首页期刊信息编委及顾问期刊发行联系方式使用帮助常见问题ENGLISH
位置:首页 >> 正文
超高强混凝土中各组分与聚羧酸系超塑化剂之间的相互作用(英文)
作者:SCHRFLC GRUBERM PLANKJ  
单位:Technische Universitt München Chair for Construction Chemicals Garching  
关键词:超高强混凝土  硅灰  聚羧酸系超塑化剂  助剂  分散机理 
分类号:TU528.042.8
出版年,卷(期):页码:2010,38(9):1605-1612
DOI:
摘要:

超高强混凝土(ultra-high strength concrete,UHSC)的水灰比小于0.25,含有大量的硅灰等微细组分,这有利于颗粒的最优紧密堆积。硅灰的表面化学效应以及较大的表面积使其成为UHSC中最难被分散的组分。由甲基丙烯酸、甲基丙烯酸酯及甲代烯丙基磺酸合成的聚羧酸系超塑化剂能使水泥颗粒被有效润湿,然而烯丙醚-马来酸酐合成的聚羧酸系超塑化剂可以很好地分散硅灰。这2种不同的聚羧酸系超塑化剂的复合可以使其拥有不同的分子结构,从而赋予超高强混凝土很好的流动性。当只加入1种聚羧酸系超塑化剂时其掺量为1%(质量分数,下同),而当加入这种复合聚羧酸系超塑化剂时掺量为0.5%就足够了。这2种类型的聚羧酸系超塑化剂的协同效应是由于它们的选择性吸附:甲基丙烯酸盐基的聚羧酸系超塑化剂主要吸附在水泥颗粒表面,而烯丙醚基聚羧酸系超塑化剂主要吸附在硅灰颗粒表面。实验表明:小分子量的有机酸阴离子(如:柠檬酸盐、葡萄糖酸盐及酒石酸盐中的阴离子)与聚羧酸系超塑化剂之间具有潜在的协同作用。只需加入0.1%的这些阴离子即可显著提高烯丙醚基聚羧酸系超塑化剂的作用效果。这些阴离子可以起到一种辅助作用,它们同时吸附在水泥颗粒表面以及硅灰颗粒表面。水泥颗粒的表面首先由这些阴离子所占据,而硅灰颗粒表面吸附了烯丙醚基聚羧酸系超塑化剂和这些阴离子。这些阴离子起到了一种很强的静电分散效应,使烯丙醚基聚羧酸系超塑化剂的空间位阻效应得到加强。虽然聚羧酸系超塑化剂阴离子具有缓凝作用,但是使用这种复合聚羧酸系仍能制备出高早强混凝土。

online women that cheat with married men married woman looking to cheat
read wifes cheat reasons wives cheat on their husbands
how to catch a cheater redirect go
read percentage of women who cheat signs of infidelity
why do wife cheat on husband why men cheat how to cheat wife
abortion las vegas abortion clinics in the bronx abortion pictures

The ultra-high strength concrete(UHSC) is characterized by a water cement ratio of below 0.25 and a high content of fines such as silica fume for optimized packing density.In the UHSC,due to its surface chemistry and large surface area,silica fume is the most difficult component to be dispersed.Polycarboxylates(PCEs) made of methacrylic acid,MPEG methacrylate ester and methallylsulfonic acid effectively liquefies cement,whereas allyl ether-maleic anhydride based PCEs disperse silica fume well.Thus,a combination of these PCE types which possess different molecular architectures provides superior flowability to UHSC.A low dosage of 0.5% by mass of cement of this combination is sufficient,whereas about 1%(by mass of cement) is required when the individual PCEs are utilised.The reason for this synergistic effect of these of PCEs is their selective adsorption:the methacrylate-based PCE preferentially adsorbs on cement while the allyl ether-type PCE is strongly attracted by the silica surface.Additional experiments were conducted to probe a potential synergism between organic anions(citrate,gluconate,tartrate,with small molecular mass) and PCE.It was found that addition of only 0.1% by mass of cement of these anions further enhances the effectiveness of the allyl ether-based PCE,resulting in an even lower PCE dosage.It was mechanistically identified that these anions act as supplemental effect which adsorb simultaneously on both cement and silica fume.This way,the surface of cement is primarily occupied by the anion,whereas on the surface of silica,concomitant adsorption of the allyl ether-based PCE,and the anion occurs.The anion exercises a strong electrostatic dispersion effect which compliments the steric effect of the allyl ether-based PCE.This admixture combination was found to provide a high early strength,in spite of the known retarding effect of the carboxylate anions.

