Alkali activation of metallurgical slags produces low-carbon cementitious binders for sustainable concrete production. However, the potential deleterious reaction of internal alkalis in alkali-activated slag (AAS) with siliceous aggregates is a serious durability concern. In this work, the alkali–silica reaction (ASR) in alkali-activated ground granulated blast furnace slag mortars with various activator dosages and types, aggregate reactivity, as well as incorporation of pulverized fly ash or silica fume is studied. The ASR-induced length expansion and microstructural damage in AAS mortars are studied by a modified accelerated mortar bar test and scanning electron microscopy with X-ray energy-dispersive spectroscopy. The results show that the kinetics of ASR-induced damage, as well as the gel composition and spatial distribution, in AAS mortars is highly dependent on the alkali dosage, activator type, and aggregate reactivity. The ASR-induced length expansion is approximately proportional to the volumetric fraction of dissolved glassy aggregates. However, AAS mortars show noticeable autogenous shrinkage at the initial stage of immersion, making the conventional judgment of ASR risks using length expansion as the sole indicator invalid. The dissolution kinetics of aggregate, which is influenced by the level of alkalinity and availability of reactive silica, seems to be the rate-limiting reaction of ASR-induced damage in AAS mortars under accelerated testing conditions.

中文翻译：

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影响碱活化渣砂浆中碱-二氧化硅反应动力学和凝胶组成的因素

冶金炉渣的碱活化生产低碳水泥粘合剂，用于可持续混凝土生产。然而，碱活化炉渣 (AAS) 中的内碱与硅质骨料的潜在有害反应是一个严重的耐久性问题。在这项工作中，研究了不同活化剂剂量和类型、骨料反应性以及粉煤灰或硅粉掺入的碱活化磨粒高炉矿渣砂浆中的碱-二氧化硅反应 (ASR)。通过改进的加速砂浆棒试验和具有 X 射线能量色散光谱的扫描电子显微镜研究 ASR 引起的 AAS 砂浆中的长度膨胀和微观结构损伤。结果表明，ASR 诱导损伤的动力学，以及凝胶组成和空间分布，AAS 砂浆在很大程度上取决于碱用量、活化剂类型和骨料反应性。ASR 引起的长度膨胀与溶解的玻璃状聚集体的体积分数大致成正比。然而，AAS砂浆在浸泡初期表现出明显的自收缩，使得传统的以长度膨胀为唯一指标的ASR风险判断无效。集料的溶解动力学受碱性水平和活性二氧化硅的可用性影响，似乎是加速测试条件下 ASR 砂浆中 ASR 引起的损坏的限速反应。然而，AAS砂浆在浸泡初期表现出明显的自收缩，使得传统的以长度膨胀为唯一指标的ASR风险判断无效。集料的溶解动力学受碱性水平和活性二氧化硅的可用性影响，似乎是加速测试条件下 ASR 砂浆中 ASR 引起的损坏的限速反应。然而，AAS砂浆在浸泡初期表现出明显的自收缩，使得传统的以长度膨胀为唯一指标的ASR风险判断无效。集料的溶解动力学受碱性水平和活性二氧化硅的可用性影响，似乎是加速测试条件下 ASR 砂浆中 ASR 引起的损坏的限速反应。