熱還原石墨烯改性水泥砂漿抗鹽腐蝕性能研究
本文選題:熱還原石墨烯 + 分散性能; 參考:《重慶交通大學》2017年碩士論文
【摘要】:目前,納米材料作為水泥基材料的改性劑正逐漸應用于建筑材料中,而石墨烯作為一種二維納米材料,具有巨大的比表面積、較高的表面能和較大的表面張力,表現(xiàn)出顯著的納米尺寸效應和表面效應,不僅可以明顯改善水泥混凝土的韌性,還能提高其抗?jié)B性能及耐久性能。本文選用熱還原石墨烯為改性劑,通過宏觀試驗和微觀測試相結(jié)合的方法,對水泥基材料的物理、力學及耐鹽腐蝕性能方面進行研究,同時針對熱還原石墨烯改善水泥砂漿抗鹽腐蝕性能的作用機理進行深入探索。本文通過熱還原法和超聲波分散處理得到熱還原石墨烯懸濁液(RGO),并利用XRD、SEM、TEM、AFM、FTIR、BET微觀測試手段對其結(jié)構(gòu)和性質(zhì)進行表征;通過沉降法、丁達爾效應及吸光度試驗,比較四種不同分散劑對熱還原石墨烯在堿性水溶液中的分散作用;在此基礎(chǔ)上,研究不同摻量熱還原石墨烯對水泥凈漿物理性能及水泥砂漿力學性能的影響,并結(jié)合微觀測試手段研究其對水泥水化產(chǎn)物的調(diào)控作用;最后探究熱還原石墨烯水泥砂漿在不同腐蝕環(huán)境(濃度為5%的NaCl、Na2SO4溶液)、不同外界環(huán)境(干濕循環(huán)、全浸泡)中的耐久性能及作用機理。研究表明,通過高溫熱還原法能將氧化石墨烯(GO)還原成石墨烯粉體,且轉(zhuǎn)化率較高,還原較為徹底;保坍型聚羧酸系減水劑能夠使熱還原石墨烯均勻穩(wěn)定地分散在堿性水溶液中,不發(fā)生沉積和團聚現(xiàn)象;在水泥基體中加入不同摻量的熱還原石墨烯后,隨著熱還原石墨烯摻量的增加,水泥凈漿標準稠度用水量、凝結(jié)時間有不同程度的增加,在保持用水量不變的條件下,水泥砂漿吸水率呈現(xiàn)增大趨勢,流動度呈現(xiàn)下降趨勢,毛體積密度呈現(xiàn)先變大后減小的趨勢;此外,當熱還原石墨烯摻量為0.9%時,水泥砂漿試件3d的抗折強度和抗壓強度分別提高了18%和11%,28d的抗折強度和抗壓強度分別提高了9.6%和5%;經(jīng)全浸泡作用和干濕循環(huán)作用后,摻量為0.9%熱還原石墨烯水泥砂漿試件的質(zhì)量變化率最小,且水泥砂漿試件的力學強度變化率也最小。通過微觀分析可知,摻量為0.9%熱還原石墨烯水泥砂漿試內(nèi)部結(jié)構(gòu)更加致密,水化產(chǎn)物排布整齊有序且無明顯腐蝕現(xiàn)象,表現(xiàn)出優(yōu)異的耐鹽腐蝕性能。
[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.
【學位授予單位】:重慶交通大學
【學位級別】:碩士
【學位授予年份】:2017
【分類號】:TQ177.62
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