CORROSION OF STEEL IN MSE WALLS DUE TO DEICERS AND BACKFILL AGGREGATES

Corrosion of the reinforced steel is the main cause that afflicts the long-term performance of mechanically stabilized earth (MSE) walls. The deicing salts used on pavements to melt down snow is one of the major reasons of corrosion of these reinforced steels. The aggressiveness of deicers in terms of corrosion of reinforced steel was estimated through the potentiodynamic polarization technique at various concentrations of deicers. The present study aims to determine the corrosion behavior on bare steel in presence of various individual deicing salt or deicers e.g., sodium chloride, calcium chloride, magnesium chloride and potassium acetate at various concentration i.e., 0.25, 0.50 and 1.00 M. In addition, the corrosivity of two backfill aggregates i.e., natural aggregate and recycled concrete aggregate, was compared. The results show that the corrosion effect of deicers on reinforced steel of MSE wall depends on its chemical composition and concentration. Among the deicers used, the sodium chloride was most aggressive and potassium acetate is the least aggressive for the bare steel. The pH and electrical resistivity values of the natural and recycled concrete aggregates were compared with the standards provided by American Association of State Highway and Transportation Officials and found to be non-corrosive. The corrosion rate of both the aggregates on bare steel were inappreciable and while analyzing the corrosiveness of these two aggregates, recycled concrete aggregate sample was observed to be more aggressive than the natural aggregate.