混凝土坍落度损失机理及保坍类材料研究

发布时间：2018-05-15 07:37

本文选题：水泥 + 蒙脱石　；参考：《武汉理工大学》2015年硕士论文

【摘要】：本文依托于国家自然科学基金(51408448)“聚羧酸减水剂与羟基羧酸盐缓凝剂的分子结构耦合机理”和国家自然科学基金项目(51178363)“混凝土Thaumasite侵蚀机理及防护措施的研究”,针对混凝土坍落度经时损失引起的施工问题,通过制备聚羧酸类缓释型保坍剂,并复配高性能减水剂和缓凝剂,经过试验找出性能优良的混凝土保坍材料。同时,通过探讨蒙脱石与保坍材料的相互作用机理,找出有效的抗蒙脱石保坍材料,解决混凝土含泥量高引起的坍落度损失大的问题。最后,在夏天高温环境和混凝土原材料含泥量较高的条件下,将后掺抗泥型保坍材料应用于混凝土拌合中,为解决混凝土坍落度损失问题提供一定的方法。具体内容如下:1制备聚羧酸类减水剂和缓释型保坍剂,并研究保坍剂的作用机理,为制备保坍材料体系提供理论基础,具体内容如下:(1)通过气象色谱测定马来酸酐单甲酯的转化率,发现最佳合成条件为:反应时间105min,顺丁烯二酸酐/甲醇的摩尔比为1.1:1,催化剂选用浓硫酸,转化率达到84.69%。(2)检测保坍剂的稳定性,丙烯酸羟乙酯型保坍剂静置3个月后保坍性能优良,马来酸酐单甲酯型保坍剂在静置过程中,结构中的酯基发生水解反应,变成性能优良的高效减水剂。(3)通过核磁能谱的测定,发现保坍剂的作用机理是分子结构中酯基的在水化过程中水解从而“缓慢释放”羧基,与高性能减水剂相比,它可以长时间保持分散性能。2复配减水剂、保坍剂和缓凝剂,寻找出性能优良的保坍材料体系,具体内容如下:(1)复配保坍剂与减水剂时,两者匹配性较好,特别是掺入0.8g JS-3减水剂和0.2g BT保坍剂时效果最优,初始流动度为210mm,1h流动度为240mm。(2)缓凝剂与保坍剂或减水剂在水泥颗粒表面发生竞争吸附,可以在保证净浆初始流动度的基础上,有效抑制1h的净浆流动度损失,其中影响力大小为STTPSGFS。(3)JS-3-BT-缓凝剂的三元组分保坍类材料的性能优良,特别是在各组分质量为JS-3(0.8g)-BT(0.2g)-缓凝剂(0.2g)时,水泥净浆的初始流动度在220~235mm,1h流动度在240~255mm。3粘土矿物中以蒙脱石(钙基)为代表,其掺入水泥中会明显影响水泥净浆流动性能,通过研究其对聚羧酸减水剂的吸附机理,找出合适的材料体系抑制蒙脱石对减水剂的吸附,具体内容如下:(1)当水泥中掺入蒙脱石,水泥净浆的初始流动度和1h流动度大幅降低,且随着蒙脱石掺量的增加而降幅增大。(2)蒙脱石掺入不同的聚羧酸减水剂或保坍剂后,在105℃的真空干燥箱中烘干后,用XRD测定蒙脱石层间距,发现蒙脱石层间距变大,由1.51nm增加到1.63~1.70nm,同时用TOC测试蒙脱石对聚羧酸减水剂的吸附远大于水泥对聚羧酸减水剂的吸附,所以当水泥中混入蒙脱石会导致减水剂的有效利用率大大降低,是水泥净浆经时损失很大的原因。(3)当水泥-蒙脱石体系中同时掺入聚羧酸减水剂和缓凝剂时,可以保证水泥净浆的初始流动性能,抑制净浆的经时损失。这是因为缓凝剂会与蒙脱石发生离子交换,抑制了蒙脱石对聚羧酸减水剂的吸附,保证了水泥颗粒对减水剂的吸附。(4)蒙脱石吸附聚羧酸减水剂的方式是部分聚羧酸减水剂的侧链吸附到蒙脱石的层间。4当混凝土含泥量较高或高温环境下,用后掺保坍材料的方式解决混凝土坍落度经时损失过大问题,具体如下:(1)当混凝土中含泥量较高时(8%),混凝土单掺减水剂或保坍剂时,混凝土的坍落度损失较快,60min是坍落度为0mm,已经不具备施工性能。采用减水剂-保坍剂-缓凝剂的三元组分保坍材料,可以有效地抑制混凝土的坍落度损失,在夏季较高的温度下,可以保证混凝土的60min坍落度在180mm以上,保证了施工性能。(2)采用分两次掺入保坍材料的方法可以保证混凝土120min的坍落度在180mm以上,满足施工要求。保坍材料的初掺和后掺比例宜选用为70%和30%或80%和20%。
[Abstract]:This paper is based on the National Natural Science Fund (51408448) "the molecular structure coupling mechanism of Polycarboxylic Water reducing agent and hydroxy carboxylate retarder" and the National Natural Science Fund Project (51178363) "Research on the corrosion mechanism and protective measures of concrete Thaumasite", in view of the construction problems caused by the time loss of the slump of the coagulant soil, through the system, The polycarboxylic acid slump retaining agent was prepared, and the high performance water reducing agent and retarder were mixed, and the concrete slump material with good performance was found through the experiment. At the same time, the effective anti montmorillonite slump material was found out by discussing the interaction mechanism of the montmorillonite and the slump material, and the large slump loss caused by the high mud content of the coagulant soil was solved. Finally, under the condition of high temperature environment in summer and high mud content of concrete raw materials, it will be applied in concrete mixing with mud anti slump material to solve the problem of concrete slump loss. The specific contents are as follows: 1 the preparation of Polycarboxylic Water reducing agent and sustained release type slump agent, and the mechanism of the action of the slump agent are studied. In order to provide the theoretical basis for the preparation of slump protection material system, the following contents are as follows: (1) the optimum synthesis conditions are as follows: reaction time 105min, the molar ratio of maleic anhydride / methanol to 1.1:1, concentrated sulfuric acid in the catalyst, and the conversion of 84.69%. (2) to detect the stability of the slump agent. The slump retention agent of the hydroxyethyl acrylate type is excellent for 3 months. During the static process, the ester group of maleic anhydride monomethyl ester type is hydrolyzed to a high performance superplasticizer. (3) through the determination of NMR spectra, it is found that the mechanism of the slump agent is in the hydration process of the ester group in the molecular structure. The hydrolysis can "slow release" carboxyl group. Compared with the high performance water reducing agent, it can