Abstract:
Ethiopia’s highway network showed that a high percentage of roads are suffering from fatigue,
creep, and rutting in the long term. These stresses may have occurred due to the shortage in the
mechanistic properties of either of the increase in traffic load; these modifying properties of
asphalt enhanced the mechanistic properties of hot mix asphalt. Nowadays, the use of recycled
waste materials in road pavement is regarded not only as a positive option in terms of
sustainability but also as an appealing option in terms of providing improved service performance.
Therefore, the main aim of this research is to investigate the effects of crumb rubber and
polyethylene terephthalate plastic polymer in asphalt mixture modification on the pavement
responses using a finite element approach. The modification was performed both for asphalt
binder and for asphalt mixture. The laboratory tests for asphalt mixture, such as a standard
Marshall and Indirect tensile strength were conducted. In total, 69 samples were prepared: 15 as
a control mix, which was prepared by blending course and fine selected with asphalt binder of 4,
4.5, 5, 5.5, and 6% of their weight to determine the optimum binder content, and the remaining to
investigate the effects of adding different crumb rubber and polyethylene terephthalate plastic
percentage to asphalt mix. Two proportions of crumb rubber (10% and 15%) by weight of asphalt
binder were tested to modified asphalt binder, and four proportions of polyethylene terephthalate
plastic (0, 2, 4, and 6%) by weight of crushed stone filler were used as partial replacement of filler
content in the asphalt mix. The dimensional finite element model of Hot Mix Asphalt pavement
structure was developed using Abaqus software to quantify the stress and deformation developed
in the asphalt mixture due to static load. The asphalt binder test results showed that adding 10%
crumb rubber as a modified reduced penetration by 1.56% and increased the softening point (by
4.33%) of the modified asphalt binder. The addition of 10% crumb rubber as asphalt binder
modified and 2% of PET as partial replacement of crushed stone in the asphalt mixture was
considered the best modifier that achieved maximum stability (increased by 0.17%), minimum flow
(decrease by 20.07%), maximum stiffness (increased by 20.71%) and higher tensile strength of the
asphalt mixtures. When crumb rubber and PET polymer are combined, vertical deformation is
reduced by 23.65% and the percentage of stress is increased by 7.36%.
