Maimaitituersun Nueraili, Wang Jing, Wang Danna, Ning Zuojun
School of Transportation, Kashi University, Kashi 844000, China.
Tianjin Urban Road Facility Inspection Center, Tianjin 300190, China.
Materials (Basel). 2025 Apr 16;18(8):1830. doi: 10.3390/ma18081830.
Carbon fibers, with high modulus of elasticity, tensile strength, and electrical conductivity, can modify the mechanical and electrical properties of cementitious composites, facilitating their practical application in smart infrastructure. This study investigates the effects of carbon nanofibers (including carbon nanotubes, a special type of carbon nanofibers) and micron carbon fibers with different aspect ratios and surface treatments on the uniaxial tensile and electrical properties of cementitious composites. The results demonstrate that appropriate carbon fiber doping markedly improves the uniaxial tensile strength of cementitious composites, with enhancement effects following a gradient trend based on a geometric scale: carbon nanotubes (CNTs) < carbon nanofibers (CNFs) < short-cut carbon fibers (CFs). Hydroxyl-functionalized multi-walled carbon nanotubes (MWCNTs) form continuous conductive networks due to surface active groups (-OH content: 5.58 wt.%), increasing the composite's electrical conductivity by two orders of magnitude (from 3.56 × 10 to 2.74 × 10 Ω·cm), with conductivity enhancement becoming more pronounced at higher doping levels. Short-cut CFs also improve conductivity, with longer fibers (6 mm) exhibiting a 12.4% greater reduction in resistivity. However, exceeding the percolation threshold (0.5-1.0 vol.%) leads to limited conductivity improvement (<5%) and mechanical degradation (8.7% tensile strength reduction) due to fiber agglomeration-induced interfacial defects. This study is a vital reference for material design and lays the groundwork for self-sensing cementitious composites.
碳纤维具有高弹性模量、抗拉强度和导电性，能够改善水泥基复合材料的力学和电学性能，有助于其在智能基础设施中的实际应用。本研究调查了不同长径比和表面处理的碳纳米纤维（包括碳纳米管，一种特殊类型的碳纳米纤维）和微米级碳纤维对水泥基复合材料单轴拉伸和电学性能的影响。结果表明，适当的碳纤维掺杂显著提高了水泥基复合材料的单轴抗拉强度，增强效果遵循基于几何尺度的梯度趋势：碳纳米管（CNTs）<碳纳米纤维（CNFs）<短切碳纤维（CFs）。羟基官能化多壁碳纳米管（MWCNTs）由于表面活性基团（-OH含量：5.58 wt.%）形成连续导电网络，使复合材料的电导率提高了两个数量级（从3.56×10到2.74×10Ω·cm），在较高掺杂水平下电导率增强更为明显。短切CFs也能提高电导率，较长的纤维（6 mm）表现出电阻率降低12.4%。然而，超过渗流阈值（0.5-1.0 vol.%）会导致电导率改善有限（<5%）和力学性能下降（抗拉强度降低8.7%），这是由于纤维团聚引起的界面缺陷所致。本研究为材料设计提供了重要参考，并为自传感水泥基复合材料奠定了基础。
