活性粉末混凝土材料的收缩机理及控制方法

Reactive Powder Concrete (RPC) has outstanding mechanical properties and durability, which makes it suitable for the construction in severe environment, such as cold and coastal regions. However, the shrinkage of reactive powder concrete is dramatically larger than ordinary concrete in the same curing condition. Larger shrinkage might cause localized stress concentration and shape distortion for prefabricated unit with complex section in steam curing. It also causes the pre-stressing loss and interface cracking for cast in situ unit. The shrinkage problem restricts extensive engineering application of reactive powder concrete. The shrinkage of reactive powder concrete in various curing condition is measured. Cooperate with the investigation of hydrating kinetics, micro-structure of hardened paste, hydration degree of binder, relative humidity of material, surface chemistry properties of paste solution, the change rules and micro mechanisms of reactive powder concrete shrinkage is clarified. Combined with the basic theories of concrete shrinkage, the influencing mechanisms of curing condition on the chemical, autogenous and drying shrinkage is discussed, separately. After comprehensive consideration of mechanical properties, durability and shrinkage of reactive powder concrete, the reasonable and effective shrinkage controlling methods are proposed. This research provides a solution for shrinkage problem of reactive powder concrete in various curing conditions. It also provides the scientific foundation for technology development and engineering application of reactive powder concrete.

活性粉末混凝土具备优异的力学性能和耐久性能，十分适宜高寒和沿海地区等恶劣环境下的工程建设。然而活性粉末混凝土的收缩明显大于同条件养护的普通混凝土，可能出现复杂截面构件蒸养过程中局部应力集中和尺寸畸变、现浇构件接缝部位开裂和预应力损失等问题，对其工程应用产生不利影响。本项目通过测定不同养护条件下活性粉末混凝土收缩随龄期的发展，配合材料水化动力学参数、浆体微结构、胶凝材料水化程度、内部相对湿度、浆体溶液表面化学特性等微观试验，掌握不同养护制度下活性粉末混凝土收缩的变化规律及其微观机理；结合混凝土收缩相关基础理论，明确养护制度变化对活性粉末混凝土材料各龄期的化学收缩、自收缩和干燥收缩的影响机理；综合考虑力学性能、耐久性和收缩变化，筛选合理有效的活性粉末混凝土收缩控制关键技术。本项目为解决不同养护制度活性粉末混凝土材料收缩问题提供理论支持，为活性粉末混凝土技术发展与工程应用提供科学基础。

测定了不同养护条件下活性粉末混凝土收缩随龄期的发展，配合材料水化动力学参数、浆体微结构、胶凝材料水化程度、内部相对湿度、浆体溶液表面化学特性等微观试验，掌握了不同养护制度下活性粉末混凝土收缩的变化规律及其微观机理；结合混凝土收缩相关基础理论，明确了养护制度变化对活性粉末混凝土材料各龄期的化学收缩、自收缩和干燥收缩的影响机理；综合考虑力学性能、耐久性和收缩变化，提出了合理有效的活性粉末混凝土收缩控制关键技术。本项目为解决不同养护制度活性粉末混凝土材料收缩问题提供理论支持，为活性粉末混凝土技术发展与工程应用提供科学基础。