Abstract

To better understand the macro transport properties and durability of cementitious materials, their microstructure should be characterised more accurately. This study investigated white cement mortars with different water-cement ratios, sand volume fractions, and curing ages. The water permeability was measured using a self-manufactured facility. The low-field nuclear magnetic resonance (LF-NMR) technique combined with the displacement method was used to test the pore size distributions (PSD) of total pores and connected regions. Two-dimensional mortar and pore-based matrix models were established to obtain the tortuosity of the transport path. The results show that the pore connectivity of the mortar ranges from 32% to 52%, and the tortuosity ranges from 1.428 to 1.542. The pore connectivity was spatially sensitive, and small pores were densely connected, linking large pores to form a pore network. Although capillary pores dominate the permeability, the role of gel pores cannot be ignored. Considering gel pores can improve the accuracy of the predicted water permeability by 80%. The relative error of the modified model is [-23.76%, 37.19%], which shows a significant improvement.