碳纳米管接枝玄武岩纤维沥青胶浆的电愈合行为及机制

Electrically healing behavior and mechanism of asphalt mortar with carbon nanotube grafted basalt fibers

  • 摘要: 自愈合功能路面是当前道路工程研究的热点,其中通电发热是实现沥青路面自愈合的重要手段。为赋予沥青胶浆导电特性,以玄武岩纤维(BF)为连通基体,碳纳米管(CNTs)为导电相,运用化学接枝方法,提出了一种碳纳米管接枝玄武岩纤维(CNTs/BF)的制备工艺;通过电阻率、微观形貌、表面元素及官能团变化等表征试验,确定CNTs与BF最佳的接枝时间;设计CNTs/BF胶浆复数剪切模量和延度通电愈合试验,分析了CNTs/BF胶浆的通电愈合效果;联用红外热成像技术和数字图像散斑变形监测技术(DIC),分析了CNTs/BF胶浆的电愈合行为,揭示其愈合机制。研究结果表明:接枝3 h时CNTs/BF的电阻率下降6个数量级,碳(C)元素质量分数和Si—O—Si峰面积相比原样BF分别提高了23.96%和60.54%,说明CNTs接枝BF最佳时间为3 h;CNTs/BF胶浆的愈合指数均高于BF和CNTs胶浆,0.3wt%掺量时复数剪切模量愈合指数相比BF胶浆和CNTs胶浆分别提升了14.7%和18.6%,延度愈合指数分别提升了22.43%和16.76%,说明CNTs/BF最佳掺量为0.3wt%;红外热成像显示CNTs/BF胶浆的温度提升速率相比BF和CNTs胶浆分别提升123.53%和533.53%,说明CNTs/BF胶浆具有局部升温特性;DIC显示CNTs/BF胶浆在裂缝处愈合高差达1.86 mm,较BF和CNTs胶浆分别提升了77.99%和160.14%,裂缝呈现定向愈合,并基于此揭示了CNTs/BF胶浆的通电愈合机制。研究成果为CNTs/BF在道路工程的应用提供重要参考。

     

    Abstract: Self-healing functional pavement is the current hot spot of road engineering research, in which electrical healing plays a key role in enabling asphalt pavement to mend itself. To endow the asphalt mortar with conductive properties, a preparation process of carbon nanotubes grafted to basalt fibers (CNTs/BF) was proposed by using basalt fibers (BF) as the connecting matrix and carbon nanotubes (CNTs) as the conductive phase via a chemical grafting method. Characterization tests such as resistivity, micro-morphology, surface element and functional group changes were performed to determine the optimal grafting time of CNTs and BFs; Complex shear modulus and ductility electrical healing tests of CNTs/BF pastes were designed to analyze the energized healing effect of CNTs/BF pastes; Infrared thermography and digital image scattering deformation monitoring (DIC) were combined to analyze the electrical healing behavior of CNTs/BF pastes and reveal their healing mechanism. The results of the study show that: The resistivity of CNTs/BF at 3 h of grafting decreases by 6 orders of magnitude, the elemental mass fractions of C and the Si—O—Si peak area are increased by 23.96% and 60.54%, respectively, compared with the original sample BF, and 3 h is the optimal grafting time. The energized healing test shows that the healing indices of CNTs/BF pastes are higher than those of BF and CNTs pastes, and the complex shear modulus healing indices are improved by 14.7% and 18.6% and the ductility healing indices are improved by 22.43% and 16.76% at 0.3wt% doping compared with BF and CNTs pastes, respectively, and the optimal doping level is 0.3wt%. Infrared thermography shows that the temperature enhancement rates of CNTs/BF pastes are 123.53% and 533.53% higher compared to BF and CNTs pastes, respectively, indicating that CNTs/BF pastes have localized warming characteristics. DIC shows that CNTs/BF mastic have a healing height difference of 1.86 mm at the crack, which are 77.99% and 160.14% higher than that of BF and CNTs mastic, respectively, and the crack shows directional healing. Based on this, the energized healing mechanism of CNTs/BF mastic is revealed, and the research results provide an important reference for the application of CNTs/BF in road engineering.

     

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