Complex Impedance and Dielectric Dispersion in Carbon Fiber Reinforced Cement Matrices

Abstract

The electrical response of carbon fiber reinforced cement mortar over the frequency range 1 Hz–10MHz has been presented. The low frequency conductivity is shown to be directly influenced by increasing fiber dosage, with conductivity percolation occurring at dosages in the range 0.35%–1.0% (by volume). When viewed across the entire frequency spectrum, the conductivity and dielectric constant frequency dispersions reveal two regions of relaxation. The definition of these regions becomes more pronounced as the fiber dosage is increased. It is proposed that the low frequency relaxation process (1 Hz–1 kHz) is related to the enhanced charge transfer characteristics at the electrode–material interface produced by the presence of the carbon fibers in the vicinity of the electrodes. The high frequency relaxation process (5 kHz–10 MHz) results from a Maxwell–Wagner effect produced by the presence of highly conducting inclusions (the carbon fibers) in the low conductivity mortar matrix.

Development of conductive cementitious materials using recycled carbon fibres

“…The incorporation of the rCF modifies the diagram as shown inFigure 16. Both the reactance and electrical resistance values decrease and the feature attributed to the electrode polarization effects is not discernible, as described by previous researchers(54).Ford et al (53) demonstrated that the Nyquist diagram of cementitious samples is affected by the inclusion of conductive phases. The emerging high-frequency arc that appears on the left side of the diagram is related to the bulk features of the sample.…”

“…The Nyquist diagrams of cementitious materials with conductive inclusions normally exhibit three individual arc/features, accounting for the electrochemical reactions and product layer deposition at the electrodes and bulk-related features(53).Figure 15illustrates the Nyquist diagram for the neat UHPC concrete sample in which only two arcs can be observed. The spur element on the right side is related to the polarisation effects at the electrode(54). The rest of the diagram is part of the arc related to the bulk response of the sample.…”

Effect of fibre loading on the microstructural, electrical, and mechanical properties of carbon fibre incorporated smart cement-based composites

“…The mid arc is produced by a strong surface effect of double layer capacitance and surface resistance at the fibre-pore fluid interface (Schwarz, 1962;Schurr, 1964;Mason et al, 2002;Suryanto et al, 2016;Zhang et al, 2022). Most importantly, the bulk arc is the bulk response produced by the bulk conduction mechanism and the interfacial polarization (Christensen et al, 1994;McCarter et al, 2009). The bulk conductivity σ, as the parameter of interest in this study, situates at the transitional location where the double layer effect is diminished and the bulk response dominates (Zhang et al, 2022).…”

Characterization of Carbon Nanoparticles in Thin-Film Nanocomposites by Confocal Raman Microscopy

“…Carbon materials have been extensively investigated, especially graphene and carbon nanotubes, for a great variety of applications such as optical devices, electrodes, biosensors, as filler to reinforce materials, , or conductive composites. − Conductive coatings based on these carbon materials have also been further investigated. However, the conductive coatings are usually thick films composed of a polymer host with the conductive filler (graphene or carbon nanofibers) providing resistivities of 10 –1 –10 –3 Ω m. − Carbon black is a conductive filler with a wide particle size distribution (10 nm to 100 μm) , which is mainly used as rubber filler or reinforcement in paints, polymers, or gums .…”

“…Carbon materials have been extensively investigated, especially graphene and carbon nanotubes, for a great variety of applications such as optical devices, 1 electrodes, 2 biosensors, 3 as filler to reinforce materials, 4,5 or conductive composites. 6−8 Conductive coatings based on these carbon materials have also been further investigated.…”