Evaluation of steel slags in CO2 sequestration and as supplementary cementitious material

This work presents the results of enforced carbonation experiments realised on steel slags, sourced from various European plants and proposes carbonation as a viable valorization method. All samples demonstrated rapid carbonation reactions and effectively sequestered substantial amounts of CO 2 . Calcite and silica gel were identified as the main reaction products. The mineralogical and chemical compositions of the slags played a crucial role in influencing the carbonation process. This transformation altered the slags' properties, converting them from latent hydraulic materials into pozzolanic supplementary cementitious materials. However, carbonation alone did not significantly enhance composite cement performance. To optimize the cement composition, the addition of calcium sulphate, hydration accelerators, or a combination of both, depending on the characteristics of the slag used, was necessary. • Evaluation of carbonation performance of steel slag in mild condition. • Replacement of 40 % of cement with untreated and carbonated slag in mortar mixes. • Evaluation of carbonation benefits in mechanical performance. • Hydration kinetics study by portlandite blends with studied samples.