硅灰是超高强混凝土(UHSC)中最难被分散的组分，超高强混凝土性能提升需要硅灰的有效分散.通过自由基反应，将乙烯基三乙氧基硅烷接枝引入了主链结构中，合成了一种含有硅烷基团的聚羧酸减水剂(PCES).采用微坍落度法研究了 PCES 对水泥-硅灰浆体流动性的影响规律.用有机碳分析仪研究了PCES在水泥净浆和硅灰表面的吸附性能.研究结果表明，聚羧酸减水剂分子结构中引入硅烷基团后，分散水泥-硅灰浆体的能力明显提高，在水泥颗粒表面吸附量增加幅度不大，而在硅灰表面的吸附量有较大幅度增加.PCES能够在含有羟基的硅灰表面同时发生物理吸附和化学吸附，硅灰表面吸附更多的减水剂分子后，其空间排斥能增加，这可能是PCES分散能力提升一个机理.相较普通聚羧酸减水剂，硅烷改性的聚羧酸减水剂更适宜配制超高强混凝土.
Silica fume is the hardest dispersing component in ultra high strength concrete (UHSC),and im-provement of UHSC performance need effective dispersion of silica fume.In this study,silanized polycarboxy-late superplastizer (PCES)was synthesized through radical copolymerization,which Vinyltriethoxysilane was in-troduced to backbone structure of polymer.The influence of PCES on fluidity of cement-silica fume pastes was analysed by mini-slumps method.Adsorption properties of PCES on surface of cement and silica fume were in-vestigated by TOC.Results shows:compared with traditional polycarboxlate,PCES showed a higher dispersing capability in cement-silica fume pastes,Adsorption amount increased marginally in cement,while sharply in sil-ica fume.The surface of silica fume existed hydroxyl,chemical adsorption and electrostatic adsorption of PCES happened simultaneously.Owing to additional chemical adsorption,more molecules existed in surface of parti-cles,they can offer stronger steric hindrance repulsive force,this may be a mechanism that PCES possessed high dispersion effectiveness in cement-silica fume pastes.Compared to traditional polycarboxlate,PCES was more suitable for ultra high strength concrete.
参考文献
| [1] | Tina Oertel;Uta Helbig;Frank Hutter.Influence of amorphous silica on the hydration in ultra-high performance concrete[J].Cement and Concrete Research,2014:121-130. |
| [2] | A. Bagheri;T. Parhizkar;H. Madani;A. M. Raisghasemi .The influence of different preparation methods on the aggregation status of pyrogenic nanosilicas used in concrete[J].Materials and structures,2013(1/2):135-143. |
| [3] | Deyu Kong;Xiangfei Du;Su Wei;Hua Zhang;Yang Yang;Surendra P. Shah.Influence of nano-silica agglomeration on microstructure and properties of the hardened cement-based materials[J].Construction and Building Materials,2012:707-715. |
| [4] | 高南箫,刘加平,冉千平,田倩,张建纲.两亲性低分子聚醚减缩剂减缩机理探索[J].功能材料,2012(14):1931-1935. |
| [5] | 刘金芝,周栋梁,江姜,冉千平,刘加平.具有缓释作用的聚羧酸分散剂的制备及机理研究[J].功能材料,2013(z2):277-279. |
| [6] | 张正国,高保娇,雷青娟,陈志萍.在交联聚乙烯醇微球表面接枝聚合甲基丙烯酸及接枝微球对含氮代谢及药物分子吸附特性的初探[J].功能材料,2012(12):1564-1568. |
| [7] | Ran Qianping;Wu Shishan;Zhang Yuncan.Research progress of comb-like coploymer dispersant for cememnt[J].Polymer Bulletin,2014(02):68-77. |
| [8] | A. Lange;T. Hirata;J. Plank.Influence of the HLB value of polycarboxylate superplasticizers on the flow behavior of mortar and concrete[J].Cement and Concrete Research,2014:45-50. |
| [9] | Qianping Ran;Changwen Miao;Jiaping Liu .Performance and Mechanism of a Multi-Functional Superplasticizer for Concrete[J].Materials transactions,2006(6):1599-1604. |
| [10] | Lei Lei;Johann Plank .Synthesis and Properties of a Vinyl Ether-Based Polycarboxylate Superplasticizer for Concrete Possessing Clay Tolerance[J].Industrial & Engineering Chemistry Research,2014(3):1048-1055. |
| [11] | Johann Plank;Christof Schroefl;Mirko Gruber;Matthias Lesti;Roland Sieber .Effectiveness Of Polycarboxylate Superplasticizers In Ultra-high Strength Concrete: The Importance Of Pce Compatibility With Silica Fume[J].Journal of advanced concrete technology,2009(1):5-12. |
| [12] | Li Y;Yang C;Zhang Y et al.Study on dispersion,ad-sorption and flow retaining behaviors of cement mortars with TPEG-type polyether kind polycarboxylate super-plasticizers[J].Construction and Building Materials,2014,64:324-332. |
| [13] | Jiaping Liu;Qianping Ran;Changwen Miao .Effects of Grafting Densities of Comb-Like Copolymer on the Dispersion Properties of Concentrated Cement Suspensions[J].Materials transactions,2012(3):553-558. |
| [14] | Flatt RJ;Schober I;Raphael E;Plassard C;Lesniewska E .Conformation of Adsorbed Comb Copolymer Dispersants[J].Langmuir: The ACS Journal of Surfaces and Colloids,2009(2):845-855. |
| [15] | Ran Qianping .Research on structure,adsorption,disper-sion of comb copolymer and its work mechanism[D].Nanjing:Nanjing University,2007. |
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