单掺/复掺碳纳米管和纳米二氧化钛硫铝酸盐水泥复合材料力学与自感知性能的影响

Effect of monodoped/multi-doped carbon nanotubes and nano-titanium dioxide on mechanical and self-sensing properties of sulfoaluminate cementitious composites

  • 摘要: 多壁碳纳米管(MWCNTs)和锐钛型纳米二氧化钛(NT)是制备自感知水泥基材料的两种优异纳米填料。与普通硅酸盐水泥比,硫铝酸盐水泥具有低碳、耐腐蚀和强度发展快等优点,作为胶凝材料时水泥基复合材料可获得更稳定的自感知性能。因此,本文使用锐钛型纳米二氧化钛和多壁碳纳米管分别以单掺和复掺的方式复合硫铝酸盐水泥砂浆,研究了复合导电填料类型对硫铝酸盐水泥复合材料3d力学、电学和自感知性能的影响规律,并结合SEM-EDS分析了影响机制。研究结果表明:NT可显著提高硫铝酸盐水泥复合材料的3d力学性能,单掺NT的试件抗压强度、抗折强度、劈拉强度和压缩韧性较不掺NT试件分别提高了28.36%、10.67%、47.76%和9.53%。单掺MWCNTs对复合材料的导电性能改善效果最为显著,直流电阻率和频率为100 kHz时的交流电阻率较对照组分别下降了46.91%和63.87%。复掺MWCNTs-NT对复合材料自感知性能改善效果最为明显:相比于对照组,在单调压缩荷载和劈拉荷载作用下,复掺MWCNTs-NT复合材料的最大电阻率变化率、应力灵敏度和应变灵敏度分别提高了235%、211%、313%和44%、65%、648%。通过SEM-EDS观察到,就密实程度而言,单掺NT组>对照组>复掺MWCNTs-NT组>单掺MWCNTs组;就导电网络变化的敏感度而言,复掺MWCNTs-NT组>单掺NT组>单掺MWCNTs组>对照组。

     

    Abstract: The multi-walled carbon nanotubes (MWCNTs) and anatase nano-titanium dioxide (NT) are excellent fillers for the preparation of self-sensing cement-based materials. Moreover, compared with ordinary Portland cement, sulfoaluminate cement has the advantages of low carbon, corrosion resistance and rapid strength development, and the cement-based material can obtain more stable self-sensing performance when used as a matrix. Therefore, this paper prepared sulfoaluminate cement mortar specimens using NT and MWCNTs in either single-addition or double-addition form. Then, the effects of different conductive fillers on the mechanical properties, electrical properties and self-sensing properties of the sulfoaluminate cementitious composites were studied at 3d, and the mechanisms were analyzed by SEM-EDS. The results show that the early mechanical properties of sulphoaluminate cementitious composites were significantly improved by adding NT. Compared to the control group, the compressive strength, flexural strength, splitting tensile strength, and compressive toughness of the cementitious composites with NT increased by 28.36%, 10.67%, 47.76%, and 9.53% , respectively. The single-addition of MWCNTs has the most significant effect on improving the conductivity. Compared with the control group, the DC resistivity and AC resistivity at a frequency of 100 kHz decreased by 46.91% and 63.87%, respectively. The double-addition of MWCNTs-NT has the most significant effect on improving the self-sensing properties of the sulfoaluminate cementitious composites. Compared with the control group, the maximum fractional change in resistivity, stress and strain sensitivity of the sulfoaluminate cementitious composites with MWCNTs-NT under monotonic compression load and splitting tensile load increased by 235%, 211%, 313%, and 44%, 65%, 648%, respectively. SEM-EDS showed that in terms of compactness, the mortar with NT> control group> mortar with MWCNTs-NT > mortar with MWCNTs, and in terms of the sensitivity of conductive network changes, the mortar with MWCNTs-NT > mortar with NT > mortar with MWCNTs.

     

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