RESEARCH ON TENSILE CREEP MODEL BASED ON DEGREE OF HYDRATION FOR EARLY-AGE CONCRETE

This paper investigates the tensile creep of early-age concrete. Firstly, improvements are made on the Kelvin model based on degree of hydration. An incremental calculation approach is given for computing tensile creep. Then tests concerning the direct tensile strength, the tensile modulus of elasticity and tensile creep are conducted through a custom-made loading frame. Moreover, the degree of hydration of the cement paste is obtained by thermogravimetric analysis. Lastly, the calculated parameters of the improved creep model are determined through the creep results of the specimens loaded for 1 day. This improved model is used to check the development of the strain at other loading ages. The results show that the degree of hydration develops rapidly during the early age, and the tensile creep is very sensitive to the loading age; the earlier the loading age is, the greater the specific creep of concrete becomes; the creep model containing three Kelvin units based on degree of hydration could be used to describe the tensile creep of early-age concrete well.