The effects of hydraulic pressure and crack width on water permeability of penetration crack-induced concrete

Cracks in concrete generally interconnect flow paths and increase the permeability of concrete. The increase of permeability due to gradual crack growth allows more water or aggressive chemical ions to penetrate the concrete and facilitate deterioration. This research aims to study water permeability and how it is affected by hydraulic pressure and crack widths in cracked concrete. Tests were carried out as a function of hydraulic pressure and crack width, using the splitting and reuniting method to manufacture concrete specimens with controlled crack widths. Crack widths were examined using a microscope. The results showed a considerable increase in water transport as crack width and hydraulic pressure increased. But when the crack width was smaller than 50 mu m, it had little effect on concrete permeability. Due to autogenous healing, the water flow through such cracks was gradually reduced over time. However, when the crack width was between 50 and 100 mu m and hydraulic pressure was greater than 0.025 MPa, concrete permeability increased rapidly. (C) 2010 Elsevier Ltd. All rights reserved.