Rebar Corrosion in MgSO4 Solution

Abstract

Chloride ion attack is known to be the major cause of reinforcing steel corrosion in concrete. This study aims to demonstrate that not only chloride ions but also sulfate ions corrode the reinforcing steel embedded in concrete. Reinforced concrete specimens are prepared with different water‐cement ratios of 0.40, 0.55, and 0.70. A single piece of reinforcing steel is centrally embedded in the specimens at a clear concrete cover of 31 mm (1.25 in.). The reinforced concrete specimens are immersed in a 5% ${\mathrm{MgSO}}_4$ solution and subjected to corrosion monitoring for a period of 43 months. Half‐cell potential and linear polarization resistance techniques are used for corrosion monitoring. The test results indicate that the sulfate ions are corrosive to reinforcing steel, but their severity is less than that of chloride ions. The reduction in the alkalinity of concrete due to a reaction between sulfate salts and calcium hydroxide of the hydrated cement paste is believed to be responsible for the sulfate‐induced reinforcing steel corrosion.