Study on mechanical properties and mechanism of CO2 mineralized blast furnace slag based material

To address the critical issues of massive solid waste accumulation and excessive greenhouse gas emissions, Carbon Sequestration Technology based on the Multi-solid waste collaborative utilization offers a solution by enabling effective carbon capture, utilization, and storage (CCUS) while processing the waste materials. This study selects Blast Furnace Slag as the primary raw material, with cement and Ca(OH) 2 and other material as activators, to develop a novel composite cementitious material based on a synergistic activation-carbonation mechanism. Employing experimental techniques including uniaxial compressive strength (UCS) testing, thermal gravimetric analysis (TGA), X-ray (XRD), and scanning electron microscopy (SEM), an in-depth analysis was conducted to investigate its mechanical properties, microstructure, phase composition, and CO 2 mineralization capacity.Research findings indicate that under curing periods of 3 and 7 days, the factors influencing the compressive strength of blast furnace slag based material solidified body rank in the following order: cement > Ca(OH) 2 > Na 2 SO 4 . Under different curing ages and carbonization time conditions, the optimal ratio of the solidified body is different.The dosage of admixture, curing age and carbonization time can effectively improve the UCS of solidified body, and the improvement of early UCS is the most significant, that is, when the cement content increases from 10 % to 15 %, The solidified body exhibited a strength increase of 84.8 %. When the content continues to increase to 20 %, it is only 12.8 %. With the fixed Ca(OH) 2 content at 3 %, increasing the cement content from 10 % (A-1) to 20 % (C-1) raised the 28-day CO 2 absorption rate from 24.1 mg/g to 32.1 mg/g, representing a 33.2 % increase.Analysis of the solidification mechanism reveals that the synergistic effect between hydration and mineralization reactions significantly enhances the efficiency of CO 2 utilization and sequestration. This study aims to provide a theoretical foundation and technical reference for employing blast furnace slag solid waste for CO 2 mineralization and storage.