Incorporating hollow glass microsphere to cool asphalt pavement: Preliminary evaluation of asphalt mastic

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. (C) 2020 Published by Elsevier Ltd.