Effect of various mixing properties of concrete on chloride penetration through cracks

Chloride penetration through cracks can threaten the durability of concrete substantially. Crack depth corresponded with critical crack width from the surface is a crucial factor in view of durability design of concrete structures. It is necessary to deal with chloride penetration through micro-cracks characterised with the features of concrete mixing. The purpose of this study is to identify and quantify the effect of the mixing features of concrete such as size of coarse aggregate, high strength and steel fibre reinforcement on chloride penetration through micro-cracks. In examining the effect of size of coarse aggregate on chloride penetration through cracks, the cracks should not impact on chloride penetration directly, although small size of coarse aggregate can lead to complicated micro-cracks in concrete. On the contrary, chloride should penetrate inwards through micro-cracks concentrated at the surface of coarse aggregates. In examining the effect of high strength concrete on chloride penetration through cracks, high strength concrete has an excellent performance to resist chloride penetration. If cracks are generated in high strength concrete, however, its performance is reduced up to the level of ordinary concrete. Finally, steel fibre reinforcement is effective to decrease chloride penetration through micro-cracks because of significant reduction of crack depth.