摘要
通过对减水剂作用下水泥浆体的流动性、凝结时间、Ca2+浓度、化学收缩、XRD的研究分析,讨论了减水剂侧链上羧基(—COOR)和聚氧乙烯基(—OC2H4—)的相对密度对水泥早龄期水化特性的影响。结果表明,随着侧链上聚氧乙烯基密度的增大,凝结时间延长,水泥浆体的流动性增大,分散效果增强,而分散保持性逐渐减小;当n(—COOR)∶n(—OC2H4—)=1∶3时,水化1min和1h的水泥塑性浆体溶液中的Ca2+浓度呈现较高值,水泥净浆早期化学收缩相对最大;1d及28d的硬化浆体的XRD分析结果也显示,当n(—COOR)∶n(—OC2H4—)=1∶3时,Ca(OH)2衍射峰最明显,水泥颗粒水化充分。因此,合理地控制—COOR与—OC2H4—的摩尔比,可以提高聚羧酸减水剂的分散性及分散保持性,调整水泥的凝结时间及早期的化学收缩特性。
Polycarboxylate type superplasticizers with different side chain structures are studied by analyzing fluidity,setting time,concentration of Ca^2＋,chemical shrinkage of cement paste and XRD of hydrated cement blended with water reducer. The result shows that the density of carboxyl （-COOR） and polyethylene glycol （-OC2H4-） of polycarboxylate type superplasticizer produces an effect on cement early hydration process. As the density of -OC2H4- increases, the setting time of cement paste is elongated,its fluidity is inereased,dispersivity is enhanced while the retentivity is gradually decreased. The concentration of Ca^2＋ in cement paste hydrated for lmin and lh is the highest when the mol ratio of（-COOR）：（-OC2H4-）= 1：3,and the chemical shrinkage of the paste is relatively the largest. At the same time,the XRD analysis of setting paste at ld and 28d also shows that when the mol ratio of （-COOR）：（-OC2H4-）=1：3,the diffraction peak of Ca （OH）2 is the sharpest. That is to say the hydration process of the cement is sufficient. Therefore, if the mol ratio of （-COOR） ：（-C2H4-） is controlled reasonably,the dispersivity and retentivity of polycarboxylate type superplasticizer can be improved,the setting time and early chemical shrinkage of cement can be adjusted.
出处
《新型建筑材料》
北大核心
2008年第6期41-44,共4页
New Building Materials
基金
国家"973"项目资助(2001CB610704-3)
关键词
聚羧酸减水剂
侧链密度
羧基
聚氧乙烯基
水泥早期水化
polycarboxylate type superplasticizer
side chain density
carboxyl
polyethylene glycol
cement early hydration
作者简介
马保国，男，1957年生，博导，教授。地址：武汉市洪山区珞狮路122号，电话：027—87160951，E-mail：mbgjob@163．com。
