热还原石墨烯改性水泥砂浆抗盐腐蚀性能研究

发布时间：2018-04-28 10:45

本文选题：热还原石墨烯 + 分散性能　；参考：《重庆交通大学》2017年硕士论文

【摘要】：目前,纳米材料作为水泥基材料的改性剂正逐渐应用于建筑材料中,而石墨烯作为一种二维纳米材料,具有巨大的比表面积、较高的表面能和较大的表面张力,表现出显著的纳米尺寸效应和表面效应,不仅可以明显改善水泥混凝土的韧性,还能提高其抗渗性能及耐久性能。本文选用热还原石墨烯为改性剂,通过宏观试验和微观测试相结合的方法,对水泥基材料的物理、力学及耐盐腐蚀性能方面进行研究,同时针对热还原石墨烯改善水泥砂浆抗盐腐蚀性能的作用机理进行深入探索。本文通过热还原法和超声波分散处理得到热还原石墨烯悬浊液(RGO),并利用XRD、SEM、TEM、AFM、FTIR、BET微观测试手段对其结构和性质进行表征;通过沉降法、丁达尔效应及吸光度试验,比较四种不同分散剂对热还原石墨烯在碱性水溶液中的分散作用;在此基础上,研究不同掺量热还原石墨烯对水泥净浆物理性能及水泥砂浆力学性能的影响,并结合微观测试手段研究其对水泥水化产物的调控作用;最后探究热还原石墨烯水泥砂浆在不同腐蚀环境(浓度为5%的NaCl、Na2SO4溶液)、不同外界环境(干湿循环、全浸泡)中的耐久性能及作用机理。研究表明,通过高温热还原法能将氧化石墨烯(GO)还原成石墨烯粉体,且转化率较高,还原较为彻底;保坍型聚羧酸系减水剂能够使热还原石墨烯均匀稳定地分散在碱性水溶液中,不发生沉积和团聚现象;在水泥基体中加入不同掺量的热还原石墨烯后,随着热还原石墨烯掺量的增加,水泥净浆标准稠度用水量、凝结时间有不同程度的增加,在保持用水量不变的条件下,水泥砂浆吸水率呈现增大趋势,流动度呈现下降趋势,毛体积密度呈现先变大后减小的趋势;此外,当热还原石墨烯掺量为0.9%时,水泥砂浆试件3d的抗折强度和抗压强度分别提高了18%和11%,28d的抗折强度和抗压强度分别提高了9.6%和5%;经全浸泡作用和干湿循环作用后,掺量为0.9%热还原石墨烯水泥砂浆试件的质量变化率最小,且水泥砂浆试件的力学强度变化率也最小。通过微观分析可知,掺量为0.9%热还原石墨烯水泥砂浆试内部结构更加致密,水化产物排布整齐有序且无明显腐蚀现象,表现出优异的耐盐腐蚀性能。
[Abstract]:At present, nanomaterials, as modifiers of cement-based materials, are gradually used in building materials, while graphene, as a two-dimensional nano-material, has a huge specific surface area, high surface energy and high surface tension. It can not only improve the toughness of cement concrete, but also improve its impermeability and durability. In this paper, the physical, mechanical and salt corrosion resistance of cement-based materials were studied by means of macroscopical test and microcosmic test. At the same time, the mechanism of improving the corrosion resistance of cement mortar by thermal reduction graphene is discussed. In this paper, thermal reduction method and ultrasonic dispersion treatment were used to obtain thermal reduced graphene suspensions (RGOA), and the structure and properties were characterized by means of microcosmic measurement of XRDX SEMMAM Tem Tem Tem FT-IR BET, and the sedimentation method, Dindal effect and absorbance test were used to characterize the structure and properties of RGOG. The effects of four kinds of dispersants on the dispersion of thermally reduced graphene in alkaline aqueous solution were compared, and the effects of different amounts of thermal reduced graphene on the physical properties of cement paste and the mechanical properties of cement mortar were studied. Finally, the paper studies the effect of thermal reduction graphene cement mortar in different corrosion environment (5% NaCl-Na _ 2SO _ 4 solution) and in different external environment (dry and wet cycle). The durability and the mechanism of action in the whole immersion. The results show that the graphene oxide can be reduced to graphene powder by high temperature thermal reduction, and the conversion rate is higher and the reduction is more thorough. The slump-preserving polycarboxylic acid superplasticizer can make the thermal reductive graphene dispersed in alkaline aqueous solution uniformly and stably without deposition and agglomeration. After adding different amounts of thermal reduced graphene into the cement matrix, With the increase of the content of heat-reducing graphene, the standard consistency and setting time of cement paste increase in varying degrees. Under the condition of keeping water consumption constant, the water absorption of cement mortar increases and the fluidity of cement mortar decreases. The bulk volume density increased first and then decreased. In addition, when the content of thermal reduced graphene was 0.9g, The flexural strength and compressive strength of cement mortar specimens increased by 18% and 11% and 28 days, respectively, and the flexural strength and compressive strength of cement mortar specimens increased by 9.6% and 5%, respectively. The change rate of mass and mechanical strength of cement mortar specimens with 0.9% thermal reduction of graphene cement mortar is the least and the change rate of mechanical strength of cement mortar specimens is also the smallest. Through microscopic analysis, it can be seen that the internal structure of the cement mortar with 0.9% thermal reduction of graphene is more compact, the hydration products are arranged orderly and have no obvious corrosion phenomenon, showing excellent salt corrosion resistance.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ177.62

【参考文献】