Resistance of Silica-Fume Concrete to Corrosion-Related Damage

Abstract

The effectiveness of silica-fume concrete in resisting damage caused by corrosion of embedded steel has been investigated using an accelerated impressed voltage-testing setup. The silica-fume concrete included 0, 10, 15, 20, and 25% silica as equal replacement of ordinary portland cement. Concrete samples were cured in either fresh water or 4% NaCl saline water for a 7- or 28-day curing period. Samples were saturated surface-dry at the beginning of the accelerated-corrosion testing to simulate actual conditions of superstructures. A susceptibility-to-corrosion (STC) index was calculated from test results. The setup and index have the potential of being used in a concrete-mix design approach that directly considers exposure to corrosive environments. The performance of silica-fume concrete in resisting damage caused by corrosion was improved. This improvement was optimal at a silica-fume dosage of 15%, and found to be several times better than the control mix. It was most significant at 28-day curing, when pozzolanic action had a chance to take place. Electrical resistivity was higher for silica-fume concrete, but alone could not characterize the concrete's resistance to corrosion damage.