沸石减水保塑剂的特性与工程应用

Characteristics and Engineering Application of Zeolite Plastic-keeping Water Reducer

浏览量:

关键词:

天然沸石;高效减水剂;工作度;扩展度;可泵性

Key words:

Natural zeolite powder; Superplasticizer; Workability; Fluidity; Pumpability

刊期:

2009年第2期

DOI:

文章编号:

1000-4637(2009)02-01-04

基金项目:

作者:

冯乃谦1,石云兴2,牛全林3

单位:

1.清华大学,北京100084;2.中建材料工程研究中心,北京102600;3.山东理工大学,淄博255049

摘要

摘   要:以天然沸石超细粉吸附高效减水剂,制得沸石减水保塑剂。沸石减水保塑剂可用于普通混凝土、高性能混凝土及超高性能混凝土,使混凝土流动性增大,并能控制流动性的经时变化;这主要是由于在混凝土中它能缓慢被释出,从而维持水泥粒子对减水剂的吸附量,使水泥粒子表面具有较稳值的Zeta电位,使水泥浆常处于分散状态。在超高性能混凝土中,它还能降低新拌混凝土的粘度,便于泵送施工。沸石减水保塑剂掺入混凝土中还能改善硬化混凝土的结构,提高混凝土的强度。

Abstract: Absorption and desorption of superplasticizer by natural zeolite powder were investigated,and a zeolite plastic-keeping  water reducer with natural zeolite powder as a carrier was produced. The addition of zeolite superplasticizer in concrete, the HPC and UHPC can increase their fluidity and  slump, while the loss of fluidity and slump are effectively controlled. The causes are mainly that, the superplasticizer can be released gradually in the concrete from absorpted surface of zeolite,  that will maintain the concentration of superplaticizer at the surface of cement particles, so that can maintain the surface zeta potential of cement particles and can keep the dispersing state of cement paste. It can also decrease the viscosity of fresh concrete for easy concreting of UHPC by pumping.The zeolite plasticizer can also improve the structure and increase the strength of  concrete.

结论

(1)天然沸石超细粉通过吸附与解吸,能够作为减水剂的载体,配制出沸石减水保塑剂。
(2)沸石减水保塑剂的特点是在水泥浆中或混凝土中,缓慢释放高效减水剂,使坍落度增大,流动度提高;同时还能维持坍落度和流动值在某一时间内基本不变,保证施工要求。
(3)水泥浆体或混凝土的流动性及经时变化,主要受水泥颗粒表面吸附减水剂量的影响。当水泥颗粒表面对减水剂吸附量维持在某一水平时,就能维持水泥颗粒表面的Zeta电位不变,使水泥浆处于分散状态,从而控制浆体流动性或混凝土坍落度的经时损失。沸石减水保塑剂通过解吸过程,缓慢释放高效减水剂到水泥浆或混凝土中,能使Zeta电位基本不变,从而保持良好的流动性。
(4)混凝土在倒坍落度筒中流出时间短且经时变化小,有利于泵送施工。沸石减水保塑剂有利于混凝土的保塑、降粘、使流动加快。即有利于泵送施工。

参考文献

[1] 古阶祥.沸石.北京:中国建筑工业出版社,1980.
[2] 冯乃谦,李桂芝.控制混凝土坍落度损失的载体流化剂.硅酸盐学报,Vol.18,No.4,1980(8).
[3] Feng Naiqian, Zhuang Qingfeng.Two-hour zero slump loss, high strength pumpable concrete-an application Case in dam structure. ASTM. C.A, Vol.20, No.2, 1998.
[4] 冯乃谦.流态混凝土.北京:中国铁道出版社,1988.
[5] Feng, N-Q, Li. G-Z and Zang, X-W. High-strength and flowing concrete with a zeolite mineral admixture, Cem. Conc. and Aggr. 12,2.p.61,1990.
[6] 冯乃谦,石云兴.一种控制混凝土坍落度损失的外加剂的制备方法.ZL200610000802.8.中国.
[7] Hattori. K. etal. Slump retention by pebble-like Surperplasticizer, Cement Concrete, No.443 (in Japanese).
[8] 冯乃谦.天然沸石混凝土应用技术.北京:中国铁道出版社,1996.

引用本文


上一个: 对混凝土养护方法的思考与建议

下一个: 无

相关文件