Influence of mineral admixtures on the mechanical properties and corrosion of steel embedded in high strength concrete

摘要

The corrosion rate of steel material in concrete is extremely low when the metal is in passive state at normal conditions. This situation is completely different in the regions where corrosive ions are available. Chlorine ions around steel, at the passive state, destroy the reinforced concrete. To improve the mechanical properties of concrete and to increase the corrosion resistance of steel embedded in concrete, silica fume (SF) and blast furnace slag (BFS) were used at different ratio instead of Portland cement (PC). The dry-unit weight, the compressive strength and the ultrasonic pulse velocity (UPV) of the samples without steel reinforcement were determined. The corrosion current densities of the samples with steel reinforcement in 5% NaCl solution were measured by the linear polarization technique on the 28th, 75th, 150th and 250th days. Finally, it was observed that the samples with 10% SF + 20% BFS had the highest compressive strength, and that the concrete samples with 10% SF + 40% BFS and 0.35 water-binder ratios had the lowest corrosion current density. As a result, it can be concluded that the mineral admixtures improved the compressive strength, UPV and corrosion current density.