Water permeability of concrete with different crack widths was evaluated. The results
indicated that concrete permeability increased with crack width. The degree of the permeability
increase depended on the value of the crack opening in the concrete. When a
crack opening displacement was small, less than 50 microns under loading, the crack
opening had little effect on concrete permeability. With the crack opening displacement
increasing, from 50 to 200 microns, concrete permeability increased rapidly. When the
crack opening displacement was large, beyond 200 microns, the rate of increase of water
permeability became steady and less rapid.