Effect of Partial replacement of Portland cement with micro- silica on mechanical characteristics of concrete and corrosion behavior of mild steel in 1M HCl

摘要

The effect of micro-silica (MS) as Portland cement (PC) replacement on corrosion resistance of mildsteel rebar were considered by open circuit potential (OCP), electrochemical impedance spectroscopy(EIS) and water absorption analysis after exposure to 1M HCl solution. Compressive strength testswere done to investigate the mechanical property of the concrete samples. By increasing immersiontime, all concrete samples containing MS indicated a reduction in water absorption value compared tothe concrete sample without MS. The samples with 8 wt% MS exhibited the highest compressivestrength after 8 weeks exposure time in a 1M HCl solution. The value of OCP for the steel reinforcedconcrete specimens with 8 wt% MS remained in the uncertain or low corrosion zone during theprocess. The EIS results showed that the 8 wt% MS sample had a higher the concrete resistance andcharge-transfer resistance compared to other samples, showing lower porosity of concrete structure andthus more improvement in corrosion resistance of the mild steel surface. The SEM images of mild steelrebars revealed that the steel reinforced concrete with 8 wt% MS content had low corrosion andminimum pit products, indicating the slight pitting corrosion shaped on the surface of mild steel rebar,which was in agreement with the results obtained from electrochemical study.