Simulation Analysis and Optimization of Temperature Field for Hot In-Place Asphalt Pavement Recycling

The heating temperature field of asphalt pavement is a key factor affecting the quality of pavement heat-in-place recycling (HIR). Using the heat transfer characteristics of HIR, a three-dimensional heat transfer model was simplified into a one-dimensional heat transfer model along the depth direction. A temperature sensor was installed on the site to monitor the temperature change of the asphalt pavement at different depths under different heating powers, and the actual temperature and heat transfer model were highly compatible. Through this model, the influence of heater running speed and heater heat flux density on the temperature field of the asphalt pavement heated by infrared radiation (IR) was calculated by the finite differential method, and an optimal combination of heating is proposed. In accordance with construction continuity and minimum energy consumption principles, at the 3.0–3.5 m/min recommended running speed of the heating machine, the asphalt at a depth of 4 cm satisfied the temperature demand, but the asphalt on the road surface was prone to heat aging. The heating effect of the constant temperature variable power heating (CTVP) is ideal, but the continuous change in heating power increases the difficulty of construction. Constant temperature discrete power heating (CTDP) divides the ideal heat flux density curve into several stages according to the length of the heating plate in the heater, increasing the feasibility of constant temperature heating in engineering and reducing energy consumption.