chapter  3
112 Pages

Micro-pore structure formation and moisture transport

As the development of microstructure, hydration and moisture transport are intrinsically coupled (Chapter 1), an integrated approach is required for macro-scale computations of temperature and related stress models that make use of the sophisticated micro-scale material models. Therefore, the goal of this chapter is to develop analytical models of microstructure development based upon the hydration model of cement (Chapter 2) and fundamental solid models pertaining to each physical process. At the same time, an important consideration is that the formulations should be simple enough to be incorporated in a real-time computational scheme of heat and moisture transport in a full-sized structural concrete scenario from a practical view point. The development of a microstructure formation model is also necessary since mass transport characteristics are strongly dependent on it. This chapter presents the multi-scale modeling of micro-pore structures, moisture equilibrium and its transport as mutually interrelated thermodynamic events. The development of the pore structure at early ages is obtained using a pore structure development model based on the average degree of hydration. The predicted computational pore structures of concrete would be used as a basis for moisture transport computation. In this way, by applying a dynamic coupling of pore-structure development to both the moisture transport and hydration models, the development of strength along with moisture content and temperature can be traced with the increase in the degree of hydration for any arbitrary initial and boundary conditions.