀不够而收缩开裂或膨胀过大而涨裂的现象。本项目拟通过研究钙矾石生长过程与微观结构的匹配关系及其对水泥石性能的影响，揭示钙矾石对水泥石膨胀和力学性能的作用机理。项目结合吴中伟院士提出的“中心质假说”，分析水泥基材料晶体-胶体的相互作用关系及其对宏观性能的影响规律；提出“自应力假说”并基于该假说分析水化阶段钙矾石生长对混凝土体积稳定性的影响，建立水泥石膨胀和力学性能本构模型。开发基于水化过程调控和微观结构优化技术的混凝土精细化设计方法。对钙矾石作用机理的探究将更全面地认识钙矾石在水泥石中的利害作用。新建的本构模型将是“中心质假说”在模型化方面的突破与发展，它将建立起钙矾石生成量与水泥石膨胀和力学性能之间的定量关系，为调控水泥石膨胀和力学性能提供量化计算手段，实现钙矾石膨胀的“趋利避害”。为钙矾石类膨胀剂在混凝土施工中应用提供理论指导。