Sustainability Impact of Coconut Shell as Coarse Aggregate Replacement in Hot Mix Asphalt

Most previous researchers have undertaken studies aimed at improving the sustainability and environmental impact of road pavement, particularly hot mix asphalt, also known as asphaltic concrete, by substituting natural aggregates with waste products. This investigation comprehensively examined the aggregate properties, bitumen properties, and Marshall test properties. In line with sustainability goals, bitumen grades 80/100 PEN and ACW14 were utilized. To assess the sustainability benefits of using coconut shells (CS) in the wearing course design, bitumen compositions ranging from 4.5%, 5.0%, and 5.5%, as well as various mix designs with varying per-centages of coconut shell, were employed. The investigation generated parameter determination data for CS 3%, CS 6%, and CS 9%, allowing for a comparison of their mechanical and physical properties, with an emphasis on sustainability and environmental factors. In this context, it's worth noting that CS demonstrated significant sustainability advantages, with an Aggregate Crushing Value (ACV) of 0.69%, far lower than the 19.10% observed for traditional aggregate. Furthermore, CS exhibited higher water absorption at 35.36%. Notably, CS 3% in 4.5% bitumen content emerged as the most sustainable partial replacement option, boasting a stiffness value of 4461.44 N/mm, indicative of superior strength and performance. Consequently, this study successfully achieved the goal of identifying the characteristic ACW14, incorporating coconut shell as a sustainable and environmentally friendly alternative in hot mix asphalt, aligning with sustain-ability objectives in the field of road construction and pavement materials.