Improving mechanical behavior and microstructure of concrete by using BOF steel slag aggregate

Abstract As an industrial by-product of steel manufacturing, steel slag would cause severe farmland occupation, water pollution and other environmental issues. It can be further categorized into basic oxygen furnace (BOF), electric arc furnace and ladle furnace slags, in which BOF steel slag (BOFSS) accounts for nearly 70% of the total steel slag production in mainland China. Therefore, massive consumption of BOFSS in reasonable fields is of unprecedented significance for resource recycling and environmental conservation. In this paper, BOFSS was adopted to replace coarse and fine aggregates of ordinary concrete to produce “Greener” concrete. A total of 15 concrete mixes with different replacement ratios of coarse and fine aggregates using BOFSS were designed, the mechanical property and microstructure (mercury intrusion porosimetry and scanning electron microscope tests) of which were studied. Results revealed that the optimum replacement ratios of coarse and fine aggregates were 50% and 30%, respectively. With these ratios, the later-age compressive strength and microstructure of concrete could be significantly improved. Therefore, it is concluded that the use of BOFSS in concrete not only benefits the environmental protection and material greenness, but also improves the behavior of concrete, which provides a win-win solution.