Temperature Effect on Water Diffusion, Hydration Rate, Creep and Shrinkage
Temperature and heat transfer have a large effect on concrete creep as well as on the moisture transport. Great advances in this regard have been made in research motivated by concrete nuclear power plant structures, and more recently by tall building fires and tunnel fires. First we review the mathematical modeling of heat transfer in concrete, including the effect of heat on cement hydration and the heating caused by early-age hydration. Then we turn attention to combined heat and moisture transfer and hygrothermal effects in heated concrete. To model the strains and stresses at high temperature, we discuss the combined thermal and hygral volume changes, the extension of creep models to high temperatures, and explain the phenomena of explosive thermal spalling in fire and surface layer ablation by means of microwave heating. We emphasize the efficacy and necessity of using the finite volume method for the moisture and heat transfer in concrete in the case of a moving dry–wet interface. Finally, we discuss the mass, momentum, and energy balance laws, which provide the theoretical basis for the modeling of hygrothermal processes in multiphase media.