Self‐Sensing Cementitious Composites with Hierarchical Carbon Fiber‐Carbon Nanotube Composite Fillers for Crack Development Monitoring of a Maglev Girder

Abstract

In view of high‐performance, multifunctional, and low‐carbon development of infrastructures, there is a growing demand for smart engineering materials, making infrastructures intelligent. This paper reports a new‐generation self‐sensing cementitious composite (SSCC) incorporated with a hierarchically structured carbon fiber (CF)‐carbon nanotube (CNT) composite filler (CF‐CNT), which is in situ synthesized by directly growing CNT on CF. Various important factors including catalyst, temperature, and gas composition are considered to investigate their kinetic and thermodynamic influence on CF‐CNT synthesis. The reciprocal architecture of CF‐CNT not only alleviates the CNT aggregation, but also significantly improves the interfacial bonding between CF‐CNT and matrix. Due to the synergic and spatially morphological effects of CF‐CNT, that is, the formation of widely distributed multiscale reinforcement networks, SSCCs with CF‐CNTs exhibit high mechanical properties and electrical conductivity as well as excellent self‐sensing performances, particularly enhanced sensing repeatability. Moreover, the SSCCs with CF‐CNTs are integrated into a full‐scale maglev girder to devise a smart system for crack development monitoring. The system demonstrates high sensitivity and fidelity to capture the initiation of cracks/damage, as well as progressive and sudden damage events until the complete failure of the maglev girder, indicating its considerable potential for structural health monitoring of infrastructures.

Thermoelectric Power Factor of Boron‐Doped Carbon Nanotubes Reinforced Cementitious Composites

“…The enhanced contact conductivity of carbon nanotubes leads to increased conductivity of the composite. [ 72 ] In summary, the bridging effect of carbon nanotubes in cement matrix composites forms a conductive network, which makes the CNTs cement specimens have good electrical conductivity.…”

“…Excellent conductivity allows CNTs to bridge between cement, thereby improving the conductivity of the specimen. [ 72 ] The conductivity was 0.032, 0.20, and 0.44 s cm −1 for the doping of 0.25‐B‐CNTs (H 3 BO 3 : CNTs = 1:4) (0.76 at%) are presented in Figure 7b. Figure 7c compares the relationship between the boron atom content and the conductivity of CNTs for the same carbon nanotube content.…”

Preparation and characterization of graphene antibacterial phase change energy storage viscose fibers

“…The microPCM at a core/shell ratio of 9:1 stored up to 234.7 J/g heat energy, was leak proof, and thermally reliable over 100 heating and cooling cycles with efficient photothermal conversion up to 76.03% conversion efficiency. These studies 21,22 show that GO, as a modifier of PCMs, can not only effectively improve the thermal conductivity and enthalpy of phase change materials, but also improve the efficiency of light conversion as a photon trapping agent. But there is no relevant research on phase-change energy storage fiber and its application as antibacterial underwear, the addition of GO has the potential to increase the antibacterial properties of the fiber while improving its phasechange energy storage function.…”

Production and an advanced model for electrical conductivity of silicone rubber/carbon nanotube nanocomposites as outdoor insulator housing material

“…The marvelous CNTs' aspect relation and electrical conductivity can obtain excellent physical, mechanical, thermal characteristics, and electrical conductivity for the improvement of polymer performance. [20][21][22][23][24][25][26][27] These noteworthy properties have attracted the scientists' attention to many applications such as crack development monitoring, 28 smart high-speed rail infrastructures, 29 electromagnetic shielding, 30 aerospace structural design, 31 shape memory materials, 32 and high-voltage insulators. 10 When the CNT concentration reaches a specified rate, called the percolation point, the electrical conductivity of polymer-CNT nanocomposite is considerably upgraded and the polymeric medium is transferred from an insulator to a conductive material because the CNTs can then create a threedimensional (3D) conduction network, simplifying electron transportation.…”