Investigation of engineering properties of hot mix asphalt modified with solid product obtained from co–pyrolysis of different waste plastics

In this study; polypropylene (PP), high density polyethylene (HDPE), polyethylene terephthalate (PET) waste plastics were mixed in certain proportions, the prepared double and triple plastic mixture groups were co–pyrolyzed and pyrolysis product (solid, liquid and gas) yields were calculated. Modified bitumen was prepared by mixing pyrolysis solid products with pure 50/70 bitumen in 2, 4, 5, 6 % rates. In order to examine the effects of additives on pure bitumen; penetration, softening point, RV (rotational viscometer) tests were performed. With the addition of additives, it has been observed that the softening point increases and the penetration decreases. Compared to the pure bitumen; viscosity values at 60 and 75 °C increase in all modified bitumen, viscosity values decrease in HDPE–PET modified bitumen from 90 °C and in PP–HDPE–PET modified bitumen from 120 °C, respectively, viscosity values at 60 to 165 °C increase in PP–HDPE and PP–PET modified bitumen. In modified bitumen, it has been observed that viscosity change percentages according to pure bitumen are higher in low temperatures. With additive yields, modification, penetration, softening point and RV studies; PP–HDPE and PP–PET additives were selected and the optimum rates of these additives were found as 5 %. RTFOT (rolling thin film oven test), PAV (pressurized aging vessel), DSR (dynamic shear rheometer) and BBR (bending beam rheometer) tests were applied to pure and PP–HDPE and PP–PET modified bitumen. It has been seen with results that additives significantly increase DSR test parameter values such as wheel tracking (G*/sinδ), complex shear module (G*) and the high temperature PG of bitumen has increased by 1–2 step with the addition of additives. Also; it has been observed that the elasticity of the bitumen increases with the addition of additives. It has been observed that low temperature PG is the same in all bitumen. With SEM (scanning electron microscopy) and FTIR (Fourier transform infrared spectroscopy) analysis applied to pure and PP–HDPE and PP–PET modified bitumen, it was observed that the interactions of the additives with bitumen are more physical. It has been determined that density and void properties of modified and pure HMA are similar. In PP–HDPE and PP–PET HMA; it has been found by Marshall Design and wheel tracking tests that Marshall Stability increases by 8.45–12.87 % and 10.22–13.74 % respectively, and rutting performance by 32.81 % and 45.43 % respectively. Keywords: Plastic wastes, co–pyrolysis, modified bitumen, hot mix asphalt.