Abstract Little published data is available to guide specification calcium sulfoaluminate cement (CSA) mixtures with citric acid retarder dosage rates capable of achieving adequate field working times, nor to understand the effect of retarder dosage on hydration and property development, representing a significant barrier to widespread CSA concrete use. Thus, this study investigated the use of citric acid with two commercially-available CSA cements, tracking the effects of dosage on phase development, hydration, setting, and compressive strengths. Key findings were that: citric acid successfully retarded initial set past 120 min for both cements despite significantly different chemistries; increasing cement anhydrite content reduced retarder effectiveness and altered hardened binder microstructure, reducing compressive strengths; greater retarder dosages did not negatively affect cumulative hydration, nor strengths; and the time at which the maximum rate of heat evolution occurred correlated with final setting, a relationship useful for predicting field mixture behavior based on laboratory testing.

中文翻译：

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缓凝剂对硫铝酸钙水泥水化及性能发展的影响

摘要 很少有已发表的数据可用于指导规范硫铝酸钙水泥 (CSA) 混合物与能够实现足够的现场工作时间的柠檬酸缓凝剂剂量率，也没有了解缓凝剂剂量对水化和性能发展的影响，这代表了广泛应用的重大障碍。 CSA混凝土使用。因此，本研究调查了柠檬酸与两种市售 CSA 水泥的使用，跟踪剂量对相发展、水化、凝固和抗压强度的影响。主要发现是： 柠檬酸成功地延缓了两种水泥的初始凝固超过 120 分钟，尽管化学性质明显不同；增加水泥硬石膏含量会降低缓凝剂的有效性并改变硬化的粘合剂微观结构，从而降低抗压强度；更大的缓凝剂剂量不会对累积水合作用产生负面影响，也不会影响强度；最大放热速率发生的时间与最终凝结相关，这种关系可用于根据实验室测试预测现场混合行为。