maintain the dispersible.2 water reducing agent for a long time, the slump agent and the retarder, and find out the good properties of the slump material system. The specific contents are as follows: (1) when the compound and the water reducing agent are combined, the match is better, especially the 0.8g JS-3 water reducing agent and the 0.2g. BT has the best effect, initial flow degree is 210mm, 1H flow degree is 240mm. (2), and the retarder and slump agent or water reducing agent are competitive adsorption on the surface of cement particles. On the basis of guaranteeing the initial flow degree of the pulp, the flow degree loss of 1H is effectively suppressed, and the influence size is three yuan of STTPSGFS. (3) JS-3-BT- retarder. The properties of the components are excellent, especially when the mass of each component is JS-3 (0.8g) -BT (0.2g) - retarder (0.2g), the initial flow degree of the cement paste is 220~235mm, and the 1H fluidity is represented by the montmorillonite (calcium base) in the clay minerals of 240~255mm.3, which will obviously affect the flow performance of cement paste in the mud. The adsorption mechanism of the carboxylic water reducing agent was found to find the suitable material system to inhibit the adsorption of the montmorillonite on the water reducing agent. The specific contents are as follows: (1) when the cement is added to the montmorillonite, the initial flow degree and the 1H flow degree of the cement paste are greatly reduced, and the decrease increases with the increase of the amount of montmorillonite. (2) the montmorillonite is mixed with different polycarboxylate water reducing agents or After the slump agent was dried in a vacuum drying box at 105 C, the interval between the montmorillonite layer was measured by XRD. It was found that the spacing of the montmorillonite increased from 1.51nm to 1.63~1.70nm. At the same time, the adsorption of montmorillonite to Polycarboxylic Water reducing agent was far greater than that of cement to the polycarboxylic water reducing agent. So when the cement was mixed with montmorillonite, the water reducing agent would lead to the water reducing agent. The effective utilization ratio is greatly reduced, which is the cause of great loss of cement paste. (3) when the cement montmorillonite system is mixed with Polycarboxylic Water reducing agent and retarder, the initial flow performance of cement paste can be guaranteed and the time loss of the pulp can be suppressed. This is because the retarder will exchange the montmorillonite with the montmorillonite and inhibit the montmorillonite. The adsorption of Polycarboxylic Water reducing agent ensures the adsorption of cement particles to water reducing agents. (4) the way of montmorillonite absorption of polycarboxylic acid water reducing agent is that the side chain of a partial polycarboxylic acid water reducer is adsorbed to the interlayer.4 of montmorillonite when the concrete has high mud content or high temperature environment, and the concrete slump is used to solve the time loss of the concrete slump. The major problems are as follows: (1) when the concrete content of mud is high (8%), the slump loss of concrete is faster when concrete is mixed with water reducing agent or slump agent, and the slump of 60min is 0mm, and it has no construction performance. The slump loss of concrete can be effectively suppressed by using the three component of the water reducing agent - the slump agent - retarder. Loss, at higher temperature in summer, the 60min slump of concrete can be guaranteed to be above 180mm, and the construction performance is guaranteed. (2) the method of adding two times into the concrete slump material can guarantee the slump of the concrete 120min above 180mm and meet the construction requirements. The initial blending ratio of the slump material should be selected as 70% and 30% or 80% and 20%..

【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

【参考文献】