Asphalt concrete air void evaluation by applying infrared thermography

Abstract

ABSTRACT Asphalt concrete is an essential part of infrastructure, and its quality and structural condition directly impact traffic comfort and safety. Air voids is applied for assessing its structural condition. This research aims to establish a physical relation between the thermal behaviour and air voids of asphalt concrete using infrared thermography. To ensure accuracy, calibration techniques including geometric, radiation, and emissivity calibration were applied in the experiment. Four asphalt concrete specimens with different air voids were tested in this study. The results indicated a clear and constant relationship between temperature increase and air voids, which serve as a critical indicator for evaluating the structural condition of asphalt concrete. Additionally, the empirical experiment showed that the thermal behaviour in the first minute followed a different trajectory compared to the subsequent measurements. The numerical results and empirical formula derived from this research can serve as a basis for formulating the analytical equation that connects asphalt concrete air voids to observations from infrared thermography. Once this relationship is established, the structural condition of asphalt concrete can be evaluated using regular and commonly available infrared thermal cameras instead of relying on other specialised and single-use equipment.