Experimental Investigation on Transport Properties of Cement-Based Materials Incorporating 2D Crack Networks

This paper investigates the correlation between the geometry of crack networks and the altered transport properties of cement-based porous materials. Cracks were artificially introduced into slice specimens to obtain bidimensional (2D) crack networks, and the network was characterized by the crack density, orientation, connectivity and crack opening aperture. For the permeability, the water vapor sorption isotherms were measured and an algorithm was established to solve the intrinsic permeability of cracked specimens with the help of moisture transport modeling and the data of drying tests. The electrical conductivity of cracked specimens was measured using an alternative current method. The study on the specimens with percolated cracks shows that: (1) the pertinent geometry parameters for altered transport properties include average-based crack density, crack opening and local crack connectivity; (2) the water permeability of cracked specimens is correlated to the combination (b^{1.7}rho f) and electrical conductivity to (b^{0.45}rho f); (3) the different exponents on the crack opening/length ratio reflect the resistance of tortuosity of crack paths to the water and current flow and this resistance is stronger for current flow.