Impacts of the Co-Pyrolytic Product From Waste Cooking Oil (WCO) and Polypropylene (PP) on Physical and Rheological Properties of Bitumen

Abstract

This paper aims to investigate the effects of the co-pyrolytic product produced from the co-pyrolysis of waste cooking oil (WCO) and polypropylene (PP) on pure bitumen by using some physical and rheological tests. To reach this goal, the product was obtained by producing from the co-pyrolysis of WCO and PP at distinct conditions. Different pyrolytic products with different structural properties can be obtained from the co-pyrolysis of various materials at different pyrolysis conditions. It was not found any study in which bitumen was modified with the co-pyrolytic product produced from the co-pyrolysis of WCO and PP materials at specified blending ratios and conditions, as described in this paper. For this reason, this paper investigates the effects of this co-pyrolytic product as an additive on bitumen in order to improve some of the rheological and physical properties of bitumen and to overcome some problems for the first time. The mixture ratio was determined as 1:2 (WCO:PP). PG 64-22 neat bitumen was modified with this co-pyrolytic product, and some features of the bituminous binders were detected by using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), penetration, softening point, dynamic shear rheometer (DSR), rotational viscometer (RV), a rolling thin film oven test (RTFOT), a pressurized aging vessel (PAV), a bending beam rheometer (BBR), storage stability, and scanning electron microscopy (SEM) tests. From the FTIR results of the modified binders, it was found that the intensity of the peak around 2357.69 cm−1 increased with the addition of this pyrolytic product. This pyrolytic additive hardened the pure bitumen’s consistency, increased its viscosity, improved its resistance against rutting deformations, and enhanced its high-temperature performance. It can be said that PG 64-22 pure bitumen can easily be modified with this pyrolytic product at the conditions described in this study. Additionally, this co-pyrolytic product improved the high-temperature performance grade (PG) of pure bitumen from PG 64 to PG 76 when it was used at 5% of the weight of neat bitumen. The findings demonstrated that the modified bituminous binders containing 3% and 5% co-pyrolytic product had suitable storage stabilities. © 2026 by the author.