Self-sensing concrete made from recycled carbon fibres

The electrical and piezo-resistive responses of recycled carbon fibre (rCF)-reinforced concrete is analysed in this article. Two different PAN-based rCFs (monofilament rCF and fibrillated rCF sheets) incorporated into dry concrete mix were investigated. Piezo-resistivity was evaluated by simultaneously monitoring the variation in the applied DC voltage during both flexural and compressive tests. Although both plain and rCF-reinforced concrete samples showed piezo-resistive responses, the latter show increased signal-to-noise-ratio and thus behave like self-sensing materials. The electrical behaviour suggests a mixed control owing to both ionic and electronic conductivity, with the dominant one depending on the rCF content and rCF dispersion. This work enhances the possibility of generalising the use of smart cementitious materials in the civil engineering industry.