Understanding the role of waste cooking oil residue during the preparation of rubber asphalt

Abstract Bio oil was proved an effective modifier to improve the compatibility of rubber asphalt. However, the pathway in which the bio oil enhances the compatibility of rubber asphalt remains unclear. To understand the role of the bio oil in rubber asphalt during preparation process, the waste cooking oil residue (WCOR) was incorporated during the preparation of rubber asphalt in different scenarios. The compatibility of the prepared rubber asphalts was examined through the cigar tube test, the rheological characterization and the morphology observation. The compositional change of ground tire rubber (GTR) extracted from the prepared rubber asphalts was analyzed via the thermogravimetric analysis (TGA), and the chemical and fractional composition of the asphalt phase separated from the three rubber asphalts was analyzed via the Fourier transform infrared spectroscopy (FTIR) test and the thin-layer chromatography with flame ionization detection (TLC-FID) test. Results showed that the compatibility of the rubber asphalt with GTR swelled by WCOR prior to preparation was significantly improved compared with that of the rubber asphalt with untreated GTR and the rubber asphalt prepared by blending GTR and WCOR simultaneously. The results from chemical and compositional characterization suggested that the improved compatibility of the rubber asphalt incorporating GTR pre-swelled with WCOR was mainly attributed to the extended release of nature rubber (NR) and traces of synthetic rubber (SR) and inorganic filler into the asphalt phase.