Electrical characteristics and conductivity mechanism of self-sensing asphalt concrete

The existing conductive asphalt concrete is not suitable for self-sensing of asphalt concrete structural damage. In order to realize the perception of electrical signals on the structural damage of asphalt pavement, A self-sensing asphalt concrete is designed, and the relationship between condition change and resistance change of asphalt pavement is established by adding multi-conductive phase materials to ordinary asphalt concrete. The influence of different amounts of conductive additives on the volumetric parameters, electrical properties, and mechanical properties of asphalt concrete has been studied, the influence of volume parameter changes on the electrical properties and variability of conductive asphalt concrete was clarified, and the correlation analysis between volume of air voids (VV) and resistivity has been established. Nano-CT scanning, the distribution of conductive phase materials in asphalt concrete was characterized, and its long-short synergistic conduction mechanism was revealed, which provided a theoretical basis for the application of self-sensing asphalt concrete. Results indicate that the failure spacing of conductive particles of single-doped graphite is 2 µm, and the volume content of graphite should not be less than 0.68% to have weak conductivity. Considering the volume parameters, electrical properties and mechanical properties of asphalt concrete, the composite modification method of graphite and steel fiber is proposed, the recommended graphite content of conductive phase material is 0.68%, and the content of steel fiber is 0.9–1.1%. The internal structure failure of asphalt concrete is mainly manifested in the change of volume of air voids (VV), the electrical properties of conductive asphalt concrete show a negative correlation with the VV of concrete, and the change of resistivity of asphalt concrete can be used to predict the damage state inside the pavement structure.