Compression and tension stress-sensing of carbon nanotube-reinforced cement

This paper is aimed at characterising the self-sensing capability of carbon nanotube-reinforced cement, as enabled by piezoresistivity. Carbon nanotubes/cement composites with two different levels of carbon nanotube content (0.2% and 0.3% by weight of cement) are considered in the study and their pressure-sensitivity properties under both tension and compression are examined. The primary focus of the work is to explore the effects of two parameters including type of loading (tension or compression) and carbon nanotube concentration on the composite's piezoresistive behaviours. The experimental results show profound piezoresistive behaviours observed from composite with well-dispersed carbon nanotubes of only 0.3 wt%. It is also confirmed that tensile loading increases electrical resistance of the composite, while the opposite occurs upon compression. Furthermore, the composite's pressure sensitivity to changes in either the compressive or tensile stresses increases with the concentration of carbon nanotubes, as confirmed by the consistent changes in electrical resistance in response to both compressive and tensile stresses.