The use of argon oxygen decarbonization slag (AODS) is restricted due to its volume unsoundness and low hydration reactivity. In this study, the feasibility of transforming AODS toward a highly reactive mineral admixture with appreciable CO2 sequestration was investigated, the hydration behavior, evolution of the compositions and microstructures of AODS with carbonation time were systematically studied, and CO2 footprint of carbonated AODS was elucidated. Results indicated that γ-C2S in AODS could quickly react with CO2 to form CaCO3. MgO and bredigite dissolved significantly when the pH value of the slurry dropped to 7.0, leading to a significant increase in the Mg2+ concentration of the slurry, and promoting the conversion of calcite to monohydrocalcite. However, due to the lower Ca/Si and Ca/Mg ratios, calcium silicate (CS) and akermanite exhibited extremely low carbonation reactivity. As the carbonation time increased, the particle size of CaCO3 gradually increased, from approximately 150 nm at 5min to approximately 400 nm at 20min, [SiO4] gradually transited from the Q0, Q1 and Q2 structures to the Q3 and Q4 structures, ultimately forming a large amount of amorphous SiO2 gel, which led to an obvious increase in specific surface area of AODS. The compressive strength of cement mortar mixed with 20 wt% carbonated AODS (CAODS) was increased by 25.8 % compared with that of the mortar incorporating AODS. The CO2 sequestration capacity of AODS can reach approximately 200 kg/t, and 193.4 kg CO2 can be cut when 1 ton of CAODS-based composite cement with excellent cementitious properties is produced.

中文翻译：

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将 AOD 炉渣转化为具有明显 CO2 封存能力的高活性矿物混合物：水化行为、微观结构演变和 CO2 足迹


氩氧脱碳渣 （AODS） 的使用因其体积不稳和低水合反应性而受到限制。在这项研究中，研究了将 AODS 转化为具有明显 CO2 封存的高活性矿物混合物的可行性，系统研究了 AODS 的水化行为、AODS 的组成和微观结构随碳化时间的演变，并阐明了碳酸 AODS 的 CO2 足迹。结果表明，AODS 中的 γ-C2S 可与 CO2 快速反应生成 CaCO3。当浆料的 pH 值降至 7.0 时，MgO 和 bredigite 显著溶解，导致浆料的 Mg2+ 浓度显著增加，并促进方解石向一氢方解石的转化。然而，由于 Ca/Si 和 Ca/Mg 比率较低，硅酸钙 （CS） 和刻骨干石表现出极低的碳化反应性。随着碳化时间的增加，CaCO3 的粒径逐渐增大，从 5 min 时的约 150 nm 增加到 20 min 时的约 400 nm，[SiO4] 逐渐从 Q0、Q1 和 Q2 结构转变为 Q3 和 Q4 结构，最终形成大量无定形的 SiO2 凝胶，导致 AODS 的比表面积明显增加。与掺入 AODS 的砂浆相比，掺入 20 wt% 碳酸 AODS （CAODS） 的水泥砂浆的抗压强度提高了 25.8 %。AODS 的 CO2 封存能力可达约 200 kg/t，生产 1 吨具有优异胶凝性能的 CAODS 基复合水泥时，可减少 193.4 kg CO2。