聚羧酸减水剂与增强组分的复合效应及原理

The Composition Effect and Mechanism of Polycarboxylate Superplasticizers and Early Strength Agent

关于聚羧酸减水剂与增强组分进行复配的机理尤其是水化进程的研究较少。本工作通过聚羧酸减水剂复配有机类和无机类早强剂,测试净浆流动度和流变参数、砂浆强度、水泥水化热、水泥水化产物的XRD谱和TG-DTA曲线,以分析研究水泥基材料的流动及强度的发展规律。研究表明,无机类早强剂硫代硫酸钠(Na2(S2O3))与氯化钙(CaCl2)的加入会显著降低聚羧酸减水剂的减水率,破坏聚羧酸减水剂的空间位阻效应;甲酸钙(Ca(HCOO)2)、硫氰酸钠(NaSCN)及三乙醇胺(TEA)的加入对聚羧酸减水剂的减水率无显著影响。通过检测24h水泥水化热可知,随着早强剂的加入,水泥浆体在水化加速期的水化程度相应提高。通过XRD、TG-DTA分析看出,早强剂的加入可显著提高3d水泥水化进程中C-S-H凝胶、氢氧化钙(Ca(OH)2)以及钙矾石(AFt)的生成速率,但对水泥浆体28d水化进程无显著影响。

The composition mechanism of polycarboxylate superplasticizers and early strength agent is not well studied,especially the hydration process.In this study,the organic and inorganic early strength agents were compounded,followed by the measurement of the cement paste fluidity,cement mortar strength and viscosity.The test of cement hydration heat,XRD,TG-DTA were used to demonstrate the hydration process.According to the research,the introduce of inorganic early strength agent such as sodium thiosulfate and calcium chloride could destroy the steric hindrance effect,leading to the significant decrease of the water-reducing rate of polycarboxylate superplasticizers.However,calcium formate,sodium thiocyanate and triethanolamine showed almost no effect on water-reducing rate.According to the test result of hydration heat of cement during 24 h,the hydration degree of cement paste can be improved during the hydration acceleration by adding early strength agent.As shown in the XRD and TG-DTA analysis,early strength agent could increase the formation of AFt,calcium hydroxide and C-S-H gel in 3 d hydration,but showed little effect on the 28 d hydration.