聚羧酸系减水剂与可溶性碱对水泥性能的影响研究

发布时间：2018-04-28 05:32

本文选题：聚羧酸系减水剂 + 可溶性碱　；参考：《安徽建筑大学》2015年硕士论文

【摘要】：聚羧酸系减水剂(Polycarboxylate-based Superplasticizer,简称PC)是由含有羧酸的不饱和单体以及其他单体共聚而成的,是一类具有特定结构和性能的聚合物的总称。这类减水剂的共同特点是主链中含有一定数量的羧基官能团,分子结构呈线形、梳状或多枝状,具有高减水率、优异的保塑性能,且能使混凝土具有良好的物理力学性能。通过自由基聚合合成了一种新型聚醚型聚羧酸减水剂(PC-1),将其与聚酯型聚羧酸减水剂(PC-2)进行对比研究,主要比较这两类PC与水泥的相容性。通过掺加K2CO3来改变水泥浆体中可溶性碱含量,研究可溶性碱含量对掺不同类型PC的水泥净浆流动性能、颗粒表面zeta电位、水化进程、以及其他性能的影响。主要研究工作分述如下:(1)聚醚型聚羧酸减水剂的合成研究:以烯丙基聚乙二醇(APEG)、烯丙基磺酸钠(SAS)、丙烯酸(AA)为主要原料,合成了一种新型聚醚型PC。分别研究了引发剂用量、单体比例、反应温度、聚合时间等因素对聚合产物分散性能的影响。通过进一步正交试验确定了最佳合成工艺参数为:n(AA):n(APEG):n(SAS)=18:9:13,引发剂用量为1.5%,反应温度为80℃,聚合时间为8h。(2)可溶性碱对PC与水泥相容性的影响:比较不同掺量的PC-1和PC-2对水泥净浆流动性能的影响,分析二者对水泥颗粒的分散作用机理。通过掺加K2CO3来改变浆体可溶性碱含量,研究可溶性碱含量对掺不同类型PC的水泥净浆流动性能的影响。结果表明:PC-1与水泥的相容性要明显优于PC-2,其饱和掺量点更低,能使浆体初始流动度高,且流动度经时损失小。当PC-1或PC-2掺量低于其饱和掺量时,适当增加可溶性碱含量对PC-1与水泥相容性的影响不大,却能明显提高PC-2与水泥的相容性,增强浆体的流动性能。(3)可溶性碱对掺不同类型PC的水泥水化反应的影响:研究了可溶性碱与PC的共同作用对水泥水化热的影响,并分别对水化产物进行了XRD和SEM分析。结果表明:掺PC-1或PC-2都能使水泥水化放热速率增大,适当增加可溶性碱可以降低掺PC-1或PC-2水泥的水化放热速率以及放热量。PC-1和PC-2都能促进水泥的早期水化,增加可溶性碱含量都能在一定程度上加快掺PC-1或PC-2的水泥水化进程,能使硬化水泥结构更加致密,有利于水泥石早期强度的发展。(4)PC与可溶性碱对水泥性能的影响:研究了可溶性碱与PC的共同作用对水泥凝结时间、水泥石孔径分布以及硬化后水泥石抗折、抗压强度的影响。结果表明:当PC-1掺量较低时,少量可溶性碱对浆体有缓凝效应,当PC-1掺量较高时,可溶性碱对浆体则表现出一定的促凝效应;而对于掺PC-2的浆体而言,可溶性碱对浆体有很强的促凝效应。PC-1能使水泥石最可几孔径增大,可溶性碱能使掺PC-1的水泥石孔容大幅下降,有利于水泥石强度的发展;而PC-2对水泥石孔径分布影响不大,可溶性碱对掺PC-2的水泥石强度的提高也不明显。当PC-1或PC-2的掺量为0.04%,可溶性碱掺量为0.36%~0.48%时,有利于水泥石抗折、抗压强度的提高。本论文的研究工作揭示了可溶性碱对不同类型PC与水泥相容性的影响规律,拓宽了PC的应用范围,对实际工程建设有一定的指导意义。
[Abstract]:Polycarboxylate-based Superplasticizer (PC) is formed by the copolymerization of unsaturated monomers and other monomers containing carboxylic acids. It is the general name of a class of polymers with specific structures and properties. The common characteristic of this kind of water reducing agent is that the main chain contains a certain number of carboxyl functional groups and the molecular structure is linear. A new polyether polycarboxylic acid water reducer (PC-1) was synthesized through free radical polymerization. The ratio of the polycarboxylic acid water reducing agent (PC-2) to polyester type polycarboxylic acid water reducing agent (PC-2) was studied, and the compatibility of the two kinds of PC with cement was compared. The content of soluble alkali in cement paste was changed by adding K2CO3, and the effects of soluble alkali content on the flow performance, zeta potential, hydration process and other properties of cement mixed with different types of PC were studied. The main research work is as follows: (1) synthesis of polyether polycarboxylic acid water reducing agent: allyl polyethylene glycol (APEG) A new polyether type PC. was synthesized with sodium allyl sulfonic acid (SAS) and acrylic acid (AA) as the main raw material. The influence of the dosage of initiator, monomer ratio, reaction temperature and polymerization time on the dispersion properties of the polymerization products was studied. The optimum synthetic parameters were determined by further orthogonal test: n (AA): n (APEG): n (SAS) =18:9:13. The dosage of the agent is 1.5%, the reaction temperature is 80 C, the polymerization time is 8h. (2) and the effect of soluble alkali on