Hydration of cement in concrete
The hydration of cement is accompanied by heat generation, development of micro-pore structures and associated mechanical strength in the hardening cement paste, mortar or concrete. Cement hydration is a phenomenon responsible for creating the hardened cement matrix of concrete and the sole cause of the temperature rise during hardening. It is an essential component for evaluating concrete performance in a rational design system that incorporates thermal cracking control, as well as other effects such as autogenous/ drying shrinkage and the development of strength and microstructure. For these reasons, a model of the hydration of the cement in concrete must be developed. This chapter focuses on the heat-generation process for the cement in concrete. A strong correlation exists between heat generation and the degree of hydration in each constituent clinker mineral and the other binders. To control the risk of thermal cracking in the early stages as well as evaluate the long-term durability of concrete structures, we must be able to quantitatively predict the hydration process over time. The hydration model presented here adopts a multi-component system and applies Arrhenius’s law of chemical reaction. When combined with hydration, microstructure development, and moisture transport phenomena, the model faithfully simulates the hardening process for concrete.