Surface functionalization of rubber particles to reduce phase separation in rubberized asphalt for sustainable construction

Application of crumb rubber in asphalt has demonstrated many performance advantages for the pavement industry while bringing a solution for the disposal of the scrap tire. However, the introduction of rubber to asphalt binder has challenges associated with rubber segregation and workability. To address the latter issues, continuous agitation and high mixing temperature is commonly used which increases energy consumption, disintegration of crumb rubber, and emission of greenhouse gases. This paper introduces a newly developed surface activated rubber (SAR) prepared via a hybrid method of microwave treatment and bio-modification to alleviate the associated problems. The properties and performance of SAR were compared with those of conventional crumb rubber modified (CRM) and microwave-activated crumb rubber modified (M-CRM) asphalt. Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and computational analysis using density functional theory (DFT) indicated successful grafting of biomolecules on the rubber particles. SAR showed 86% reduction in segregation index compared to the other CRM scenarios. Such enhancement was also reflected in a significant improvement in workability of SAR modified binder compared to the other CRM scenarios. Mechanical tests showed high fracture energy (167 J/m2) for SAR modified asphalt, which was approximately three times higher than that of conventional CRM asphalt (57 J/m2).