Characterization of thermal properties of bituminous mastic containing different fillers to be used in the cool pavement.

• Optimized compositions of mastic were recommended in the cool pavement. • Heat flux was transferred in a different way in the cenospheres and the graphite. • Bruggeman's model can be used to describe the thermal properties of mastic. • Spherical cenospheres contributed less to rutting resistance of mastic. The cool pavement with the function of oriented heat conduction was designed to improve its deformation resistance and decrease the heat island effect. Lots of research had been performed on the thermal properties of asphalt mixture in the cool pavement, but less of them focused on the mastic which played a vital role in the heat conduction. In this study, the normal filler, the cenospheres and the graphite were adopted to prepare the mastic samples. The normal filler was made of the limestone, and the cenospheres were obtained during coal-burning process in coal-fired power plants. The thermal conductivity analyzer was used to investigate the thermal properties of mastic. The scanning electron microscopy was employed to observe the morphological characteristics of different fillers. Dynamic shear rheometer was adopted to evaluate the rheological properties of the mastic as a function of temperature. Bruggeman's model and the finite element method were used to analyze the mechanism of thermal transmission of mastic. Based on the results, the mastic with the ratio of binder:normal filler:cenospheres = 1:0.5:0.5 by weight was recommended to be applied on the top layer of the cool pavement to improve its thermal insulation, and the one with the ratio of binder:graphite = 1:1 was recommended in its sub-layer to improve its thermal transmission and rutting resistance. [ABSTRACT FROM AUTHOR]