Piezoresistivity in self-compacting concrete mixes with hybrid additions of carbon fibers and nanofibers

Abstract

Self-sensing properties of concrete structures can be achieved through the incorporation of additions in carbon-based materials (CBM) that modify electrical properties and provide piezoresistive (PZR) properties to the cement paste. PZR in pastes and mortar mixes with different types of carbon-based materials such as fibers of different sizes has been extensively tested. However, very limited studies on self-sensing properties in concrete are available due to the lower content of paste volume that leads to a decrease of concrete PZR. However, self-compacting concrete (SCC) can be an ideal candidate to implement PZR, due to two fundamental traits: the larger amount of paste of SCC compared to a conventional concrete and larger volumetric fraction of fiber can be incorporated due to a reduced effect on SCC workability and consistency. The present study aims to assess PZR properties of SCC with carbon-based components of different sizes. Combining carbon nanofibers (NFC) and carbon fibers (CF), in hybrid systems, could lead to obtain SCC with self-sensing properties identifying their effectiveness thresholds. The self-detection performance of PZR-SCC samples under mechanical stress was verified by resistivity and PZR experimental tests.