Steel slag, a byproduct of the steel industry, contains high amounts of f-CaO and f-MgO, which can cause soundness issues when used as binding materials or aggregates. Carbonation treatment is a reliable method to address this problem by transforming these phases into CaCO₃ and MgCO₃, respectively. This process not only reduces the expansive risk of steel slag but also captures and stores CO₂, reducing carbon emissions. The study reviews the physical and chemical properties of steel slag, the carbonation mechanism, factors affecting the carbonation process, and the potential applications of carbonated steel slag. The carbonation mechanism involves the reaction between CO₂ and f-CaO/f-MgO, forming CaCO₃/MgCO₃. Factors influencing the carbonation process include the chemical composition, mineral composition, and particle size of steel slag. The carbonation period, temperature, and CO₂ partial pressure also play significant roles. Carbonated steel slag can be used in various applications, such as bricks, supplementary cementitious materials, and aggregates, improving their mechanical properties and soundness. However, challenges remain, including variability in steel slag components, the need for further research on carbonation kinetics and thermodynamics, and balancing soundness with hydration activity.Steel slag, a byproduct of the steel industry, contains high amounts of f-CaO and f-MgO, which can cause soundness issues when used as binding materials or aggregates. Carbonation treatment is a reliable method to address this problem by transforming these phases into CaCO₃ and MgCO₃, respectively. This process not only reduces the expansive risk of steel slag but also captures and stores CO₂, reducing carbon emissions. The study reviews the physical and chemical properties of steel slag, the carbonation mechanism, factors affecting the carbonation process, and the potential applications of carbonated steel slag. The carbonation mechanism involves the reaction between CO₂ and f-CaO/f-MgO, forming CaCO₃/MgCO₃. Factors influencing the carbonation process include the chemical composition, mineral composition, and particle size of steel slag. The carbonation period, temperature, and CO₂ partial pressure also play significant roles. Carbonated steel slag can be used in various applications, such as bricks, supplementary cementitious materials, and aggregates, improving their mechanical properties and soundness. However, challenges remain, including variability in steel slag components, the need for further research on carbonation kinetics and thermodynamics, and balancing soundness with hydration activity.