Development of carbon sequestration cement-based materials with mechanochemically carbonated carbide slag

Calcium carbide slag (CS) is a highly alkaline industrial byproduct with elevated calcium content. While CS demonstrates significant carbon sequestration potential, the inherent inertness of its carbonation product (calcite) limits its practical application in cement-based materials. In the present work, CS was mechanochemically treated with wet-grinding carbonation method. This approach achieved high-efficiency carbonation while overcoming the activity limitations of calcite product. Wet-grinding carbonation achieved 91.9% of theoretical CO 2 uptake within 15 minutes, reducing carbonation time by 25% compared to conventional bubbling carbonation method, under equivalent carbonation degree. Mechanochemical forces activated the carbonated CS by stripping inert CaCO 3 surface layers and exposing active sites, This process changed the inert characteristics of the calcite product, resulting in higher reactivity compared to the bubbling-carbonated CS. In addition, mechanochemical carbonation significantly reduces the particle size of CS, endowing it with dual effects of hydration induction and micro-filling. With incorporation of mechanochemically carbonated CS, the hydration induction period was shortened by 48.9% and the 28-day compressive strength was improved by 12%.