Performance evaluation of waste polycarbonate as bitumen modifier

Abstract

Modification of bitumen has been used to improve the properties of bitumen and bituminous mixes to mitigate the problems of bitumen at extreme and quiescent conditions. It also provides better bitumen at extreme temperatures as well as saving construction cost. In this study, polycarbonate from disposed compact discs was used as modifier for bitumen with the aim of improving its consistency properties. To establish the presence of polycarbonate in the recycled compact discs, Fourier transform infrared (FTIR) spectra analysis was conducted on the waste compact discs. The FTIR results when compared with Infrared Spectroscopy Absorption Table (ISAT), revealed transmittance peaks described by the wave numbers 764-2967cm-1 (C-H), 1770cm-1 (C=O), 1599cm-1 (C=C), 1502cm-1 (C-C) and 1010-1020cm-1 (C-O-C). These peaks confirmed the compact discs as predominantly made up of polycarbonate. Comparative FTIR analysis carried out on the pure and modified bitumen revealed that there is appearance of additional new peaks with wave numbers 2371-2091cm-1 for C-H aromatic bending, 848-2110cm-1 for C=C aromatic bending and 1685-1700cm-1 for C-C aromatic stretching in the spectra of polycarbonate modified bitumen samples, indicating that the polycarbonate has undergone chemical interactions with the bitumen. Such interaction usually results in changes to the molecular structure of the bitumen. Also, comparative analysis carried out on some properties of pure and modified bitumen showed that the modifier decreases the penetration and ductility of bitumen but increases its specific gravity and softening point. These performance evaluation results indicate the ability of polycarbonate in improving the temperature susceptibility and rutting resistance of bitumen.