Effects of preheating conditions on performance and workability of hot in-place recycled asphalt mixtures

Pavement preheating is of great significance for hot in-place recycling technology. In this study, different preheating temperatures (100 °C, 120 °C and 150 °C) and heating times (60 min, 120 min and 180 min) were set to simulate different preheating conditions for recycled asphalt pavement materials. Rutting tests, low-temperature bending beam tests, and freeze-thaw tests were conducted to investigate the effect of the different heating temperatures on the overall performance of recycled asphalt mixtures. Direct shear tests and gyratory compaction were used to evaluate the bond strength between the old and recycled pavement layers and the workability of the regenerated mixtures under the various heating conditions, respectively. The results showed that the performance and workability of a new pavement surface are both significantly affected by the preheating conditions and that the minimum preheating temperature of 120 °C can guarantee good performance and workability of recycled asphalt mixtures.