黏土对聚羧酸减水剂应用性能的抑制机理  

Inhibition Mechanism of Clays on Applying Performances of Polycarboxylate Superplasticizer

作　　者：王子明[1] 吴昊[2] 徐莹[3] 刘晓[1] 

机构地区：[1]北京工业大学材料科学与工程学院,北京100124 [2]北京东方雨虹防水技术股份有限公司,北京100025 [3]中国建筑科学研究院建筑材料研究所,北京100013

出　　处：《建筑材料学报》2014年第2期234-238,279,共6页Journal of Building Materials

基　　金：国家自然科学基金资助项目(51208012)

摘　　要：测试了4种黏土的吸附率、吸水率和膨胀容,测定了蒙脱石的层间距,研究了不同黏土对聚羧酸减水剂(PCE)的吸附作用和吸附方式,分析了黏土吸附PCE后混凝土拌和物固液相体积的变化,探索了黏土对PCE应用性能的抑制机理.结果表明:黏土对PCE的吸附率远大于水泥,其中蒙脱石的吸附作用最强.PCE分子侧链嵌入蒙脱石的层间,使得蒙脱石层间距d(001)由1.443nm增加到1.863nm.黏土吸附PCE分子,使得产生分散作用的有效PCE含量降低;黏土吸附水后体积膨胀,导致混凝土拌和物中固相体积增大、液相体积减小,最终引起混凝土拌和物工作性能劣化.The adsorption rate, water absorption, volume swelling capacity of 4 kinds of clay, and the in- terlayer spacing of montmorillonite were tested. The adsorption capacity and mode of polycarboxylate su- perplasticizer（PCE） on different clays were studied. The volume change of solid and liquid phase in fresh concrete before and after adsorbing PCE by clay was calculated. The inhibition mechanism of clay on ap plying performance of PCE was explored. The results show that the adsorption of PCE on clay is higher than that on cement, and adsorption capacity of montmorillonite is the strongest of all. The side chain of PCE molecular is adsorbed into interlayers of montmorillonite, which increases the interlayer spacing （d^001~） of montmorillonite from 1. 443 nm to 1. 863 nm. Clay adsorbs more PCE and thus reduces the ef fective content for dispersing action. The volume of clay expands after absorbing water, increasing the sol id phase volume and decreasing the liquid phase volume, and finally worsening the workability of fresh concrete.

关 键 词：聚羧酸减水剂 黏土 机理 吸附 

分 类 号：TU528.042.2[建筑科学—建筑技术科学]