The Innovative Self-Sensing Strain Sensor for Asphalt Pavement Structure: Substitutability and Synergy Effects of Graphene Platelets With Carbon Nanotubes in Epoxy Composites

Abstract

Situ sensors with high accuracy, long durability, and high survival rate are crucial for the health monitoring of asphalt pavement. Due to the harsh environment during the construction period and service life, the monitoring components which can be buried synchronously with the construction period of the road surface become a difficult problem to be solved urgently. The development of functional composites sheds a new insight for pavement strain detection with remarkable self-sensing behavior. In this paper, the substitutability and synergy effect of graphene platelets with carbon nanotubes (CNTs), the effect of CNT types with different specific surface areas in epoxy composites to the morphological, electrical, and mechanical properties, and the strain-electrical resistance response peculiarity of composites were evaluated. The performance of developed composite sensors with epoxy encapsulation was investigated through laboratory experiments. The morphologies showed that CNT-GNP hybrids in composites present a better dispersion state because of the size effect and synergetic effect whereas the pure CNTs are prone to entangle with each other. Composites with CNT(SSA500) display the most amounts of conductive units in same dosage. CNTs and GNP can strengthen the elastic modulus of the epoxy matrix to basically the same as that of asphalt mixture within the range of 1100–1500 MPa. At last, Laboratory experiments have proved the promising prospect for CNTs-GNP/epoxy composites serving as the strain sensor. The developed composites-based strain sensor can provide a new prospect for asphalt pavement monitoring.