Development and evaluation of asphalt binders incorporating binary shape-stabilized composite phase change materials

Phase change materials (PCMs) have been recognized as promising materials for thermoregulation in asphalt pavements. To improve the thermoregulation range and efficiency, two polyethylene glycols with different molecular weights (PEG2000 and PEG10000) were absorbed into the treated diatomite powder via vacuum adsorption to prepare the binary shape-stabilized composite PCMs (the PCMs). The diatomite powder was modified through a combined process of calcination, microwave irradiation, and acid–base treatment. The thermoregulation performance and properties of asphalt binders incorporating the PCMs were evaluated through a series of laboratory tests. Results indicate that the combined treatment significantly increases the diatomite total pore volume from 0.475 cm³ /g to 0.766 cm³ /g and its specific surface area from 30.2350 m²/g to 71.1170 m²/g. The PCMs with the mass ratio mPEG2000:mPEG10000 = 4:6 enables precise regulation of the phase change temperature within the range of 48.40℃-64.85℃, with corresponding latent heat values ranging from 180.52 J/g to 199.88 J/g. At a PCMs content of 20 %, the temperature rise rate of the asphalt binder decreased by 41.3 % while that within the phase transition plateau was reduced by as much as 62 %, indicating a significant thermoregulation effect. The incorporation of the PCMs increases the softening point, viscosity, rutting factor, and creep stiffness of asphalt binders. Nevertheless, it compromises the low-temperature performance, as evidenced by decreased ductility and a lower penetration index. The appropriate content of the PCMs should be determined by balancing high- and low-temperature performance according to practical requirements.