通过测定掺KH聚羧酸减水剂的化学收缩、初期水化热及电性能，并结合XRD，TG－DSC分析，研究了KH聚羧酸减水剂的缓凝机理。结果表明：聚羧酸减水剂可以有效抑制化学收缩，1 d化学收缩减小20%以上，28 d化学收缩减小30％以上；有较强的缓凝作用，有效抑制水化放热，延缓结构形成；凭借其分子结构中的羟基（-OH）、羧基（-COO-）、磺酸基（-SO3-）、聚乙氧基（-OCH2CH2-）等官能团，通过吸附、络合、静电斥力及空间位阻的作用，有效抑制初期C3A和C3S水化，而不影响后期结构发展。

By means of researching on chemical shrinkage, heat of hydration and electrical properties of the initial structure, and using the XRD, TG DSC, the retarding mechanism of KH polycarboxylic acid type water reducing agent has been studied. The results show that: KH polycarboxylic acid type water reducing agent can control the chemical shrinkage, resulting in the reducing by 20% of the chemical shrinkage of 1 d, and over 30% of the chemical shrinkage of 28 d; it also has strongly retarding ability, controlling the heat of hydration and deferring the structure to establish; the groups of -OH, -COO-,-SO3-,-OCH2CH2-, have adsorbing, complexing, electrostatic repulsion and steric hindrance abilities to control the hydration of the C3A and C3S, but doesnt effect the development of the structure.