高分子水泥混凝土添加剂的合成、机理及应用研究

发布时间：2018-01-04 07:22

本文关键词：高分子水泥混凝土添加剂的合成、机理及应用研究　出处：《东南大学》2017年博士论文　论文类型：学位论文

【摘要】：在我国基础建设迅速发展,大力开展节能减排,建设绿色资源节约型,环境友好型社会的条件下,水泥助磨剂和混凝土减水剂技术迅速发展。在水泥工业生产中,水泥粉磨是能耗最高的过程,大约有97%的能量消耗在无效的热能中而白白浪费掉,而水泥助磨剂在节能降耗方面效果显著。但是在应用过程中发现:传统水泥助磨剂的产品质量的不稳定问题,与混凝土材料的相容性问题以及混凝土耐久性问题没有得到很好的解决,也缺乏充分的研究。此外,由于地区差异和天然材料的不断匮乏,混凝土集料砂石中的高含泥量和高石粉含量严重限制聚羧酸减水剂的性能发挥,给混凝土施工带来极大困难和安全隐患。一直以来,水泥助磨剂和混凝土减水剂被分开独立研究,造成的弊端被逐渐显现出来。因此,开发一种高分子水泥混凝土添加剂(PCCA),使其同时具备良好的水泥助磨性能与优异的"抗泥"效果,有助于从根本上解决传统水泥助磨剂和聚羧酸减水剂存在的问题。本论文的主要研究内容:本文以丙烯酰胺、马来酸酐、乙烯基聚醚(分子量:380,600,1200,2400)为聚合单体,巯基乙酸为链转移剂,双氧水和维生素C为引发剂(摩尔比为4.5:1),研究了反应温度、反应时间、单体配比及引发剂用量对PCCA助磨效果的影响。PCCA的最佳合成工艺条件为:反应温度为30～35℃,反应时间为3.5h,引发剂用量为20%,马来酸酐用量为20%,丙烯酰胺的用量为9%。为研究分子结构变化对性能的影响,通过分子结构设计,合成出不同基团构成和相对分子量大小的PCCA(PGA-1～PGA-7),并提出PCCA的自由基聚合机理。本文选择粉磨水泥的比表面积,粒度分布和流动性作为PCCA水泥助磨效果的评价指标。研究了 PCCA分子结构,掺量,粉磨时间对水泥助磨效果的影响。PCCA表现出优异的助磨效果,粉磨水泥的团聚现象消失,流动性增加,颗粒粒度分布变窄以及水泥比表面积明显增大。研究发现:PCCA分子结构中阴离子基团和非离子基团摩尔比存在最佳点,非离子的支链长度越短,相对分子质量越小,PCCA的助磨效果越好。从实验结果推理出PCCA的水泥助磨机理为化学吸附,加速开裂,电荷消除和表面润滑共同作用的结果。本文通过测试水泥凝结时间、水化放热速率、水化初期电导率、水化产物变化及水泥胶砂强度,研究PCCA对水泥水化的影响。结果表明:PCCA延长了水泥的初凝和终凝时间。XRD、SEM和MIP测试表明:PCCA促进水泥后期水化产物的生成,明显降低水泥石微观孔隙中有害孔和少害孔比例。随着PCCA分子结构中阴离子基团比例的增加,水泥净浆流动度先增加后减小,水泥胶砂强度逐渐增大。在混凝土减水率测试中,脂肪族减水剂和萘系减水剂在1.4%掺量下,减水率同为16%;聚羧酸减水剂和PCCA在0.5%掺量下减水率分别为31.5%和16.5%。在PCCA的抗泥性混凝土实验中发现:PCCA对高岭土和粘土有很好的"屏蔽"作用。PCCA以吸附-插入-分散-包裹等不同方式改善了混凝土的活易性和保塌性。在粘土含量为6%的河沙中掺入不同分子量大小的PCCA,研究发现分子量最小的PCCA对粘土的"屏蔽"效果最佳。在集料中加入6%的粘土和石粉的混凝土实验中发现,与单独掺入聚羧酸减水剂的空白样相比,掺入PCCA后,混凝土的初始坍落度和扩展度增大,特别是1h混凝土流动性损失很小,PCCA表现出非常优异的保坍性能,明显优于相同条件下市售的抗泥剂丙三醇和聚乙二醇(300)。同时研究发现PCCA的加入方式对其抗泥效果影响较大,PCCA与聚羧酸减水剂同时掺入时,混凝土的初始流动性最好,后于聚羧酸减水剂掺入时,混凝土的流动性保持性能最好。从混凝土抗冻融、抗硫酸盐侵蚀和抗氯离子渗透三个方面研究了 PCCA对混凝土耐久性的影响。抗冻融结果表明,由于PCCA的引气作用,掺PCCA混凝土试件表现出更好的抗冻融破坏能力。抗硫酸盐侵蚀研究表明,随着PCCA掺量的增加,混凝土试件的质量损失逐渐降低,动弹性模量逐渐增大。采用电通量法测试混凝土试件的电通量表明PGA-1能提高混凝土的抗氯离子渗透能力。此外,从水泥标准稠度用水量、水泥凝结时间、净浆流动度、混凝土初始和经时流动性、混凝土强度和混凝土微观结构分析等角度系统研究了 PCCA与木聚脂肪族减水剂(由纸浆黑液与脂肪族减水剂接枝共聚制备)、脂肪族减水剂、萘系减水剂和聚羧酸减水剂的相容性。实验结果表明,在与各混凝土外加剂复掺使用时,PCCA能够优先吸附在水泥胶体表面,降低了水泥标准稠度用水量,延长了水泥凝结时间,改善了各减水剂的应用效果,表现出良好的相容性。本论文的主要创新成果:本文选择高分子水泥混凝土添加剂为研究课题,开发出一种集水泥助磨剂和混凝土减水剂功能为一体的高分子水泥混凝土添加剂,确定了 PCCA的合成工艺,在性能上实现优异的水泥助磨效果和在高含泥量混凝土中的良好的抗泥效果;实现依据产品性能要求进行PCCA的分子结构设计并揭示出自由基聚合机理;明确了高分子聚合物中分子量、功能基团和支链长度与水泥助磨效果的对应关系,提出PCCA的水泥助磨机理为化学吸附,加速开裂,电荷消除和表面润滑共同作用的结果;通过研究PCCA分子结构对高含泥量/含石粉量混凝土性能的影响,提出PCCA的"抗泥"原理。
[Abstract]:In the rapid development of China's infrastructure construction, vigorously carry out energy-saving emission reduction, green building a resource-saving, environment-friendly society under the condition of cement grinding agent and concrete reducing agent technology. The rapid development in the cement industry, cement grinding process is the highest energy consumption, there are about 97% of the energy consumed in invalid heat and waste, and cement grinding aids in the energy saving effect is remarkable. But in the application process: the traditional cement grinding agent product quality is not stable, and solve the problem of compatibility of concrete and concrete durability problems have not been very good, but also the lack of adequate research. In addition, due to the regional differences and the increasing scarcity of natural materials, concrete aggregate sand in high mud content and high stone powder content seriously limits the performance of polycarboxylate superplasticizer play, bring convenience to the concrete