Experimental study on gas permeability of cement-based materials

Abstract

Gas permeability is an important property associated with the durability of cement-based materials. In this study, an experimental method based on applying a quasi-stationary flow is adopted to evaluate the gas permeability of cement-based materials. The results indicate that the intrinsic permeability of dried cement-based materials is affected by the addition of limestone powder, fly ash, and aggregate. The Katz-Thompson equation could predict the intrinsic permeability by using the capillary porosity, average diameter, and pore tortuosity. The intrinsic permeability of partially saturated cement-based materials decreases when the water saturation increases. The Van Genuchten-Mualem model could describe the relative gas permeability of partially saturated cement-based materials, and the model parameters n value between 1 and 2 while m value ranging from 0.64 to 0.69 for cement and mortar. Moreover, the power function relationship between the intrinsic permeability and Klinkenberg constant of cement-based materials has also been corroborated. Finally, a prediction model of gas permeability of cement-based materials under arbitrary water saturation and pressure gradient is proposed.