Prediction of Temperature and Moisture Distributions in Hardening Concrete By Using a Hydration Model

Abstract

This paper presents an integrated procedure to predict the temperature and moisture distributions in hardening concrete considering the effects of temperature and aging. The degree of hydration is employed as a fundamental parameter to evaluate hydrothermal-mechanical properties of hardening concrete. The temperature history and temperature distribution in hardening concrete is evaluated by combining cement hydration model with three-dimensional finite element thermal analysis. On the other hand, the influences of both self-desiccation and moisture diffusion on variation of relative humidity are considered. The self-desiccation is evaluated by using a semi-empirical expression with desorption isotherm and degree of hydration. The moisture diffusivity is expressed as a function of degree of hydration and current relative humidity. The proposed procedure is verified with experimental results and can be used to evaluate the early-age crack of hardening concrete.

Effect of fly ash on the kinetics of Portland cement hydration at different curing temperatures

“…The shrinking-core model, which was originally developed by Tomosawa [17] and modified in [3][4][5], is used in this study to simulate the development of cement hydration. This model is expressed as a single equation consisting of three coefficients: d k the reaction coefficient in the induction period; e D the effective diffusion coefficient of water through the C-S-H gel; and r k a coefficient of the reaction rate of cement as shown in Eq.…”

“…This effect is accounted for by the term 0 / S S w in Eq. (1) where w S is the effective surface area of the cement particles in contact with water and 0 S is the total surface area if the surface area develops unconstrained [3][4].…”

“…(2) where B and C are the coefficients determining this factor [3][4]; B controls the rate of the initial shell formation and C controls the rate of the initial shell decay.…”

“…For ordinary Portland cement paste, Park [3][4] and Maruyama [5] have demonstrated the use of this model to simulate the hydration of cement in general and of the different cement components. Results showed good agreement between the model simulations and the experimental data.…”

Early-Age Cracking in Concrete: Causes, Consequences, Remedial Measures, and Recommendations

“…This model is able to describe the diffusion process occurring in early-age concrete. In the same year, Park [99] deduced three-dimensional finite element thermal analysis to predict the temperature and moisture distribution in hardening concrete. The fundamental parameter considered in his analysis was the degree of cement hydration.…”