Development of high-volume steel slag as cementitious material by ethylenediamine tetraacetic acid induced accelerated carbonation

Abstract

Steel slag, a by-product of primary steel production, is produced in large quantities and is primarily used as landfill or aggregate. Due to its high reactivity with CO2, steel slag can form calcium carbonate at room temperature and pressure, making it an ideal material for CO2 capture in the development of sustainable construction materials. Due to the transport properties of CO2 and carbonation kinetics, carbonation of steel slag is frequently carried out using pure gas under high pressure. In this study, ethylenediamine tetraacetic acid (EDTA)-induced accelerated carbonation was used to produce cement paste mixes consisting of up to 100% steel slag powder. Combination of cement and EDTA with steel slag proved to be effective in accelerating the carbonation reaction. EDTA increased the leaching of Ca from the steel slag, thereby enhancing the carbonation reaction, which was more obvious in longer durations (up to 28 days). The optimum cement paste mix (80% steel slag and 20% cement, with 0.1 mol/L EDTA solution) achieved maximum compressive strength of 14 MPa and CO2 uptake of 8.7% after 28 days of accelerated carbonation. Results demonstrated that the use of high-volume steel slag as a cementitious material has great potential in non-structural building applications.