Electrical and microstructural characterization of carbon nanotube-carbon fiber added cementitious conductive surface coating

Abstract

In contrast to the traditional methods of directly adding conductive fillers to the cement matrix in the development of heatable conductive concrete, radiation shielding and smart sensing cementitious materials, this study proposes a more efficient approach by covering the non-conductive glass fiber reinforced concrete (GRC) surface with a thin conductive layer. Single-walled carbon fiber (SWCNT) and carbon fiber (CF) were used as conductive additives in the mixture of electrically conductive surface coating. Dosages of 0.1%, 0.2%, and 0.3% (wt) for SWCNT and 0.2%, 0.4%, 0.6%, 0.8%, and 1% (Vol) for CF were preferred. According to these ratios, a total of 15 different conductive cement coatings were carried out. White Portland cement and fine silica sand were used as binder and filler material, respectively. The conductive cement-based coating with a thickness of approximately 3 mm shows good adhesion and integration properties, since it is placed in the mold gradually at the same time as the GRC, which acts as the substrate. Resistivity, impedance, heatability (electrothermal), TGA-DTA and microstructure characterization were performed to investigate the electrical, thermal and microstructural properties of the coatings.The impedance/resistance properties of the cement-based composite samples containing CF showed superior performance compared to the other samples. In TGA/DTA analyses, the amount of CF in the cement mixture did not affect the thermal weightlossmuch. The lowest resistivity values were measured as 20 and 80 Ω.cm for the CF1.0 and CF0.8 samples, respectively, and the electrothermal test results showed that the temperature reached 45.5 and 28 °C from 23 °C, respectively, by applying 24 V voltage within 1 h with a power consumption of 750 W/m2 and 232 W/m2.