Moisture loss characteristics of cement-based materials under early-age drying and shrinkage conditions

Moisture flow through hydrating cement-based materials under early-age drying and shrinkage conditions is studied. The mechanism of drying of cementitious materials as a porous media is described. A dual-stage methodology for modeling the drying is presented based on surface moisture transfer and internal moisture transport characteristics. The proposed model for the internal moisture transfer simulates initial constant drying rate period (stage I) as a funicular liquid water transport stage, succeeding by falling drying rate period (stage II) as a vapor diffusion transport phenomena. The methodology is applied to the results of drying experiments under low and normal pressure conditions and verified by a Finite Element (FE) analysis. Results show that developed model is capable of predicting experimental data during the drying of cement-based materials and captures the changes in internal and surface moisture transfer parameters as the drying time proceeds.