The Temperature Measuring and Evaluating Methods Based on Infrared Thermal Image for Asphalt-Pavement Construction

To investigate the temperature segregation of asphalt mixture and the corresponding influence on construction quality, the infrared thermal imager was used to detect the loading, unloading, and paving temperature of the asphalt mixture, and a pavement-quality indicator (PQI) test was used to work out the density of pavement, and several conclusions were obtained. During the mixture delivery, the inner temperature changes little, whereas the surface temperature decreases greatly. The temperature decrease during the process from the unloading to the paving is mainly caused by the heat convection of the surface mixture. The paving mixture temperature is not consistent and obviously there is variation in features serrated. The maximum temperature of mat occurs toward the end of the paving period for a truckload of mixture, the lowest temperature appears after the beginning of the paving period of the next truckload of mixture, and the process repeats in this way. Transversal temperature segregation is more obvious than the longitudinal one. Compaction degree distribution along the transverse has the same variation tendency with temperature distribution. Finally, the evaluation criteria for asphalt-pavement temperature segregation were proposed based on the percentage of the point numbers with more than 6 degrees C variation of average temperature.