Investigation of activated carbon-modified bitumen using coconut charcoal

Abstract

This study investigates the use of activated carbon derived from coconut charcoal as a sustainable modifier to enhance the performance of bitumen for road construction in tropical regions. Conventional bitumen is prone to thermal softening and aging, reducing pavement durability under high temperatures. The research explores how mixing parameter variation influences the rheological, mechanical, and thermal properties of 60/70 penetration grade bitumen. A full factorial design was used to prepare 27 samples by varying activated carbon percentage (3%, 6%, 9%), mixing temperature (140°C, 150°C, 160°C), and mixing rate (2000 rpm, 3000 rpm, 4000 rpm). Standard tests such as penetration, softening point, ductility, and viscosity were conducted, followed by short term aging and microstructural analysis on the optimum sample. Results showed that activated carbon reduces penetration values and increases softening points, indicating improved hardness and heat resistance while maintaining the ductility within the required value range (100 cm+) for road constructions. The optimum condition was 3% activated carbon at 140°C and 3000 rpm. All modified samples met ductility requirements. The study confirms that coconut shell-derived activated carbon can enhance bitumen durability and thermal stability, offering a low-cost, eco-friendly solution for tropical pavement applications.