Cast Method Effect of Carbon Nanofiber Aggregates on Structural Health Monitoring

Previous research on carbon nanofiber aggregates (CNFAs) have shown stable and reliable results for stress sensing with alternating current. The CNFAs necessarily contain carbon nanofibers (CNFs), responsible for the conductivity of this sensor. In addition to the other ingredients present in a CNFA, two 23 gauge welded galvanized steel wire meshes are embedded inside the CNFA cube to create a bridge between the external electrical impedance measuring device and the electrical impedance produced in the CNFA cube. Traditionally, CNFs were mixed in the cement mortar during CNFA casting. However, in this research, CNFAs are cast with CNFs glued to the wire meshes using conductive adhesive to improve the sensitivity of the cement-based sensor. CNFAs were tested under progressive monotonic uniaxial compression for the sweep-frequency test at the frequency range of 500 Hz to 300 kHz. A comparative study on the results from the two sets of CNFA tests shows that sensitivity can be improved when CNFS are glued on wire meshes with conductive adhesive. This paper includes the study of CNFA casting with new technique that increases the accuracy and reliability of sensors in structural health monitoring.