Carbonation hardening of EAF slag-based binders using CO2 under low and supercritical pressure conditions

This study investigates the influence of CO2 pressure regimes on the carbonation hardening of electric arc furnace (EAF) slag binders. Ten specimens were produced using statically compacted EAF slag with 8 wt% water ad. The specimens were then divided into two groups, each subjected to a different CO2 curing regime: accelerated curing (ACC) and supercritical curing (SCC). Samples were evaluated through compressive strength tests, TGA, XRD, SEM-EDX, and MIP analyses. The results demonstrated that supercritical curing (SCC) produced a more homogenous carbonation, a greater decrease in porosity, and improved mechanical properties. Thus, this study highlights the benefits of using supercritical curing to achieve higher mechanical properties due to more homogeneous curing across the samples' entire volume. Additionally, the EAF slag binders exhibited favourable binding properties without strict control of particle size distribution, facilitating application in the construction sector while contributing to waste circularity by reducing landfill disposal of EAFS and supporting the development of waste circularity and CO2 sequestration through mineralisation in carbonated materials.