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To decrease the solar radiation heat entering the pavement, glass microsphere (GM) was selected as filler to replace limestone mineral filler (LMF) to improve the thermal resistance of asphalt mixture. The influence of GM on the thermal performance of asphalt pavement was studied by testing the thermal conductivity of asphalt mixture. It is found that the thermal conductivity could be reduced by 23.4%, which was beneficial to improve the cooling effect of asphalt pavement. A series of test, including dynamic repeated creep test, three-point bending test, dynamic modulus test and semi-circular bending test, were used to evaluate the influence of GM on the deformation resistance, low-temperature cracking resistance, dynamic performance and fatigue life of asphalt mixture. The results show that replacing LMF with GM negatively affected the above road performances of asphalt mixture. In further studies the actual rutting resistance of asphalt pavement with GM should be investigated by considering the cooled pavement structure and the elastic/creep performances of asphalt mixture.

In this paper, glass microsphere (GM) was used to prepare thermal resistance asphalt mixture (TRAM) by replacing limestone mineral filler (LMF). The mixture was applied in the top layer of asphalt pavement to decrease the solar radiation transferring into asphalt pavement. The thermal, elastic and creep parameters of TRAM were obtained using a series of laboratory tests. Based on the above parameters, the heat transfer and rutting models of thermal resistance asphalt pavement (TRAP) were established. The results show that completely replacing LMF with GM in asphalt mixture resulted in thermal conductivity decreasing by 23.8% and specific heat capacity increasing by 10.6%. Compared with control asphalt pavement, the heat absorption of the designed pavement at the depth of 4 cm decreased by a maximum of 5.5% and the maximum temperature reduced up to 1.7 °C (at 12:00 p.m.). The cooling effect of thermal resistance pavement was verified by an indoor irradiation test. The rutting depth of the middle and bottom layers in the TRAP reduced by a maximum of 8.5% after 500 thousand times of standard axis load were applied. Due to the excellent thermal resistance effect, GM can be used to reduce the internal temperature of asphalt pavement and improve the rutting resistance of asphalt pavement.

In order to cool asphalt pavement by replacing limestone mineral filler (LMF) with hollow glass microsphere (HGM) in asphalt mixture, this work preliminarily evaluated the thermal, high-temperature rheological and fatigue properties of asphalt mastic. The microstructure, particle size distribution, chemical element composition and crystal structure of LMF and HGM were tested to characterize their physical and chemical properties. A series of tests, including scanning electron microscope, Fourier transform infrared, thermal conductivity, spectral reflectance, multiple stress creep recovery (MSCR) and linear amplitude sweep (LAS) tests were performed to investigate the influence of HGM on the performances of asphalt mastic. The results show that HGM/LMF and asphalt were physically blended, and some HGM particles were broken when preparing asphalt mastic. Completely replacing LMF with HGM in asphalt mastic resulted in a decrease of thermal conductivity by 40% and an increase of infrared reflectance by 60%. The MSCR test result shows that HGM negatively affected the anti-rutting performance of asphalt mastic, while the LAS test result shows that HGM could extend the fatigue life of asphalt mastic. The findings in this study indicate that HGM is a potential material for cooling asphalt pavement.