通过测试单独掺入液体无碱速凝组分硫酸铝和氟化铝后水泥浆的凝结时间以及对掺速凝组分后达到终凝、水化1 d及水化7 d 的水泥浆体进行XRD图谱分析，深入探讨液体无碱速凝剂组分硫酸铝和氟化铝对水泥的速凝机理。试验结果表明： 硅酸盐水泥中掺入硫酸铝溶液因生成大量的钙矾石，同时因消耗大量的钙离子及水化热的作用促进C3S的水化作用导致浆体快速凝结；氟化铝溶液主要通过形成C3AH6 而导致水泥浆体速凝，氟化铝溶液中铝离子对水泥水化起速凝作用，而氟离子起缓凝作用。

The acceleration mechanism of liquid alkalifree accelerating components, including aluminum sulfate and aluminum fluoride, is discussed by testing on the setting time of cement paste mixed with aluminum sulfate and aluminum fluoride respectively, as well as by XRD analysis on the cement paste mixed with accelerating components after final setting, 1day hydration and 7day hydration. The study results show that, due to the large amount of ettringite generated and the C3S hydration caused by calcium ion reduction and hydration heat, the setting of the cement paste is accelerated when aluminum sulfate solution is mixed into the Portland cement; due to the C3AH6 generated, the setting of the cement paste is accelerated by aluminum fluoride solution; the aluminum ion in the aluminum fluoride solution accelerates the hydration of the cement paste; the fluoride ion in the aluminum fluoride solution retards the setting of the cement paste. The paper can provide a theoretical basis for developing and promoting the application of highperformance liquid alkalifree accelerator.