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研究了早龄期混凝土的拉伸徐变特性,首先对基于水化程度的开尔文模型进行改进,并建立拉伸徐变的增量计算方法;然后采用门式加载设备对早龄期混凝土的直接拉伸强度、拉伸弹性模量以及拉伸徐变进行试验研究,通过热重分析得到水泥浆体的水化程度;最后利用1 d龄期的徐变试验结果确定改进模型的计算参数,并对其他龄期拉伸应变进行验算。研究结果表明,早龄阶段混凝土的水化程度发展较快,拉伸徐变对早龄混凝土的加载龄期非常敏感,加载龄期越早,混凝土的徐变度越大;基于水化程度包含3个开尔文单元的徐变模型可以较好地描述早龄期混凝土拉伸徐变特征。
The tensile and creep properties of early age concrete are studied. Firstly, the Kelvin model based on the degree of hydration is improved and an incremental calculation method of tensile creep is established. Then, Tensile strength, tensile modulus of elasticity and tensile creep were studied. The degree of hydration of cement paste was obtained by thermogravimetric analysis. Finally, the calculation parameters of the improved model were determined by 1-year creep test Tensile strains of other age check. The results show that the early stage of hydration of concrete develops rapidly, and the tensile creep is very sensitive to the loading age of early age concrete. The earlier the loading age, the greater the creep of concrete. Based on the degree of hydration, The creep model of three kelvin units can well describe the tensile creep characteristics of early aged concrete.