基于温度-应力试验的自生体积变形计算起点的研究

针对标准试验方法在混凝土自生体积变形计算起点方面尚存在的问题,本文以微膨胀抗冲磨混凝土为研究对象,对ASTM C1074活化能测试方法进行改进,获得更为准确的胶凝材料水化反应活化能,并基于活化能计算得到实际温度条件下试件的等效龄期;利用温度-应力试验的特点,以第一零应力对应的等效龄期作为自生体积变形的有效计算起点,在日本混凝土学会提出的混凝土自生体积变形模型基础上,以自生体积变形最大膨胀值作为分界点分段模拟分界点前后的变形,建立以温度-应力试验第一零应力时间为计算起点的自生体积变形模型,为准确建立抗裂机理模型提供参考依据。

Study on calculation starting point of autogenous volume deformation based on thermal stress test

For the starting point problem existed in calculating autogenous volume deformation by the standard test methods, ASTM C1074 test method for activation energy has been improved, taking the expansive abrasion-resistant concrete as the research object. More accurate activation energy of cementitious materials is obtained,and equivalent age of the specimen can be calculated under the actual temperature conditions based on the activation energy. Using the advantageous characters of thermal stress test and taking the equivalent age corresponding to the first zero stress as the effective starting point, an improved autogenous volume deformation model has been established on the basis of the model put forward by Japan Concrete Institute Conference. The improved model takes the maximum expansion value of autogenous volume deformation as a cutoff point and can simulate the deformation before and after the point separately, which provides reference for setting up a more accurate anti-crack model.