Numerical Simulation Study on the Temperature Rise Characteristics of Asphalt Pavement During Hot In-Place Recycling

The heating efficiency of hot in-place recycling for asphalt pavements directly depends on parameters such as hot air temperature, hot air velocity, and heating machinery travel speed. However, the interactions among these parameters and their influence mechanism on deep-layer temperature remain unclear. In this study, a three-dimensional transient heat transfer model of an asphalt pavement was established to simulate the effects of different parameters under intermittent heating conditions, including hot air temperature, hot air velocity, and travel speed, on the pavement surface temperature and temperature at a depth of 4 cm. The results indicate that travel speed exhibits the most sensitive effect on temperature, with an absolute regression coefficient of 8.5 °C·min/m. A reduction of 0.5 m/min in travel speed increases the deep-layer temperature by approximately 4.25 °C. Every 50 °C increase in hot air temperature raises the deep-layer temperature by about 5.75 °C. The effect of hot air velocity on temperature is relatively small within the range of 12 to 14 m/s. The heat penetration efficiency increases monotonically as the hot air temperature and velocity increase or the travel speed decreases. This study reveals the quantitative relationship between heating parameters and temperature responses, providing a theoretical basis for parameter optimization in hot in-place recycling processes.