摘   要：为快速分析和判断混凝土不凝结原因，研究了缓凝剂（葡萄糖酸钠）的超掺、粉煤灰、矿渣粉完全替代水泥对20 h龄期混凝土溶液pH值的影响以及在缓凝剂超掺情况下采用火焰光度计检测稀释液中Na元素浓度变化。结果表明，缓凝剂超掺对混凝土pH值无显著影响；粉煤灰、矿渣粉完全替代水泥时pH值有显著差异；混凝土溶液中Na元素火焰光度计法的检测浓度与缓凝剂超掺倍数成线性正相关，可以通过混凝土溶液Na检测浓度推测缓凝剂超掺倍数。本论文提出了一种快速判断混凝土不凝结原因的方法，可供工程各相关方参考。

Abstract: The pH of the solution in concrete at the age of 20 h was studied when cement was completely replaced by fly ash, slag powder and the dosage of retarder(sodium gluconate) was mixed excessively for rapid analysis and judgement of the cause of concrete non condensation. The flame photometer was used to measure the concentration of Na element under the condition of overdoge addition of retarder. The results show that the change of pH in concrete with the excessive dosage of retarder is not obvious. When cement is completely replaced by fly ash and slag powder, pH of the concrete has significant difference. The concentrion of Na element measured by flame photometer has a linear positive correlation with the super multiplier of retarder and the super multiplier of retarder can be deduced from the concentration of Na element. A fast method to determine the cause of concrete not condensing is put forward for reference by relevant parties in the project.