An investigation on the asphalt with enhanced damping properties: Development, performance evaluation and mechanisms

The present pavement noise-reduction approaches impair seriously the durability of pavement, therefore improving damping properties of pavement materials to attenuate noise is a developing trend. This study investigated an optimal component formulation designed to enhance damping properties of asphalt using recycled butyl rubber (RIIR) and styrene-butadiene-styrene (SBS) as modifiers. The pavement performance was examined to analyze the contributions of components in the asphalt through general properties, multiple stress creep and recovery (MSCR), bending beam rheometer (BBR) and segregation tests. Meanwhile, the microscopic morphology of asphalt was observed by Fluorescent Micrograph (FM) and Scanning Electron Microscope (SEM) in connection with the damping properties. The microscopic properties of asphalt were characterized using Gel Permeation Chromatograph (GPC), Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). The results indicate that the combination of RIIR, SBS and sulfur contributes to enhance damping properties and pavement performance of asphalt. FM images present the interlocking continuous phases with interspersed elastic molecules and SEM images exhibit the folded mesh structures, which is the ideal morphology for the asphalt with enhanced damping properties. The tests on molecular structures, functional groups and thermal properties demonstrate that the particular sulfurized crosslinking structures restrict flow deformation and provide elasticity in asphalt, thereby manifesting in the enhanced damping viscous response and damping elastic response macroscopically. Consequently, these findings highlight the potential of damping compound-modified asphalt, promoting the advancements in noise-reduction pavement materials.