The synergic effect of accelerated carbonation curing and cement replacement by calcium carbide residue (CCR) on the carbon sequestration potential and performance of concrete was examined. The concrete mixes included 0, 5, 10, and 20 % (by mass) CCR as partial cement replacement and were subjected to different initial air curing durations (0, 4, and 20 h) and subsequent carbonation curing durations (4 and 20 h). The performance was evaluated based on the CO uptake, 1-, 7-, and 28-day compressive strengths, and volume of permeable voids. Scanning electron microscopic (SEM) imaging was used to characterize the microstructure of the carbonated concrete. The environmental footprint of concrete produced herein was assessed. The experimental results showed that using CCR enhanced the CO uptake of concrete, with 5 and 10 % replacement levels providing superior outcomes in concrete subjected to 4- and 20-h carbonation curing. The compressive strength and a volume of permeable voids improved upon replacing cement with 5 % CCR. Such findings were validated by examining the void space in the SEM micrographs. Furthermore, prolonging the initial air curing and carbonation durations to 20 h each and incorporating 20 % CCR resulted in the highest CO uptake and lowest carbon footprint. Among the developed mixes, the most suitable was the mix subjected to 20 h of each initial air curing and carbonation curing with 20 % CCR replacement by mass. Nevertheless, all developed mixes satisfy the minimum strength requirement for concrete masonry unit applications.

中文翻译：

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掺有电石渣的混凝土的加速碳化养护

研究了加速碳化养护和电石残渣（CCR）替代水泥对混凝土碳封存潜力和性能的协同效应。混凝土混合物包含 0%、5%、10% 和 20%（按质量计）CCR 作为部分水泥替代品，并经历不同的初始空气养护时间（0、4 和 20 小时）以及随后的碳化养护时间（4 和 20 小时） ）。根据 CO 吸收量、1 天、7 天和 28 天的抗压强度以及可渗透空隙的体积来评估性能。使用扫描电子显微镜（SEM）成像来表征碳化混凝土的微观结构。评估了本文生产的混凝土的环境足迹。实验结果表明，使用 CCR 增强了混凝土的 CO 吸收量，5% 和 10% 的替代水平在经过 4 小时和 20 小时碳化养护的混凝土中提供了优异的结果。用 5% CCR 代替水泥后，抗压强度和渗透孔隙体积得到改善。这些发现通过检查 SEM 显微照片中的空隙空间得到了验证。此外，将初始空气固化和碳酸化持续时间分别延长至 20 小时并加入 20% CCR，可实现最高的二氧化碳吸收量和最低的碳足迹。在开发的混合物中，最合适的是经过 20 小时的初始空气固化和碳化固化（按质量计 20% CCR 替代）的混合物。尽管如此，所有开发的混合物都满足混凝土砌块应用的最低强度要求。