混凝土膨胀剂是一种广泛使用的混凝土特种材料。我国是膨胀剂生产和使用量最大的国家，但是对于膨胀剂的作用机理的基础研究不多。这不利于膨胀剂的生产和使用。本课题针对现在大量使用的氧化钙-硫铝酸钙型的双膨胀源膨胀剂的作用机理进行研究，同时关注基于氧化镁的多膨胀源膨胀剂的作用机理和效果。本课题将开展多膨胀源膨胀剂的水化反应的研究，确定其水化动力学。研究各种因素对多膨胀源膨胀剂的水化反应和补偿收缩行为的影响，以及膨胀剂的水化反应与硅酸盐水泥的水化反应之间的相互影响。研究不同膨胀源的膨胀剂在不同强度等级、不同养护条件下的补偿收缩混凝土中的表现；以及对于补偿收缩混凝土性能的影响规律。本课题成果将为开发新型膨胀剂，科学合理使用膨胀剂，调控补偿收缩混凝土的性能，提出降低混凝土结构开裂风险的技术措施打下理论基础。为在现行国家的膨胀剂产品标准中拓展膨胀剂品种提供实验数据支撑。

Concrete expansive agent is a widely used special additive. China is the largest manufacturer and user of expansive agent worldwide. It is lack of fundamental research about the reaction mechanism of expansive agent, which hinders its production and utilization. This project focuses on the reaction mechanism of expansive agent of twin expansive components of expansive agent based on CaO- C4A3$ system, which is main variety now in China and deals with the reaction mechanism and effect of multi expansive components of expansive agent based on MgO. The hydration of these expansive agents will be studied and their reaction kenetics will be determined. The influencing factors of hydration and shrinkage-compensating behavior of multi expansive components of expansive agents will be studied. The interaction of Portland cement and expansive agent will be investigated. The behavior of different expansive agents in shrinkage-compensating concrete cured in different conditions and with different strength will be investigated. The results from this project will be a theoretical foundation of development of new type of expansive agent, suitable use of expansive agent. The performance of shrinkage-compensating concrete can be adjusted to reduce the risk of cracking of concrete structure based on the results of this project. The experimental data can support the involvement of new type of expansive agent in national standard.