Stresses and Cracking Caused by Hydration Heat in Massive Concrete Structures

Abstract

After development of the theory and analysis of the temperature [1], this paper analyzes the stresses and cracking caused by hydration heat in massive concrete wall. The analysis takes into account the fact that the adiabatic temperature rise and the creep model are based on Arrhenius’ theory which lead to nonlinear differential equations, and the cracks are modeled by Bazant’s crack band model [2]. The crack is divided into equal strips, and a numerical algorithm with step-by-step loading is developed to calculate the growth of the crack in each step. The interactions of temperature, stresses and cracking are computed by half-analytical iteration method. The systems of up to 360 nonlinear equations are solved in this paper. The following conclusions are drawn. A temperature increase has two mutually competing effects. Firstly, it accelerates creep, i.e. increase the creep rate. This indicates that the retardation or relaxation times should be reduced as temperature increases. Secondly, a temperature increase further causes an acceleration of hydration or aging, thereby indirectly also reducing creep. The placement temperature has a severe effect on cracking in massive concrete wall, the more the placement temperature, the earlier the crack happen, and the longer the crack length.