硅酸盐学报

含硅烷官能团聚羧酸减水剂对水泥浆体流动性和力学性能的影响

单位：1. 土木工程安全与耐久教育部重点实验室清华大学土木工程系北京 100084 2. 东南大学先进土木工程材料协同创新中心南京 211189 3. 中国矿业大学北京化学工程系北京 100083

关键词：硅烷聚羧酸减水剂流动性吸附强度

分类号：TU528.042.2

出版年,卷(期):页码：2014,42(5):635-641

DOI：10.7521/j.issn.0454-5648.2014.05.13

摘要：

用γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH570)部分或全部取代聚羧酸减水剂合成过程中的丙烯酸(AA)单体，通过自由基聚合合成了一系列不同组成的硅烷改性聚羧酸减水剂(SPC)。研究了引入硅烷官能团后，减水剂对水泥净浆流动度的影响规律。采用总有机碳分析法(TOC)研究了硅烷改性聚羧酸减水剂的吸附行为。最后评价了其对水泥砂浆强度发展的影响。结果表明：聚羧酸减水剂(PC)分子中羧基含量越高，其在水泥颗粒表面的吸附量越大，对水泥浆体的分散性越好；在减水剂分子结构中引入硅氧烷官能团，水解生成的硅羟基可以作为吸附基团，提高减水剂分子在水泥颗粒表面的吸附能力，从而提高减水剂对水泥的分散能力；且硅羟基在水泥表面的吸附为化学吸附，因此其吸附能力大于羧基官能团(-COOH)；HPEG和KH570的摩尔比为1:1或1:2的共聚物有利于砂浆7、28 d抗压强度的发展。

A series of γ-methacryloxypropyltrimethoxysilane (KH570) modified superplasticizers (SPC) were synthesized through radical copolymerizationin aqueous phase, in which acrylic acid (AA) was completely or partially replaced by the KH570. The dispersive property and adsorption ofthe SPC were analyzed via flow table test and total organic carbon (TOC) measurement. In addition, the influence of the SPC on the strength development of cement mortars was also investigated. The results show that there are more carboxyl groups in polycarboxylate(PC) molecules, leading to a greater adsorption amount on cement surface and a higher dispersing capability in cement pastes. The incorporation of silanolgroups in polycarboxylate chains that is produced by the hydrolysis of siloxane group promotes the adsorption of superplasticizer molecules on cement surface. The adsorption of silanol groups on cement surface is chemical adsorption via the condensation to form Si-O-Si covalent with cement surface, which is stronger than the physical adsorption of the carboxyl groups (-COO^-). The copolymerization of silane monomers in polycarboxylate molecules increases the adsorption amount of the polymers,hence enhancing the dispersive performance. The positive strength development of mortars after 7-d and 28-d curing can be obtained when the mole ratios of monomers (methallypolyoxethylene ether to KH570) are 1:1 and 1:2, respectively.

基金项目：

自然科学基金资助项目(51173094， U1262107)

作者简介：

第一作者：孔祥明(1974—)，男，博士，副研究员E-mail:kxm@tsinghua.edu.cn

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