Evaluation of the properties of bio-asphalt derived from waste cooking oil and low-density polyethylene through the pyrolysis process

The aim of this study is to prepare a bio-asphalt for flexible pavement construction using a fixed-bed pyrolysis reactor. This method involves incorporating waste cooking oil (WCO) and low-density polyethylene (LDPE) as feedstock materials. Through this study, an attempt has been made to make use of waste materials and promote the use of environmentally friendly binders in sustainable road construction. The pyrolysis experiment was conducted at different temperatures, varying from 250 °C to 500 °C for different blends of waste cooking oil (WCO) and low-density polyethylene (LDPE), i.e., 1:0, 3:1, 1:1, 1:3, and 0:1, respectively. At a temperature of 350 °C, the pyrolysis process is more effective for converting various blends of waste cooking oil (WCO) and low-density polyethylene (LDPE) into bio-asphalt. The maximum bio-asphalt yield of 82 wt% was reported for the 1:3 blend at a temperature of 350 °C. The elemental analysis of an equal mass of waste cooking oil (WCO) and low-density polyethylene (LDPE) reported a carbon content of 83.93 wt%, a hydrogen content of 13.29 wt%, and a lower oxygen content of 2.55 wt%. The Gas Chromatography Mass Spectrography (GC-MS) analysis indicated the presence of chemical compounds such as pentadecane, heptadecane, dodecane, cyclopentylpropyl, and hexacosene in the 1:1 blend. The thermogravimetric and derivative thermogravimetric analyses indicate that the 1:1 blend and 1:3 blend can withstand temperatures around 473 °C and 475 °C, respectively. The Fourier transform infrared spectroscopy (FT-IR) analysis showed the presence of alkane, alkene, ester, and other aromatic compounds. Based on this present study, it has been noted that the chemical composition of a 1:1 blend of waste cooking oil (WCO) and low-density polyethylene (LDPE)-based bio-asphalt contains similar chemical compositions as asphalt binder, and it can be used as a modifier for conventional asphalt binder.