The widespread use of ordinary Portland cement (OPC), which has a significant carbon footprint, greatly contributes to the climate crisis. High belite cement (HBC) is renowned for its low-carbon characteristics, resulting in an evident reduction in both energy consumption and CO emissions. Fly ash (FA), an industrial solid waste material, is commonly employed in the construction of mass concrete structures. This combination facilitates the adoption of cleaner and more ecologically sustainable construction manufacturing processes. The durability of structures constructed from HBC and FA has not been fully demonstrated due to their exposure to constantly changing atmospheric conditions. In order to unravel this issue, a comparative investigation was carried out through laboratory acceleration testing, aiming to evaluate the macro- and micro-mechanical properties, chemical compositions, and micro-morphology of HBC and OPC with FA under a rapid temperature changing cycle (RTC) within 5–45°C. The findings reveal the mechanism of deterioration under RTC, including the phase transformation of C–S–H, the propagation of micro-cracks, the coarsening of the pore structure, and the loss of toughness. FA alleviates the reduction in toughness, but also undermines the mechanical properties. Additionally, it was noted to undergo pozzolanic reaction, residual hydration and carbonation during RTC. Regarding OPC, the inclusion of FA within a specific dosage range (0–30%) has a beneficial impact on compressive strength. However, as for HBC, the presence of FA entirely exhibits a detrimental effect on service performance.

中文翻译：

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评估掺有粉煤灰的高贝利特水泥在长期温度变化下的耐久性能


普通波特兰水泥（OPC）的广泛使用具有显着的碳足迹，极大地加剧了气候危机。高贝利特水泥（HBC）以其低碳特性而闻名，可明显减少能源消耗和二氧化碳排放。粉煤灰 (FA) 是一种工业固体废料，通常用于大体积混凝土结构的施工。这种组合有助于采用更清洁、更生态可持续的建筑制造工艺。由 HBC 和 FA 建造的结构的耐久性尚未得到充分证明，因为它们暴露在不断变化的大气条件下。为了解决这个问题，通过实验室加速测试进行了比较研究，旨在评估 HBC 和 OPC 与 FA 在快速温度变化循环下的宏观和微观机械性能、化学成分和微观形貌（ RTC）在 5–45°C 范围内。研究结果揭示了RTC下的劣化机制，包括C-S-H相变、微裂纹扩展、孔结构粗化和韧性损失。 FA缓解了韧性的降低，但也损害了机械性能。此外，还注意到在 RTC 期间会发生火山灰反应、残余水化和碳酸化。对于 OPC，在特定剂量范围 (0–30%) 内添加 FA 对抗压强度具有有益影响。然而，对于 HBC 来说，FA 的存在完全对服务性能产生了不利影响。