Chloride-Induced Corrosion of Steel in Cracked OPC and PPC Concretes: Experimental Study

The corrosion behavior of steel in cracked ordinary portland cement (OPC) and portland pozzolana cement (PPC) concretes when exposed to a chloride-rich environment is presented here. Three water-to-cement (w/c) ratios, and precrack widths of 0.2 and 0.4 mm were studied. A simple U-shaped specimen with precracks under flexural load was used in the study; the specimen has a deformed steel bar of 12 mm diameter placed at the bottom with 20 mm clear cover. Measurements made include chloride ion penetrability, sorptivity, half-cell potential, resistivity, total charge passed and gravimetric weight loss. The chloride ion penetrability of PPC was found to be nearly three times lower than that of OPC. The reduction in the gravimetric weight loss of rebars in PPC with respect to those in OPC is in the range of about 1.5 to 2.0 in the case of precracked concretes. The reduction in diameter (i.e., caused by pitting) is higher for OPCs. Studies showed that PPC is significantly superior to the corresponding uncracked OPCs in terms of corrosion inhibition even under cracked conditions.