Abstract
This paper presents the results of the evaluation of rubberized bitumen using crumb rubber as the influence material. Conventional bitumen is the material used in asphalt pavement construction. However, due to its challenges such as initial high cost of construction, rutting, cracking and failure in road construction within shorter time frames of about 0–15 years, an alternative material which is the rubberized bitumen has been recommended as a possible replacement. Rubberized bitumen is an innovative concept which involves the incorporation of crumb rubber derived from discarded tyres into bitumen binders, creating a modified binder with unique properties that contribute to improved pavement characteristics. This research was aimed at partially replacing conventional bitumen – a material often used in the construction of asphalt pavement with rubberized bitumen at varied proportions to evaluate its mechanical properties, in order to ascertain whether or not it is suitable for asphalt pavement construction. Eight (8) numbers of rubberized asphalt samples were prepared using The Marshall Mix Design Method. Varied proportions of rubberized bitumen at 0%, 3%, 6% and 9% were used to evaluate the various mechanical properties such as percentage voids, density, Marshall-stability, flow, and the stiffness of the rubberized asphalt. The results illustrate the relationship between the introduction of modified bitumen and the resistance of the asphalt mix to deformation. Initially, at 0% modification, the stiffness of the asphalt mix was measured at 3.52 KN/mm. As the percentage of modified bitumen was increased to 3%, the stiffness of the asphalt mix improved to 4.47 KN/mm, indicating enhanced resistance to deformation. However, with further increases in the percentage of modified bitumen to 6% and 9%, the stiffness decreased to 3.74 KN/mm and 2.76 KN/mm, respectively. Also, a higher value of stiffness typically suggests a greater resistance to deformation and, consequently, better performance of the asphalt mix. Therefore, the results demonstrate that the introduction of modified bitumen at a 3% concentration significantly improved the stiffness and resistance to deformation of the asphalt mix. However, excessive modification beyond this concentration led to a drop, as evidenced by the decrease in stiffness observed at 6% and 9% modification levels. This suggests an optimal range for the percentage of modified bitumen to achieve the desired stiffness and performance characteristics of the asphalt mix.