Sensitivity analysis for binders in concrete mix to the corrosion risk of steel embedment in chloride-bearing environments

Abstract

The sensitivity to corrosion-free life in concrete structures exposed to chlorides was evaluated with respect to different binder in mix. As binders, ordinary Portland cement (OPC), ground granulated blast furnace slag (GGBS), pulverised fuel ash (PFA) and silica fume (SF) were selected. Prior to the sensitivity analysis, experimental works were performed to achieve control values for the apparent diffusion coefficient, surface chloride concentration and critical chloride threshold level for corrosion. The cover depth was set 100 mm in the sensitivity analysis. The margin for the variation in parametric values was set −50 to +100% to the control. As a result, OPC had the highest sensitivity for the chloride threshold level and surface chloride concentration to corrosion-free life, whilst these sensitivities in other mixes were lower in a similar range between them. Either a double of the chloride threshold level or half of the surface chloride in OPC mix could produce the corrosion-free life in an equated range for 65% GGBS mix at an equivalent condition. As for cover depth and apparent diffusion coefficient, their sensitivity to corrosion-free life was independent to binder type, which nevertheless affects the corrosiveness.