Heat Transfer Mechanism and Construction Temperature Control in Asphalt Paving

During asphalt paving, the temperature of asphalt concrete can exceed 120°C and reach up to 200°C, inducing significant thermal stresses in concrete box girders. Understanding these thermal effects, particularly under different paving procedures, is crucial but has received limited attention. In this study, transverse and vertical temperature gradients, along with associated stress fields, were investigated through field monitoring and 3D finite element analysis. Results show that the surface temperature of the top slab peaks about 45 min after paving, while the temperature gradients and resulting stresses decrease to their minimum values approximately 12 h later. The highest thermal stresses occur at the inner surface of the top slab and bottom surface of the cantilever slab. Compared with separate-lane paving, one-time paving generates more pronounced thermal effects. The time interval between successive paving operations strongly influences the peak stress at the inner surface of the top slab but has little effect on the cantilever slab. It is recommended that the interval between successive paving operations exceed 12 h; if shorter, reinforcing the inner surface of the top slab is advised to prevent thermal cracking. These findings provide guidance for optimizing paving strategies and improving bridge durability.