EFFECTS OF WASTE PLASTIC AS PARTIAL REPLACEMENT OF BITUMEN AND USE OF COFFEE HUSK ASH AS MINERAL FILLER FOR THE PERFORMANCE OF HOT MIX ASPHALT

Abstract

Bitumen properties and external factors such as climate and traffic volume conditions govern hot mix asphalt pavement performance. Bitumen is viscous-elastic naturally and very sensitive to temperature, which influences its rheological properties. Flexible pavements are linked to extreme high-temperature causing rutting and fatigue cracking. Pavement distress shortens service life and increases maintenance costs. This research focused on improving pavement resistance to distresses by modifying the rheological properties of bitumen and using alternative fillers such as coffee husk ash (CHA). In this study, two phases were utilized. The first phase was collecting samples, and the second contained three sub-phases. To design a material quality test, the first step was to develop a Marshal mix design and three types of mixtures which was a mixture of normal HMA with SD filler, with CHA filler, and a combination of CHA filler and 3, 6, 9, and 12% PET plastic. Rolling thin film oven test (RTFO) and Dynamic shear rheometer are used to analyze the rheological properties of asphalt binder (DSR). Finally, for evaluation purposes, results of 3D-Move analysis software for moving vehicles under various loads and speeds were obtained. AST result shows that at 6% PET containing bitumen has better LVER when compared with original bitumen that changes from 2.49, 23.0, and 64.7% to 7.5, 50.2, and 87.1% at a temperature of 21.1, 37.8, and 54.40C, respectively. On the other hand, PG determination of the original binder has no variation at 3% PET but improved from PG 58 to PG 64 and PG 70 when the bitumen is modified at 6 and 9% PET plastic. From MSCR criteria, test result at 9% PET modified binder can be used for heavy traffic and approaches to very heavy traffic compare with 0, 3, and 6% PET plastic and a significant improvement for rutting resistance at a test temperature of 700C. The penetration and ductility value decrease with softening point increase as the PET content increases from the conventional test result. Furthermore, from the marshal test, CHA filler is a better performance of HMA mixture compared with SD filler. At 6.8% optimum PET plastic higher stability (15.9KN) and density value (2.268g/cm3 ) and lower flow (2.96mm), VMA (14.83%), and VFA value (73.01%) as compared with unmodified bitumen of 14.30KN, 3.5mm, 2.256g/cm3 , 15.62%, and 75.06% value respectively at 4% air void provided. The analysis 3D-Move software showed that asphalt binders with higher PET plastic content have the best performance as the stiffness of the asphalt mixes would increase with the addition of PET plastic. Therefore, the evaluation showed that partial replacement of PET plastic with the range of 6 to 9% improves the rheological properties by stiff the binder and rutting resisting performance of binders at high-temperature range and increasing the LVER has a better performance of HMA mixture