高保水性聚合物改性砂浆的研制及性能研究

发布时间：2018-03-12 18:54

本文选题：聚合物砂浆　切入点：羟丙基甲基纤维素醚　出处：《沈阳建筑大学》2015年硕士论文　论文类型：学位论文

【摘要】：考虑到建筑节能与环境保护,以加气混凝土砌块、小型混凝土空心砌块为代表的新型建材已成为现代建筑的墙体材料主要组成部分,但这些材料普遍具有吸水率高、干缩变形大的特点,墙体易开裂,要求罩面砂浆具有良好的保水性及韧性,减少由于基体吸水、变形而导致的墙面开裂、脱落现象。本论文从改善建筑砂浆保水性入手,探讨多种保水组分如羟丙基甲基纤维素醚、羧甲基纤维素钠、膨润土,矿物掺合料如粉煤灰、矿粉等对砂浆力学性能(抗压、折和粘结强度)、工作性能(保水性、稠度和流动度)以及抗开裂性能的影响规律,并通过SEM扫描电镜观察羟丙基甲基纤维素醚、羧甲基纤维素钠和膨润土这三种保水组分在砂浆中分散后的微观结构形态,分析保水性能的作用机理。研究结果表明:羟丙基甲基纤维素醚对于砂浆的粘结强度有较明显的改善,对抗折强度略有改善,但对于抗压强度几乎没有提高。当掺量在0.3%的时候,砂浆的粘结强度最高。砂浆的抗折强度在0.4%的掺量时达到最高值;羧甲基纤维素钠对砂浆的粘结强度有明显改善,但对抗压、折强度改善不明显。随着掺量的增加粘结强度逐渐提高,当掺量在0.3%时,砂浆的粘结强度最高;膨润土可以有效改善砂浆的抗折强度和粘结强度,对早期抗压强度有较明显提高,但对后期抗压强度改善不显著。膨润土掺量在5%时,砂浆的抗折强度和粘结强度出现最高值;粉煤灰对砂浆早期的抗压、折强度有损失,但在后期的强度有明显提高。对于粘结强度略有改善,掺入时要严格控制其替代量。粉煤灰替代量在24%时,砂浆28天的粘结强度出现最高值。而替代量在16%时,7天的粘结强度出现最高值。粉煤灰替代量在28%时,砂浆的28天抗压、折强度最高;矿粉对砂浆的早期抗折强度有损失,对于抗压强度和粘结强度都有较明显改善,所以矿粉和粉煤灰相似,考虑粘结强度的优化时要严格控制其替代量。矿粉替代量在24%时,砂浆的粘结强度出现最高值。矿粉替代量在32%左右时,砂浆的抗压、折强度最高;羟丙基甲基纤维素醚过多量添加,对于砂浆的工作性能改善不显著,甚至影响实验的操作,但是微量添加却可以很好的改善砂浆的工作性能,且最高保水率可达99.7%;羟丙基甲基纤维素醚、羧甲基纤维素钠、膨润土、粉煤灰和矿粉这五个组分对于砂浆的抗裂性能都有不同程度上的改善。只是矿物组分的掺合料对于砂浆的抗裂性改善效果要比聚合物组分的掺合料弱。从开裂性能上考虑,羟丙基甲基纤维素醚的开裂指数为31.2,要远优于其他组分,是改善砂浆开裂性能的最佳添加剂;通过SEM电镜扫描观察,聚合物的组分在砂浆中水解以后都会形成网或片状的膜结构穿插在砂浆中,而且聚合物的基团具有较高的吸水性,能很好的吸附水分,防止其流失,具有较高的保水能力。
[Abstract]:Taking into account building energy conservation and environmental protection, new building materials, represented by aerated concrete blocks and small concrete hollow blocks, have become a major component of wall materials in modern buildings, but these materials generally have high water absorption, The wall is easy to crack because of the large dry shrinkage deformation, which requires the covering mortar to have good water retention and toughness, to reduce the cracking and shedding of the wall due to the water absorption and deformation of the matrix. This paper begins with the improvement of the water-retaining property of the building mortar. This paper discusses the mechanical properties (compressive strength, flexural strength and bond strength) of various water-retaining components such as hydroxypropyl methyl cellulose ether, sodium carboxymethyl cellulose, bentonite, mineral admixtures such as fly ash, mineral powder, etc. The effects of consistency and fluidity on cracking resistance were studied by SEM scanning electron microscope. The microstructures of three water-retaining components, hydroxypropyl methyl cellulose ether, sodium carboxymethyl cellulose and bentonite, were observed by SEM scanning electron microscope. The mechanism of water retention was analyzed. The results showed that the adhesive strength and flexural strength of the mortar were obviously improved by hydroxypropyl methyl cellulose ether, and the flexural strength was slightly improved. However, the compressive strength of mortar is almost unchanged. When the content of cement is 0.3%, the bond strength of mortar is the highest, the flexural strength of mortar reaches the highest value at the content of 0.4%, and the bond strength of mortar is obviously improved by sodium carboxymethyl cellulose. However, the compressive strength and flexural strength were not improved obviously. The bond strength of mortar increased gradually with the increase of the content of bentonite, and the bond strength of mortar was the highest when the content was 0.3. Bentonite could effectively improve the flexural strength and bond strength of mortar, and bentonite could effectively improve the flexural strength and bond strength of mortar. The flexural strength and bond strength of mortar have the highest value when the content of bentonite is 5, and the compressive strength and flexural strength of fly ash are lost in the early stage of mortar, while the compressive strength of mortar in the early stage is improved obviously, but the improvement of compressive strength in the later stage is not obvious. But in the later stage, the strength has been improved obviously. The bond strength is slightly improved, and the substitution quantity of fly ash should be strictly controlled when it is mixed. When the substitution quantity of fly ash is 24, The bond strength of mortar appeared the highest value at 28 days, and the bond strength of 7 days after 16 days of substitution. When the replacement amount of fly ash was 28, the compressive strength of mortar was 28 days and the flexural strength was the highest; the mineral powder had a loss on the early flexural strength of mortar. The compressive strength and bond strength are obviously improved, so the mineral powder is similar to fly ash. When considering the optimization of bond strength, the substitution quantity of mineral powder should be strictly controlled. The bond strength of mortar has the highest value. When the substitution of mineral powder is about 32%, the compressive strength and flexural strength of mortar are the highest, and the addition of hydroxypropyl methyl cellulose ether is not significant to the performance of mortar, and even affects the operation of experiment. However, microaddition can improve the performance of mortar, and the highest water retention rate can reach 99.7%; hydroxypropyl methyl cellulose ether, carboxymethyl cellulose sodium, bentonite, hydroxypropyl methyl cellulose ether, carboxymethyl cellulose sodium, bentonite, hydroxypropyl methyl cellulose ether, carboxymethyl cellulose sodium, The five components of fly ash and mineral powder have improved the crack resistance of mortar to some extent, but the effect of the admixture of mineral component is weaker than that of the admixture of polymer component. The cracking index of hydroxypropyl methyl cellulose ether is 31.2, which is much better than other components, and is the best additive to improve the cracking property of mortar. After hydrolysis of polymer in mortar, the polymer components will form a network or a membrane structure in the mortar, and the polymer group has a high water absorption, good adsorption of water, prevent its loss, and has a higher water retention capacity.
【学位授予单位】：沈阳建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ177.6

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