Piezoresistive properties of CNT reinforced cementitious composites

This paper characterised the piezoresistive properties of carbon nanotube (CNT) reinforced cementitious composites. Such factors as curing conditions, carboxyl functionalisation, water/cement ratio and oven drying were considered in the experiment and their effects on the piezoresistive sensitivity were experimentally investigated. Experimental results indicate that the electronic resistance of the CNT reinforced composites cured in a dry environment is negatively correlated with compressive loads. Furthermore, the functionalisation of CNT with carboxyl has beneficial effects on the piezoresistive response of the composites. However, neither moist cured composites nor the composites with a water/cement ratio of 0.5 show the piezoresistive behaviour, while the oven dried composites exhibit the highest piezoresistive sensitivity. This study indicates that the moisture content in the composite is the most important factor in developing the piezoresistive properties of CNT reinforced composites. With decreasing moisture content in the composites, the piezoresistive sensitivity is enhanced. It is expected that the piezoresistive properties of CNT reinforced composites can be efficiently used in developing a new type of sensor for the structural health monitoring of concrete structures.