Study on the quantitative relationship between diffusivity and pore structure parameters of cement pastes

Abstract

This paper investigates the influence of pore structure on the chloride diffusivity of cement pastes. A quantitative relationship between pore structure parameters (i.e. pore diameter, porosity, constrictivity and tortuosity) and the diffusivity of cement paste is established. Microstructures of different pore structure parameters were generated, and then their diffusivities were predicted by a three-dimensional lattice diffusivity model. It was found that the pore diameter has little effect on the chloride diffusivity of cement paste, and the chloride diffusivity is significantly affected by porosity, constrictivity and tortuosity. The diffusivity is proportional to the porosity, proportional to the second order polynomial of the constrictivity and inversely proportional to the square of the tortuosity. The proposed model can provide a fundamental understanding for improving the diffusivity of cement-based composite materials.