Low curing temperature conditions (5–15 °C) in cold regions pose major challenges for soil improvement using conventional binders, underscoring the urgent need for solutions to enhance soil strength and ensure engineering safety. This study investigated the feasibility and temperature-dependent behaviors of bio‑carbonation of reactive magnesia (BCRM) technology for soil improvement in cold regions. Unconfined compressive strength tests were conducted to explore the effects of curing temperature (T) and curing age (t) on strength enhancement. Combined with macro- (water content and dry density) and micro- (mineral composition and microstructure) analysis, the underlying mechanisms were elucidated. Experimental results showed that low T retarded the bio‑carbonation reaction of reactive magnesia, resulting in longer t required to obtain stable ultimate strength. However, despite lower increase rates, bio‑carbonized samples achieved higher ultimate strength and secant modulus at lower T. It was primarily attributed to the preferential formation of hydrated magnesia carbonates with higher content and crystallinity at low T, which enhanced the bridging and bonding performance. Comparative analyses with ordinary Portland cement (OPC) highlighted the superior efficiency of BCRM technology in stabilizing soil at low T, showing higher ultimate strength and shorter curing age. Notably at 5 °C, the ultimate strength of the bio‑carbonized sample cured for 12 days was up to 2.94 times that of the OPC-reinforced sample cured for 28 days. This study provides an efficient solution for soil improvement in low-temperature conditions. It is expected to enhance soil stability and hold significant implications for preventing and mitigating geological and geotechnical risks associated with soil deterioration in cold region engineering.

中文翻译：

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一种采用活性氧化镁生物碳化的高效生物稳定技术，用于寒冷地区的土壤改良


寒冷地区的低固化温度条件 （5–15 °C） 对使用传统粘合剂的土壤改良构成了重大挑战，凸显了迫切需要提高土壤强度和确保工程安全的解决方案。本研究调查了活性镁砂生物碳化 （BCRM） 技术在寒冷地区土壤改良中的可行性和温度依赖性行为。进行无侧限抗压强度试验，探讨固化温度 （T） 和固化年龄 （t） 对强度增强的影响。结合宏观 （含水量和干密度） 和微观 （矿物成分和微观结构） 分析，阐明了其潜在机制。实验结果表明，低 T 延缓了活性氧化镁的生物碳化反应，导致需要更长的 t 才能获得稳定的极限强度。然而，尽管增加速率较低，但生物碳化样品在较低 T 下实现了更高的极限强度和割线模量。这主要归因于在低 T 下优先形成具有较高含量和结晶度的水合碳酸镁，从而增强了桥接和粘合性能。与普通波特兰水泥 （OPC） 的比较分析突出了 BCRM 技术在低 T 稳定土壤方面的卓越效率，显示出更高的极限强度和更短的固化年龄。值得注意的是，在 5 °C 时，固化 12 天的生物碳化样品的极限强度是固化 28 天的 OPC 增强样品的 2.94 倍。本研究为低温条件下的土壤改良提供了一种有效的解决方案。 预计它将提高土壤稳定性，并对预防和减轻与寒冷地区工程中土壤恶化相关的地质和岩土工程风险具有重要意义。