Study on the treatment of BOF slag to replace fine aggregate in concrete

Excessive free lime in the BOF slag will react with water and causes serious expansion, and thus, results in its reutilization difficulty. In this study, scrubbing attrition and chelating reagent treatment were used to remove free lime from BOF slag. After removing free lime, the BOF slag was used as fine aggregate for making cement mortar. Under different curing periods, the specimens were characterized for their physical and mechanical properties, ultrasound conduction velocity, and volume expansion. By reducing free-calcium oxide through attrition and chelating processes, the expansion rate of specimen can be reduced to 0.16%. The compressive strength and flexural strength of cement mortars prepared with BOF slag can reach 45.4 MPa and 7.1 MPa, respectively. The test results suggested that the scrubbing and chelating treatments can effectively remove free-calcium oxide and improve expansion and strength development of concrete mortar.