Durability of Fly Ash Added Reinforced Concrete in Chloride and Composite Chloride–Sulfate Environment

Abstract

This work reports the corrosion performance of steel reinforcement in OPC and OPC with 20% fly ash concrete mixes exposed to chloride (5% NaCl) and composite chloride–sulfate solutions (5% NaCl + 2% MgSO4 and 5% NaCl + 4% MgSO4). The reinforced concrete specimens were exposed to these solutions for a period of 12 months with alternate wetting–drying cycles. Compressive strength and corrosion parameters were measured on concrete cube specimens and reinforced concrete specimens, respectively. The half-cell potential test and linear polarization resistance measurement (LPR) were performed to evaluate the corrosion parameters of steel reinforcement. From the results, it is observed that the compressive strength of the OPC concrete mix was higher as compared to OPC with 20% fly ash. From the results of corrosion parameters, it is observed that the addition of magnesium sulfate in composite solutions reduced the probability of occurrence of steel reinforcement corrosion and corrosion current density till the exposure period of 12 months. The replacement of the OPC with fly ash improved the performance of concrete mix against corrosion of steel reinforcement. Further, mostly there was less probability of occurrence of steel reinforcement corrosion and lower corrosion current density at lower w/b ratio as compared to that at higher w/b ratio.