Self-Sensing Potential of Metashale Geopolymer Mortars with Carbon Fiber/Graphite Powder Admixtures

Multifunctional building materials with self-sensing capability have great potential for civil engineering applications. The self-sensing capability of typically calcium aluminosilicate matrices of cementitious or geopolymer materials is adopted by admixing electrically conductive admixtures in an amount that ensures optimal electrical properties and their proportionality to mechanical loading. The paper aims to evaluate the self-sensing capability of 4 metashale geopolymer mortars with graphite powder (GP) and carbon fibers (CF) in different ratios, including MGF 5/0, MGF 4.5/0.5, MGF 4/1, and MGF 3/0. The 4-probe measurements at 21 V DC input voltage on (100 × 100 × 100) mm3 samples with embedded copper-grid electrodes evaluate the gauge factor, which corresponds to the monitored changes in electrical resistivity. Despite the limitations of DC measurements, the self-sensing capability is observed for all the mixtures. The most promising response to dynamic loading with an FCR of 0.018%, is observed for the MGF 4.5/0.5 sample.