A new analytical method to predict permeability properties of cementitious mortars: The impacts of pore structure evolutions and relative humidity variations

This research develops analytical models in respectively describing the water vapour sorption isotherm and permeability properties based on a probabilistic method for pore size distribution and two transformation models for pore radius of cementitious mortars. By adopting the water vapour sorption model, the water saturation degree in cement-based materials is acquired and the influence of ions on water vapour sorption isotherm is modelled by introducing the water activity in thermodynamic equilibrium relation between liquid and vapour phases. The results reveal that the presence of ions increases the susceptibility of mortars to be water-saturated. Additionally, intrinsic permeability and relative permeability of mortars are predicted and the reliability of the permeability model is investigated. Finally, the permeability model is further extended considering the evolu-tions of pore structure and variations of relative humidity when cementitious mortars are subjected to precipi-tation and dissolution, which attempts to give an understanding of interactions between permeability and evolved pore structure that are not yet very commonly mentioned in literature. Modelling results show that both pore size distribution and relative humidity significantly affect permeability properties of mortars, especially when the water saturation degree is large. This research provides a novel insight into quantifying the perme-ability of mortars undergoing pore structure degradations.

Automated summary

This research develops analytical models for describing the water sorption isotherm and permeability properties of cementitious mortars. The models incorporate a probabilistic method for pore size distribution and transformation models for pore radius. The influence of ions on water sorption and the evolution of pore structure are also investigated. The results demonstrate the significance of pore size distribution and relative humidity in determining the permeability of mortars.