Abstract: Permeability directly determines the transport speed of harmful substances in porous volume of cement-based materials (such as concrete). Thus, it is the key to influence the durability of cement-based materials. Based on 3D pore structure and MIP (Mercury intrusion porosimetry) result of cement paste, the permeability of cement paste was calculated by Katz-Thompson equation and lattice Boltzmann method (LBM), respectively. Then, the calculated values were compared with those by gas permeability test. Results show that the tested gas permeability of cement paste is of 3.82×10^-18 m² to 7.29×10^-18 m². The Katz-Thompson equation only has the accuracy of order of magnitude and cannot accurately predict the permeability of cement paste. In contrast, the lattice Boltzmann method accurately predicts the intrinsic permeability of cement paste, 4.88×10^-19 m² to 15.48×10^-19 m², which is about 2 to 10 times smaller than the tested ones. This implies that the capillary pores in cement paste are still the main path of gas flow, whereas the air holes and micro cracks only locally improve the gas permeability.

Key words: gas permeability, 3D pore structure, cement paste, permeability prediction, lattice Boltzmann method