纳米级氧化硅和碳纤维复合砂浆的制备和性能

发布时间：2018-02-23 19:25

本文关键词： 纳米二氧化硅纳米碳纤维砂浆制备工艺性能　出处：《大连理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：纳米技术的发展为水泥基材料的可持续发展提供了新的动力。纳米材料可以在纳米尺度上对水泥基材料进行改性,既包括改善水泥基材料的力学性能也包括赋予水泥基材料功能特性。本文在纳米氧化硅(NS)复合砂浆的制备工艺与性能、纳米碳纤维(CNF)复合砂浆的制备工艺与性能研究的基础上,探索了NS和CNF复合砂浆的性能及影响因素,主要研究内容如下：1 比较了疏水纳米二氧化硅(SS)复合砂浆的机械搅拌法和研磨法制备工艺,以及亲水纳米二氧化硅(QS)复合砂浆的机械搅拌法、研磨法和超声法制备工艺；制备了0.5%、1.0%、2.0%、3.0%、4.0%、5.0%掺量的SS复合砂浆和QS复合砂浆,并对复合砂浆的抗折强度、抗压强度及微观结构和性能进行了测试。研究结果表明,QS可细化氢氧化钙、促进水泥水化和降低氢氧化钙的择优取向,适宜掺量的QS可提高砂浆的抗折强度和抗压强度；SS对砂浆无增强效果。2 以砂浆3d、28d的抗折和抗压强度为评价指标确定了CNF复合砂浆的减水剂掺量和超声时间分别为减水剂与CNF的质量比为1和30mmin；在此基础上,制备了CNF掺量为0.05%、0.10%、0.15%、0.20%、0.40%、0.60%和0.80%的复合砂浆并测试了抗折和抗压强度,电阻率及微观结构和性能。研究结果表明,CNF可促进水泥水化但是会提高氢氧化钙的择优取向,适宜掺量的CNF可提高复合砂浆的抗折强度、抗压强度和电导率。3制备了2%、3%QS分别与0.05%、0.10%和0.15%CNF复掺的砂浆并测试了抗折和抗压强度以及受弯荷载下的电阻率变化规律,由于砂浆中存在较大裂纹、CNF呈现团聚状态,复掺QS和CNF没有达到单掺时的力学增强效果；3%QS+CNF的复合砂浆在受弯载荷下的电阻率变化率大于2%QS+CNF的复合砂浆。4通过正交试验分析了水胶比、砂灰比、QS掺量、CNF掺量四个因素对QS+CNF复合砂浆力学性能和电学性能的影响。研究结果表明,对力学性能影响最显著的因素是水灰比；提高砂浆基体的密实度并综合运用超声、化学分散和掺加硅灰辅助分散可制备力学性能优异的QS+CNF复合砂浆；对电阻率影响最显著的因素是纳米碳纤维掺量;最终获得了最佳因素水平组合。
[Abstract]:The development of nanotechnology provides a new impetus for the sustainable development of cement-based materials. Nanomaterials can modify cement-based materials at nanometer scale. It includes improving the mechanical properties of cement-based materials as well as endowing the functional properties of cement-based materials. In this paper, the preparation process and properties of nano-silica NS-based composite mortar, and the preparation technology and properties of nano-carbon fiber reinforced polymer composite mortar are studied in this paper. The properties and influencing factors of NS and CNF composite mortar were explored. The main contents of the study were as follows: 1. The preparation process of hydrophobic nano-silica composite mortar was compared by mechanical stirring method and grinding method. The mechanical agitation, grinding and ultrasonic preparation of hydrophilic nano-silica / QS composite mortar were also carried out, and the SS composite mortar and QS composite mortar were prepared, and the flexural strength of the composite mortar was also studied. The compressive strength, microstructure and properties were tested. The results show that QS can refine calcium hydroxide, promote cement hydration and reduce the preferred orientation of calcium hydroxide. The appropriate dosage of QS can improve the flexural strength and compressive strength of mortar. 2. With the flexural strength and compressive strength of CNF composite mortar as evaluation indexes, the quantity of water reducer and ultrasonic time of CNF composite mortar are determined as follows: 2. The mass ratio of water reducer to CNF is 1 and 30 min. The composite mortar of 0.20% and 0.40% and 0.40% and 0.40% of CNF was prepared, and the flexural and compressive strength, resistivity, microstructure and properties were tested. The results show that CNF can promote hydration of cement but improve the preferred orientation of calcium hydroxide. The flexural strength of composite mortar can be improved by adding appropriate amount of CNF. The compressive strength and electrical conductivity of 3QS are prepared. 3QS and 0.05% 0.10% and 0.15% respectively. The flexural and compressive strength and the change rule of resistivity under bending load are tested. Due to the existence of large cracks in mortar, CNF exhibits agglomeration. The mechanical strengthening effect of mixed QS and CNF was not achieved when the composite mortar was mixed with QS and CNF. The ratio of water to binder was analyzed by orthogonal test for composite mortar with QS CNF under flexural load. The change rate of resistivity of composite mortar was greater than 2 QS CNF, and the ratio of water to binder was analyzed by orthogonal test. The effects of four factors on the mechanical and electrical properties of QS CNF composite mortar are studied. The results show that the most significant influence factors on the mechanical properties are water-cement ratio, improving the compactness of mortar matrix and synthetically using ultrasonic, The QS CNF composite mortar with excellent mechanical properties can be prepared by chemical dispersion and silica fume assisted dispersion. The most significant factor affecting the resistivity is the content of carbon nanofibers, and the best level combination of factors is obtained.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ177.67

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