Corrosion Performance Evaluation of Rebar in Metakaolin Blended Concrete
Reinforcement corrosion is of obvious importance in reinforced structures in harsh environments. The presence of sulfates may influence the chloride-induced corrosion of rebar in concrete. In this paper, the results of an experimental investigation are presented wherein the influence of chloride and chloride plus sulfate ions on the corrosivity of rebar embedded in ordinary Portland cement (OPC) and OPC blended with metakaolin (MK) concretes has been investigated. In this investigation, concrete mixtures have been prepared with four replacement levels of OPC (0, 5, 10, and 15%) with MK and water to cementitious material ratio 0.5. Reinforced concrete specimens were exposed to pure chloride solution. Further, to investigate the influence of sulfate concentration on chloride-induced corrosion, the samples were exposed to the composite solution of chloride and sulfate ions of various concentrations. The corrosion performance of rebar has been monitored by the half-cell potential values. Besides, an impressed voltage technique for accelerated corrosion test has also adopted to investigate the optimum replacement level of cement with MK as a short-term technique. Results of accelerated corrosion test indicated that beyond 10% MK, the concrete was found to be less corrosion resistant. From potential measurements, it was observed that the presence of magnesium sulfate with chlorides influences the time to initiation of corrosion in both plain and MK blended concretes.
KeywordsImpressed voltage Corrosion Metakaolin Sulfates Chlorides
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