Improved predictions of permeability properties in cement-based materials: A comparative study of pore size distribution-based models

• Published in: Construction & building materials 2024-01, Vol.411, p.133927, Article 133927
• Main Authors: Xiong, Qing Xiang, Tong, Liang-yu, Meftah, Fekri, Zhang, Yunsheng, Liu, Qing-feng
• Format: Article
• Language: English
• Subjects: Cement mortars; Engineering Sciences; Katz-Thompson model; Multimodal pore size distribution; Permeability; Slippage effect
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2023.133927

•Permeability of mortars was estimated by multimodal pore size distributions model.•Applicability of the K-T model and PSD-based models was validated and compared.•Saturation degree variations of C-S-H structure caused abnormal between water and gas permeability.•Slippage effects between gas molecules and pore walls decreased gas permeability. Permeability is a fundamental physical property of a cement-based material and is closely related to its pore structure. This study developed an improved model for permeability prediction of cementitious materials with a function of the pore size distribution (PSD), in which PSD is simulated from single and compound lognormal distribution functions, respectively. The efficiency of the improved model is demonstrated by calculating permeability for mortars and pastes available in the literature. It is found that, first, for cementitious materials with unimodal PSD, the single lognormal distribution function is adequate to describe the pore structures. In contrast, for cementing mixtures presenting multimodal PSD, the compounded lognormal distribution function is highly recommended to cover a wide range of pore components. Second, the permeability model based on the compound PSD can predict well permeability to gas intrusion, whereas the single PSD-based model is applicable for calculating permeability via water intrusion. Furthermore, slippage effect and water saturation degree are introduced in the PSD-based model. Results prove that the corrected gas permeability model from the compound PSD performs well in estimating the gas permeability in unsaturated states. Finally, the compound PSD-based model is extended by considering varying porosities and relative humidities, which can be used to quantitively describe permeability when cementitious materials undergoing pore structure degradation induced by durability issues.