how to cheat women who want to cheat wife cheat story
abortion las vegas period after abortion abortion pictures
amoxicillin amoxicillin amoxicillin
abortion pill abortion pill abortion pill
基金项目:
German Research Foundation
作者简介:
redirect why do women cheat on their husbands unfaithful husband
redirect go why women cheat on men they love
read click link
doxycycline doxycycline doxycycline
参考文献:

[1] WALRAVEN J. High performance concrete: A material with a large potential [C]// 8th International Symposium on Utilization of High-Strength and High-Performance Concrete, Tokyo, Japan, October 27-29, 2008: 1-12. [2] UCHIDA Y, FISCHER G, HISHIKI Y, et al. Review of Japanese recommendations on design and construction of different classes of fiber reinforced concrete and application examples [C]// 8th Interna- tional Symposium on Utilization of High-Strength and High-Perfor- mance concrete, Tokyo, Japan, October 27-29, 2008: 92-110. [3] COPPOLA L, TROLI R, CERULLI T, et al. The influence of materials on the performance of reactive powder concrete [C]// International Conference on High-Performance Concrete and Performance and Quality of Concrete Structures, Florianopolis, Brasil, June 5-7, 1996: 502-513. [4] SAKAI E, KAKINUMA Y, YAMAMOTO K, et al. Relation between the shape of silica fume and the fluidity of cement paste at low water to powder ratio [J]. J Adv Concr Technol 2009, 7(1): 13-20. [5] SCHRFL C, GRUBER M, PLANK J. Structure performance relationship of polycarboxylate superplasticizers based on methacrylic acid esters in ultra high performance concrete [C]// FEHLING E, SCHMIDT M, STüRWALD E, eds. Ultra High Performance Concrete (UHPC)-Pro- ceedings of the 2nd International Symposium on Ultra High Perform- ance Concrete, Kassel, Germany: Kassel University, 2008: 383-390. [6] YOSHIOKA K, SAKAI E, DAIMON M, et al. Role of steric hindrance in the performance of superplasticizers for concrete [J]. J Am Ceram Soc, 1997, 80(10): 2667-2671. [7] PLANK J, DUGONJIC-BILIC F, RECALDE LUMMER N. Modi- fication of the molar anionic charge density of acetone-formaldehyde- sulfite dispersant to improve adsorption behavior and effectiveness in presence of CaAMPS-co-NNDMA cement fluid loss polymer [J]. J Appl Poly Sci, 2009, 111(4): 2018-2024. [8] PLANK J, SACHSENHAUSER B. Impact of molecular structure on zeta potential and adsorbed conformation of α-allyl-ω-methoxypol- yethylene glycol-maleic anhydride superplasticizers [J]. J Adv Concr Technol, 2006, 4(2): 233-239. [9] PLANK J, PLLMANN K, ZOUAOUI N, et al. Synthesis and per- formance of methacrylic ester based polycarboxylate superplasticizers possessing hydroxy terminated poly (ethylene glycol) side chains [J]. Cem Concr Res, 2008, 38(10): 1210-1216. [10] OHTA A, SUGIYAMA T, UOMOTO T. Study of dispersing effects of polycarboxylate-based dispersant on fine particles (SP-195-14) [C]// Malhotra V M ed. Proceedings of the 6th CANMET/ACI International Conference on Superplasticizers and Other Chemical Admixtures in Concrete. Farmington Hills, MI/USA: American Concrete Institute, 2000: 211-227. [11] API Recommended Practice 10B: Recommended Practice for Testing Well Cements [S]. American Petroleum Institute: Washington D C, USA, 1997. [12] MAZANEC O, SCHIESSL P. Improvement of UHPC properties through an optimized mixing procedure [C]// 8th International Symposium on Utili- zation of High-Strength and High-Performance Concrete, Tokyo, Japan, October 27-29, 2008: 307-313. [13] PLANK J, SCHRFL C, GRUBER M, et al. Effectiveness of polycar- boxylate superplasticizers in ultra-high strength concrete: the importance of PCE compatibility with silica fume [J]. J Adv Concr Technol, 2009, 7(1): 5-12.

redirect husband cheated unfaithful husband
read cheat on husband signs of infidelity
服务与反馈:
文章下载】【加入收藏
中国硅酸盐学会《硅酸盐学报》编辑室
京ICP备10016537号-2
京公网安备 11010802024188号
地址:北京市海淀区三里河路11号    邮政编码:100831
电话:010-57811253  57811254    
E-mail:jccs@ceramsoc.com