This investigation examines the impact of different CO2 curing concentrations on the mechanical and microstructural properties of recycled concrete aggregates, aiming to optimize the carbonation process for enhanced practicality. Utilizing 25 recycled concrete samples, the study varied CO2 concentrations (20 %, 40 %, 50 %, 60 %, and 95 %) and pre-conservation durations (24–120 h), conducting tests for carbon sequestration, compressive strength, and splitting tensile strength to determine the effects on recycled concrete's performance. Key findings reveal a direct correlation between increased CO2 curing concentrations and carbon sequestration levels, with an observed pattern of initial increase followed by a plateau or decrease in sequestration with extended pre-conditioning. Interestingly, while compressive strength generally improved with higher CO2 concentrations, splitting tensile strength showed a decrease, suggesting different impacts of CO2 concentration on various mechanical properties. A notable observation was that at 60 % CO2 concentration, compressive strength was slightly lower (by 2.46 %) compared to the 95 % concentration, yet the splitting tensile strength was 2.84 % higher at 60 %, indicating that a 60 % CO2 curing concentration might offer an optimal balance between economic efficiency and material performance enhancement. This balance suggests significant improvements in resource utilization compared to traditional pure CO2 curing methods. In conclusion, this study provides substantial evidence supporting the optimization of CO2 curing for recycled concrete, advocating for a 60 % concentration as the most effective strategy to enhance both the environmental sustainability and the mechanical performance of recycled aggregates. These insights significantly contribute to advancing low-carbon and sustainable practices within the construction industry.

中文翻译：

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研究碳化养护浓度对再生混凝土力学性能和微观结构的影响


本研究探讨了不同二氧化碳养护浓度对再生混凝土骨料机械和微观结构性能的影响，旨在优化碳化过程以增强实用性。该研究利用 25 个再生混凝土样品，改变二氧化碳浓度（20%、40%、50%、60% 和 95%）和预保存时间（24-120 小时），进行碳封存、抗压强度和劈裂拉伸强度以确定对再生混凝土性能的影响。主要发现揭示了二氧化碳固化浓度增加与碳封存水平之间存在直接相关性，观察到的模式是最初增加，然后随着预处理的延长，封存量趋于稳定或减少。有趣的是，虽然压缩强度通常随着二氧化碳浓度的升高而提高，但劈裂拉伸强度却下降，这表明二氧​​化碳浓度对各种机械性能的影响不同。值得注意的是，在 60% CO2 浓度下，与 95% 浓度相比，抗压强度略低（降低了 2.46%），但在 60% 浓度下，劈裂拉伸强度却高出 2.84%，这表明 60% CO2 固化浓度可能会降低在经济效益和材料性能增强之间提供最佳平衡。这种平衡表明与传统的纯二氧化碳固化方法相比，资源利用率显着提高。总之，本研究提供了支持优化再生混凝土二氧化碳固化的充分证据，主张将 60% 的浓度作为增强环境可持续性和再生骨料机械性能的最有效策略。 这些见解对推进建筑行业的低碳和可持续实践做出了重大贡献。