Influence of iron mill scale additive on the physico-mechanical properties and chloride penetration resistance of concrete

Reinforced concrete structures are normally exposed to various aggressive environmental conditions; thus it is essential to protect the steel reinforcement from corrosion and the concrete from degradation. This experimental study is aimed at optimising the physico-mechanical properties of reinforced concrete by using iron mill scale as a replacement for cement. Reinforced cement mortars and concrete specimens with and without the addition of iron mill scale were partially immersed in 3·5% w/w sodium chloride solution for 17 months and 130 d, respectively. The mill scale was added to the aforementioned cementitious composites in proportions of 5% and 10% by weight of cement. Its effect on chloride penetration resistance was evaluated using various standardised and non-standardised experimental techniques. The results showed that the additive increased the resistance of reinforced cementitious composites to chloride penetration, reduced the corrosion of steel reinforcement and improved the compressive strength of concrete. Furthermore, iron mill scale decreased the concentration of chloride ions in cement mortars which were partially immersed in sodium chloride solution.