construction Great difficulty and safety hazard. Since the cement grinding agent and concrete superplasticizer were researched independently, the abuse was gradually revealed. Therefore, the development of a polymer cement concrete additive (PCCA), which has good grinding performance and cement and excellent anti mud effect, have to fundamentally solve the traditional cement grinding agent and water reducing agent problems exist. The main contents of this paper: in this paper, acrylamide, maleic anhydride, vinyl ether (molecular weight: 38060012002400) as the monomer, thioglycolic acid as chain transfer agent, hydrogen peroxide and vitamin C as initiator (molar ratio 4.5:1), reaction temperature, reaction time research, ratio of monomer and initiator on PCCA grinding effect.PCCA the best synthesis conditions are: reaction temperature is 30 to 35 DEG C, the reaction time is 3.5H, the dosage of initiator 20%, dosage of maleic anhydride acrylamide was 20%, dosage of 9%. in order to study the effect of molecular structure on the properties of change, through molecular structure design, synthesis of different groups and PCCA molecular weight (PGA-1 ~ PGA-7), and put forward the PCCA free radical polymerization mechanism. The grinding of cement specific surface area the particle size distribution, and liquidity as the evaluation index to help PCCA cement grinding effect. To study the molecular structure of PCCA, dosage, grinding time of cement grinding effect.PCCA showed excellent grinding effect, disappear agglomeration of cement grinding, increased mobility, narrow particle size distribution and specific surface area of cement obviously increases. It is found that the PCCA in the molecular structure of anionic groups and non ionic groups of molar optimum point, nonionic branched chain length and the molecular weight is small, PCCA from grinding effect better. The experimental results infer PCCA cement grinding mechanism is chemical adsorption, accelerated cracking, interaction charge elimination and surface lubrication results. Through testing the setting time, hydration rate, hydration initial conductivity, hydration products change and strength of cement mortar, the effects of PCCA on cement hydration. Show that PCCA extended the cement initial setting and final setting time of.XRD, SEM and MIP test showed that PCCA promote the formation of the late cement hydration products, reduce cement stone pore harmful hole and less harm. With the increase of hole ratio of PCCA molecular structure in the anionic group ratio, cement paste fluidity first increased and then decreased, the strength of cement mortar increased gradually. In the water reducing rate of concrete test, aliphatic superplasticizer and naphthalene superplasticizer at the dosage of 1.4%, the water reducing rate is 16%; polycarboxylate superplasticizer and PCCA water reducing rate at the dosage of 0.5% 31.5% and 16.5%. respectively in PCCA anti mud concrete experiment: PCCA of kaolin and clay are the "shielding" effect to.PCCA adsorption - Insert - dispersion - wrapped in different ways to improve the concrete workability and live security collapse. In the different molecular weight of PCCA was 6% of the river the sand mixed with clay content, the study found that the molecular weight of the smallest PCCA of clay "shielding" effect is the best. The 6% clay concrete and stone powder in the aggregate in compared with the incorporation of polycarboxylate superplasticizer blank sample, the incorporation of PCCA after the initial concrete slump and expansion the degree of increase, especially the loss of fluidity of 1H concrete is very small, PCCA showed a slump with very excellent performance, superior anti sediment agent glycerol and polyethylene glycol under the same conditions of commercially available (300). At the same time, it is found that the effect of PCCA on the way to join the anti sediment effect greatly, PCCA polycarboxylate superplasticizer and at the same time mixing, the initial fluidity of concrete, after polycarboxylate superplasticizer incorporation, the fluidity of concrete to maintain the best performance. The concrete freeze-thaw resistance, sulfate resistance and resistance to chloride ion penetration of the three aspects of the effects of PCCA on the durability of concrete frost resistance. The results show that the air entraining effect of PCCA, PCCA concrete specimens showed better resistance to freeze-thaw damage. Anti sulfate corrosion research shows that with the increase of PCCA content, the mass loss decreased concrete dynamic elastic modulus increases gradually. The electric flux test of concrete electric flux parts show PGA-1 can improve the resistance of concrete to chloride ion penetration. In addition, water from the cement standard consistency, setting time, fluidity, fluidity and the initial concrete, concrete strength and concrete The microstructure analysis has investigated the PCCA and wood poly (aliphatic superplasticizer agent prepared by graft copolymerization by reducing pulp black liquor and aliphatic), aliphatic superplasticizer, compatibility of naphthalene superplasticizer and polycarboxylate superplasticizer. The experimental results show that with the concrete admixture composition is used, PCCA can be preferentially adsorbed in the cement colloid surface, reducing the cement standard consistency water, prolong the setting time of cement, improve the application effect of the superplasticizer, showed good compatibility. The main innovation points of this paper: This paper choose polymer cement concrete additive for research, developed a set of concrete and cement grinding agent water reducing functions of the polymer cement concrete additive, the synthesis process of PCCA, achieve excellent effect in cement grinding and high mud content in concrete is good in performance. The anti sediment effect; molecular structure design of PCCA based on product performance requirements and reveals the free radical polymerization mechanism; clear molecular polymer content in the corresponding relationship between functional groups and the length of the branched chain and cement grinding effect, proposed PCCA cement grinding mechanism is chemical adsorption, accelerated crack interaction, charge elimination and the surface lubrication results; by studying the effects of molecular structure on PCCA with high content of clay / powder containing properties of concrete, puts forward PCCA "anti mud" principle.

【学位授予单位】：东南大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TQ172.463;TU528.042

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