加载龄期对混凝土徐变的影响机理

Effect mechanism of loading age on concrete creep

基于水化产物的结晶动力学特性,推演了荷载下混凝土中水化产物的溶解-扩散-重结晶过程,建立了水化产物迁移理论及混凝土徐变的分析模型。试验研究了加载龄期分别为28、90、180 d的混凝土徐变行为。基于新建的水化产物迁移理论,分析了加载龄期对混凝土徐变的影响机理。研究表明,徐变与荷载下水化产物的溶解-扩散-重结晶过程直接相关,基于该过程分析建立的水化产物迁移理论可以系统地解释混凝土的徐变机理与行为。随着加载龄期的延长,水泥的水化程度不断提高,同时水化产物含量逐渐增加,基于水化产物迁移理论可知,单位应力下晶体的溶解量减小,徐变度也随之减小。

Based on the kinetics of hydration product,the dissolution-diffusion-recrystallization process of hydration product in concrete is analyzed.Then hydration product migration theory and the numerical model of concrete creep are built.The creep behavior with loading ages of 28 d,90 d and 180 d is conducted.Based on the proposed theory,the effect of loading age on concrete creep is analyzed.It can be found that concrete creep is related to the dissolution-diffusion-recrystallization process of hydration product.Hydration product migration theory can be used to explain the mechanism and behavior of concrete creep.As loading age increases,the hydration degree of cement also increases and the content of hydration product increases.The dissolution fraction of the crystal under unit stress decreases with the increase in loading age.Then concrete creep decreases as the loading age increases.