氧化石墨烯对多壁碳纳米管掺配水泥砂浆强度、压敏性能与微观结构的影响

Effect of graphene oxide on mechanical properties, piezoresistivity and microstructure of cement mortar blended with multi-walled carbon nanotubes

  • 摘要: 多壁碳纳米管(MWCNTs)对水泥基材料可起到增强增韧的作用。但MWCNTs易在水泥浆体中团聚,目前国内外对如何深化氧化石墨烯(GO)在水泥浆体中分散MWCNTs的报道较为罕见。采用吸光度试验考察了木质素磺酸钠(MN)存在时,GO对MWCNTs在模拟水泥水化孔隙液的饱和氢氧化钙溶液(CH)中分散性能的影响,并研究了GO对MWCNTs掺配砂浆力学性能、电热性能、电阻率及压敏性的影响。吸光度测试表明MN、GO、MWCNTs质量比为3∶1∶9时,MWCNTs分散达到最佳,力学性能测试表明当MWCNTs、GO最佳掺量分别为0.45wt%、0.05wt%时,28天抗折抗压强度比相同MWCNTs掺量的试件分别提高了27.3%、20.9%,电阻率降低了18.2%,电阻变化率提高了72.6%。微观结构测试表明GO能进一步促进MWCNTs在水泥基材料中分散,促进水泥水化进程,密实了水泥石结构,对MWCNT掺配砂浆强度有协同增长作用,提高了压敏性能。本研究采用GO分散MWCNT的方法可扩展到其他碳基纳米增强剂,并为发展自感知智能化水泥基材料提供了一种新的途径。

     

    Abstract: Multi-walled carbon nanotubes (MWCNTs) can strengthen and toughen cement-based materials. However, MWCNTs tend to agglomerate in cement paste. Up to now, there are few reports about how to improve the dispersion of MWCNTs by graphene oxide (GO) in cement paste. The effect of GO on the dispersion of MWCNTs in saturated calcium hydroxide solution (CH) used for simulated cement pore solution in the presence of sodium lignosulfonate (MN) was investigated by absorbance test, and the effects of GO on the mechanical properties, electrothermal properties, resistivity and pressure sensitivity of mortars containing MWCNTs were studied. The absorbance test shows that when the mass ratio of MN, GO and MWCNTs is 3∶1∶9, the dispersion of MWCNTs reaches the best. The mechanical properties test shows that when the optimal contents of MWCNTs and GO are 0.45wt% and 0.05wt% by the cement mass respectively, the 28 days flexural and compressive strength of the specimens are increased by 27.3% and 20.9%, the resistivity is reduced by 18.2%, and the resistance change rate is increased by 72.6%. The microstructure test shows that GO could further promote the dispersion of MWCNTs in cement-based materials, accelerate the hydration process of cement, densify the structure of cement paste. The synergy of GO and MWCNT increases the mechanical and durability and self-sensing properties of the cement mortar. In this study, the method to disperse MWCNT assisted by GO can be further extended to other carbon-based nano-reinforcing agents, and provides a new way for the development of self-sensing and intelligent cement-based materials.

     

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