Numerical simulation of moisture transport in concrete based on a pore size distribution model

• Pore size distribution of concrete was presented by a multi-Rayleigh–Ritz model.
• Moisture transport experiments under different conditions were conducted.
• Microcracks had greater influence on the concrete drying rate.
• Microcracks influenced transport rates in unwetted and wetted regions differently.
• Large capillaries influenced transport rates in both wetted and unwetted regions.

This paper presents a numerical approach for predicting moisture transport in concrete based on pore size distribution represented by a multi-Rayleigh–Ritz model that includes gel pores, small and large capillaries, and microcracks. The comparisons between the predicted pore size distributions and the mercury intrusion porosimetry results indicate that several small capillaries with diameters less than 20 nm may be connected to smaller gel pores. Moisture transport experiments under different atmospheric conditions were conducted to verify the proposed approach. The comparison between the predicted and measured internal relative humidity values showed acceptable agreement. The simulation results showed that microcracks had greater influence on the concrete drying rate than the other pore components. Results also revealed that more large capillaries caused a larger moving rate of the wet front and a larger moisture transport rate in the unwetted region.