Modified random hierarchical bundle model for predicting gas permeability of cement-based materials

Permeability is a fundamental property indicating the durability of cement-based materials, predicted according to the material's pore size distribution (PSD). The random hierarchical bundle model is a promising approach based on a random hierarchical assembly of capillary segments to estimate the permeability of porous media. However, the original model neglected the slippage effect during gas penetration-a common occurrence in cement-based materials and other low-permeability porous media. Thus, we considered this effect in a modified model proposed herein, and the permeability of cement-based materials can be directly predicted using the PSD obtained via mercury intrusion porosimetry. Compared with data from experiments and literatures for various mortars and concretes with permeabilities ranging over 3 orders of magnitude, the results revealed that this modified model can accurately predict the intrinsic permeability and Klinkenberg constant. Moreover, this model can predict the intrinsic permeability and apparent permeability of various gases and porous media.

Automated summary

Permeability is a fundamental property of cement-based materials and can be predicted by examining the material's pore size distribution. The random hierarchical bundle model is a promising approach for estimating permeability, but the original model neglected the slippage effect during gas penetration. In this study, a modified model that considers this effect was proposed, and the permeability of cement-based materials can be directly predicted using the pore size distribution obtained via mercury intrusion porosimetry. The results showed that this modified model accurately predicts permeability for various mortars and concretes, and can also predict permeability for different gases and porous media.