Effectiveness of corrosion inhibiting admixture combinations in structural concrete

A long-term corrosion study was conducted to determine the effectiveness of calcium nitrite, silica fume, fly ash, ground granulated blast furnace slag, and DSS in reducing corrosion of reinforcing steel in concrete. Mixture proportions included single, double, and triple combinations of these admixtures. Non-cracked and pre-cracked slab specimens were evaluated by visual inspections, macrocell readings, half-cell potentials, and autopsies. Triple combinations of calcium nitrite, silica fume, and either fly ash or ground granulated blast furnace slag, as well as a double combination of calcium nitrite and ground granulated blast furnace slag, performed very well and are recommended in concrete mixtures exposed to severe corrosive environments. DSS outperformed the other admixtures for corrosion prevention in this study; however, it resulted in somewhat lower compressive strengths and had not been fully tested for effects on other concrete properties.