Control of Macro-Cell and Micro-Cell Corrosion of Steel In Cracked Concrete

Abstract

A scientific investigation on controlling macrocell and microcell corrosion of steel bars in cracked concrete made with slag cement types B (SC-B) and slag cement type C (SC-C) was performed for a total of seven cases. Two control cases, one for SC-B and another one for SC C were also investigated. Cement and lime-coated steel bars were used to control corrosion, along with the injection of lime slurry into the cracked region. Prism specimens were made for each of the cases. The prism specimens were made using a segmented steel bar that allowed for an external electrical connection. This connection was required for measuring the macro cell and micro-cell corrosion currents. For the first 30 days, the specimens were submerged in seawater and continuously exposed to it. After that, the specimens were subjected to five cycles of submerging followed by drying at two-day intervals. Throughout this time, a data logger was used to record and monitor the voltage drop. Half-cell potential and depth of the corrosion were also studied. The experimental results show that when submerged in seawater, SC-C cement concrete outperforms SC-B cement concrete in terms of corrosion resistance. Lime treatment decreases corrosion current and improves corrosion resistance in SC-B cement concrete and SC-C cement concrete. Steel bars coated in lime and cement performed better than the uncoated steel bars of SC-B. The most efficient approach for avoiding corrosion is to treat SC-C cement concrete with lime slurry before immersing it in seawater.