Water Permeability of Cracked Cementitious Composites

Cracking is one of the most severe problems facing the concrete industry worldwide. Of critical importance is the drastic decline of durability associated with these cracks, and the resulting cost of repair or replacement of concrete structures. This research examines the effect of crack width and crack frequency upon the durability of reinforced mortar, quantified by water permeability. Crack widths tested range from 0mm (for uncracked mortar) up to 2.7mm. In addition to mortar, the durability performance of Engineered Cementitious Composites, or ECC, are also investigated in the cracked state. This high performance fiber reinforced cementitious composite exhibits closely spaced microcracks with inherently tight crack widths, typically less than 80 micron, even when strained up to 5% in uniaxial tension. The advantages of closely spaced microcracks over a small number of large cracks are investigated and discussed. Results show that even with a large number of closely spaced microcracks, the inherently small crack width of ECC material exhibits a water permeability close to that of uncracked concrete when strained up to 1.5% in uniaxial tension.