Chloride-induced corrosion products of steel in cracked-concrete subjected to different loading conditions

This project focused on examining the composition and distribution of chloride-induced corrosion products at the rebar–concrete interfaces and on crack surfaces in reinforced ordinary Portland cement concrete (OPCC) and high performance concrete (HPC) subjected to different loading conditions. The results indicated that, regardless of the type of loading, there was a larger distribution of corrosion products along the rebar surface in the HPC than in the OPCC. Also, dynamic loading caused a greater detachment of the aggregate–paste bond in OPCC than static loading. The opening and closing of the cracks in salt solution under dynamic load forced corrosion products to flow from the rebar–concrete interface into the cracks in both OPCC and HPC. As a result, corrosion products diffused from the crack into the cement paste in the dynamically loaded OPCC but remained in the cracks in the dynamically loaded HPC, where they induced branched cracks. The mill-scale on the rebar was also evaluated before and after being embedded in concrete and was observed to be porous allowing ingress of species from the cement paste.