the compatibility of PC and cement: the effect of different dosage of PC-1 and PC-2 on the flow performance of cement paste is compared, and the dispersing mechanism of the cement particles is analyzed. The soluble alkali content of the slurry is changed by adding K2CO3, and the soluble alkali content is studied. The effect of quantity on the flow performance of cement paste with different types of PC shows that the compatibility of PC-1 and cement is obviously better than that of PC-2, and its saturation content is lower, and the initial flow degree of the slurry is higher and the time loss of flow is small. When the content of PC-1 or PC-2 is lower than its saturated content, the compatibility of soluble alkali content is appropriately increased to the compatibility of PC-1 with cement. The effect of sex is not significant, but it can obviously improve the compatibility of PC-2 with cement and enhance the flow performance of the slurry. (3) the effect of soluble alkali on the hydration of cement mixed with different types of PC: the effect of the joint action of soluble alkali and PC on the hydration heat of cement, and the analysis of the hydration products by XRD and SEM respectively. The results show that PC-1 or P is added. C-2 can increase the heat release rate of cement hydration, the appropriate increase of soluble alkali can reduce the hydration heat rate of PC-1 or PC-2 cement, and the heat release.PC-1 and PC-2 can promote the early hydration of cement. The increase of soluble alkali content can accelerate the hydration process of PC-1 or PC-2 cement to a certain extent, and can make the hardened cement structure more structure. In addition, it is beneficial to the development of early strength of cement stone. (4) the effect of PC and soluble alkali on the performance of cement: the effect of the joint action of soluble alkali and PC on the cement setting time, pore size distribution of cement stone and the compressive strength of cement stone after hardening. The results show that a small amount of soluble alkali can have a small amount of soluble alkali to the slurry when the amount of PC-1 is low. When the content of PC-1 is high, the soluble alkali has a certain accelerating effect on the slurry when the content of the mixture is high. For the slurry with PC-2, the soluble alkali has a strong effect on the slurry,.PC-1 can increase the pore size of the cement stone, and the soluble alkali can greatly decrease the cement Shi Kongrong content of the PC-1, which is beneficial to the development of the strength of cement stone. And PC-2 has little effect on the pore size distribution of cement stone, and the increase of the strength of the cement stone with PC-2 is not obvious. When the dosage of PC-1 or PC-2 is 0.04% and the soluble alkali content is 0.36%~0.48%, it is beneficial to the flexural strength and the increase of the compressive strength of the cement stone. The influence rule of sex broadens the application scope of PC, and has certain guiding significance for practical engineering construction.

【学位授予单位】：安徽建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ172.1

【参考文献】