Influence of steel slag on mechanical properties and durability of concrete

Steel slag is a potential mineral admixture for concrete. In this paper, the influence of steel slag on the compressive strength, drying shrinkage, permeability to chloride, and carbonation resistance of concrete was investigated under two different conditions: constant W/B and constant 28 days’ compressive strength. The results show that under the condition of constant W/B, increasing the steel slag replacement tends to decrease the compressive strength (especially the early strength), increase the permeability, and decrease the anti-carbonation ability of concrete. The negative effect of steel slag on the compressive strength, permeability, and carbonation resistance of concrete is weaker at lower W/B. At high W/B, steel slag tends to accelerate the development of drying shrinkage at the early ages, but it has an insignificant influence on the ultimate shrinkage at 90 days. At low W/B, steel slag has little influence on the drying shrinkage of concrete. Under the condition of constant 28 days’ compressive strength, the concrete with steel slag exhibits lower early strength but higher late strength than the pure cement concrete. The concrete with steel slag can get permeability, drying shrinkage, and carbonation resistance similar to the pure cement concrete.