Finite-Element Simulation of Hydration and Creep of Early-Age Concrete Materials.

The thermal stress and tensile creep of early-age concrete that occur during the exothermic chemical reactions between water and cement may result in harmful cracks. Heat of hydration and creep of early-age concrete are described in this paper. An equation for evaluating hydration degree is presented, and a finite-element program for a thermal analysis of hydration heat is developed. Based on the theory of creep and heat of hydration of early-age concrete, the temperature and strains in a subway station structure were simulated using the finite element method. The predicted results are in good agreement with the site-measured data. A parametric analysis of ambient temperature and concrete slab thickness was also conducted. The analysis results indicate that it is not advantageous to reduce the temperature difference, whether the ambient temperature is too high or too low. Creep does not always reduce the undesirable tensile stresses; it may increase structural tensile stresses during the early-age stage of concrete. [ABSTRACT FROM AUTHOR]