抑制粘土对聚羧酸减水剂负效应的添加剂及其作用机理

发布时间：2018-09-19 14:59

【摘要】：集料附含泥会降低聚羧酸减水剂的减水分散性能,其中集料附含粘土是泥中对聚羧酸减水剂负效应最显著的组分。粘土吸附聚羧酸减水剂使得对水泥起分散作用的有效聚羧酸减水剂减少和粘土吸附拌合水使得提供浆体流动的自由水减少是粘土影响掺聚羧酸减水剂水泥净浆、砂浆和混凝土工作性能的主要原因。不同种类的粘土对聚羧酸减水剂的影响程度不同,吸附能力和膨胀能力强的蒙脱土较伊利土和高岭土对聚羧酸减水剂的负效应更大。目前针对粘土对聚羧酸减水剂负效应抑制措施的研究还处于起步阶段,还没有一种普遍适用的解决办法。本文从“释放粘土吸附的拌合水”、“选取吸附能力强的添加剂优先被粘土吸附从而减少粘土对聚羧酸减水剂的吸附”和“防止粘土膨胀以减少对拌合水和聚羧酸减水剂的吸附”三个方面考虑,选取了几种陶瓷减水剂、粘土吸附剂和粘土防膨剂作为添加剂与聚羧酸减水剂复配使用,通过宏观试验研究了添加剂的抑制效果和微观试验探讨了添加剂的抑制机理,以期为解决粘土对聚羧酸减水剂的负效应提供一些思路。研究了三聚磷酸钠、聚乙二醇-4000、亚甲基蓝、三甲基十六烷基溴化铵和KCl五种添加剂掺量对掺聚羧酸减水剂含粘土(钠基蒙脱土、钙基蒙脱土、伊利土和高岭土)水泥净浆流动度的影响,结果表明,三聚磷酸钠和亚甲基蓝抑制粘土对掺聚羧酸减水剂水泥净浆流动度负效应的效果不明显,聚乙二醇-4000、三甲基十六烷基溴化铵和KCl在合适掺量范围内能够一定程度上提高掺聚羧酸减水剂含粘土水泥净浆的流动度,并且三种添加剂对钠基蒙脱土和钙基蒙脱土的抑制效果较对伊利土和高岭土好。根据水泥净浆试验结果,选取了对蒙脱土抑制效果较好的聚乙二醇-4000、三甲基十六烷基溴化铵和KCl三种添加剂,研究了其掺量对掺聚羧酸减水剂含蒙脱土砂浆扩展度和强度的影响,结果表明,聚乙二醇-4000和三甲基十六烷基溴化铵单掺时对掺聚羧酸减水剂含蒙脱土砂浆扩展度提高幅度较KCl单掺时大,聚乙二醇-4000和KCl对砂浆强度几乎无影响,而三甲基十六烷基溴化铵会严重降低砂浆强度。三种添加剂复配对砂浆扩展度的改善效果好于单掺,但有三甲基十六烷基溴化铵存在时仍会大幅度降低砂浆强度。聚乙二醇-4000掺量为0.3%和KCl掺量为1.5%复配在不降低强度的前提下同样能大幅度提高掺聚羧酸减水剂含粘土混凝土的工作性能。通过总有机碳试验、ζ电位试验和粘土膨胀容试验,探讨了聚乙二醇-4000、三甲基十六烷基溴化铵和KCl三种添加剂抑制粘土对聚羧酸减水剂负效应的机理,结果表明,聚乙二醇-4000、三甲基十六烷基溴化铵和KCl能够减少粘土对聚羧酸减水剂的吸附量,能够提高含粘土水泥浆体体系ζ电位和抑制钠基蒙脱土和钙基蒙脱土膨胀从而减少对聚羧酸减水剂和拌合水的吸附是三种添加剂能够抑制粘土对掺聚羧酸减水剂水泥净浆、砂浆和混凝土工作性能负效应的主要原因。
[Abstract]:Adsorbed polycarboxylic superplasticizer reduces the dispersibility of polycarboxylic acid superplasticizer, and clay is the most significant component of the sludge which has the most negative effect on polycarboxylic acid superplasticizer. The decrease of clay is the main reason for the influence of clay on the performance of cement paste, mortar and concrete mixed with polycarboxylic superplasticizer. The research on the negative effect inhibition measures of acid water reducers is still in its infancy, and there is no universal solution. This paper discusses the problems of "releasing the mixing water adsorbed by clay", "selecting the additives with strong adsorptive capacity to be adsorbed by clay in preference so as to reduce the adsorption of clay to polycarboxylic acid water reducer" and "preventing clay expansion to reduce the adsorption of polycarboxylic acid water reducer". Considering the adsorption of mixing water and polycarboxylic acid superplasticizer, several ceramic superplasticizers, clay adsorbent and clay anti-swelling agent were selected as additives and polycarboxylic acid superplasticizer were used in combination. The inhibition effect of additives and the inhibition mechanism of additives were studied by macro-test and micro-test in order to solve the problem of clay on superplasticizer. The influence of the contents of sodium tripolyphosphate, polyethylene glycol-4000, methylene blue, trimethylhexadecyl ammonium bromide and KCl on the fluidity of clay (sodium montmorillonite, calcium montmorillonite, illite and kaolin) cement paste containing polycarboxylic acid superplasticizer was studied. Sodium polyphosphate and methylene blue have no obvious effect on inhibiting the negative effect of clay on the fluidity of cement paste with polycarboxylic superplasticizer. Polyethylene glycol-4000, trimethylhexadecyl ammonium bromide and KCl can improve the fluidity of clay-containing cement paste with polycarboxylic superplasticizer to a certain extent within the appropriate dosage range, and three additives have effect on sodium. Based on the test results of cement paste, three additives, polyethylene glycol-4000, trimethylhexadecyl ammonium bromide and KCl, which had better inhibition effect on montmorillonite, were selected to study the expansion and strength of montmorillonite-containing mortar mixed with polycarboxylic acid water reducer. The results show that the expansion of montmorillonite mortar with polyethylene glycol-4000 and trimethylhexadecyl ammonium bromide is larger than that with KCl. The strength of the mortar is almost unaffected by polyethylene glycol-4000 and KCl, while the strength of the mortar is severely reduced by trimethylhexadecyl ammonium bromide. The strength of mortar can be greatly reduced in the presence of trimethylhexadecyl ammonium bromide. The performance of clay concrete with polycarboxylic superplasticizer can also be greatly improved by mixing 0.3% polyethylene glycol-4000 and 1.5% KCl without reducing the strength. The mechanism of polyethylene glycol-4000, trimethylhexadecyl ammonium bromide and KCl as additives to inhibit the negative effect of clay on polycarboxylic superplasticizer was studied by total organic carbon test, zeta potential test and clay swelling capacity test. The results showed that polyethylene glycol-4000, trimethylhexadecyl ammonium bromide and KCl could reduce the negative effect of clay on polycarboxylic superplasticizer. Adsorption capacity can increase_potential of clay-containing cement paste system and inhibit expansion of Na-montmorillonite and Ca-montmorillonite so as to reduce adsorption of polycarboxylic superplasticizer and mixing water.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528.042.2

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