酰胺基团对聚羧酸减水剂早强性能的影响研究

Effect of different amide groups on the early-strength properties of polycarboxylic superplaticizers

以丙烯酰胺(AM)和N-羟甲基丙烯酰胺(HAM)分别替代部分丙烯酸(AA),合成早强型聚羧酸减水剂,并对减水剂的分散性、早强性及其机理进行了分析。结果表明,在分散性能变化较小的情况下,AM或HAM均在替代10%物质的量的AA时,所合成的早强型聚羧酸减水剂胶砂抗压强度最高。水泥水化热分析表明,AM有助于水泥水化放热峰提前,而HAM则显著增大早期水泥水化放热量。扫描电镜分析同样表明,AM有助于1 d水化产物C-S-H凝胶的形成,而HAM在3 d时诱导形成较多的水化产物。

Acrylamide(AM)and N-methylol acrylamide(HAM)were applied to substitute the acrylic acid(AA)in synthesizing the early-strength polycarboxylic superplasticizer,and the dispersibility,early strength and mechanism of the superplasticizer were analyzed.It is illustrated that as 10%molar mass of AA was substituted by AM or HAM,the compressive strength of mortar mixed with superplasticizers gave the highest value with barely affecting the dispersion ability.As revealed by the isothermal calorimetry measurements and SEM,addition of AM leads to an advance of hydration peak and much more C-S-H gel at the age of 1 d while the HAM contributes to higher hydration heat and more hydration products at the age of 3 d.