聚羧酸减水剂缓凝机理的研究

Retarding Mechanism of Polycarboxylic Acid Type Water-reducing Agent

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 polycarboxylie 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 doesn＇t effect the development of the structure.