Combined effect of supplementary cementitious materials and hot-dipped galvanized steel on performance of reinforced concretes subjected to chloride-induced corrosion

Concrete specimens with three types of cement (sulfate resistant high early strength – reference, pozzolanic, and with ground granulated blast furnace slag) reinforced with two types of steel (galvanized and carbon steel) were subjected to cycles of immersion in 1.0 M NaCl solution and drying at 40ºC. For each different steel-concrete condition, 6 rebars were tested. Experimental results show that galvanized steel presents longer corrosion initiation periods in concretes with supplementary cementitious materials. Particularly for pozzolanic concrete, this increased initiation period was 4.6 times longer on average, which reflects, in a similar way, on service-life simulations. In general, the average chloride thresholds of galvanized steel increased with a decrease in pore solution alkalinity. Compared to carbon steel, higher chloride thresholds were found for galvanized steel embedded in the lower alkalinity concrete matrix (calculated pore pH = 12.6). On the other hand, galvanized steel presented lower chloride thresholds for more alkaline pore pHs (pozzolanic and reference concretes). [Display omitted] •Decreasing pH led to higher chloride thresholds (CTH) for galvanized steel (GS).•Decreasing pH led to lower chloride thresholds (CTH) for carbon steel (CS).•Free CTH for GS in matrices with SCMs was between 18 % and 32 % higher than for CS.•SCMs delayed the corrosion initiation times, even more so for GS.•GS with pozzolanic concrete presented the longest corrosion initiation time.