Effects of coconut shell charcoal powder combined with SBS on rheological properties of asphalt binder

Abstract

Conventional asphalt binders often suffer from inadequate stiffness, elasticity, and aging resistance under high temperatures and heavy traffic conditions. This study addresses these limitations by utilizing coconut shell charcoal powder (CSCP), a carbon-rich, porous biochar derived from agricultural waste, along with styrene-butadiene-styrene (SBS) polymer to enhance the rheological performance and sustainability of VG-30 asphalt binder. CSCP, incorporated at 2 %, 4 %, and 6 % by weight, provides high surface activity and thermal stability that improve binder stiffness and aging resistance, while 1 % SBS enhances elasticity and recovery through its elastomeric network. Rheological tests using the dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), and linear amplitude sweep (LAS) on unaged, rolling thin-film oven (RTFO)-aged, and pressure aging vessel (PAV)-aged samples, supported by field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR) analyses, revealed that the dual-modified binder (CSMB6S1) achieved an optimal balance of stiffness and elasticity, exhibiting superior rutting resistance, fatigue life, and high-temperature stability. The results highlight the synergistic reinforcement between CSCP and SBS and demonstrate the potential of coconut shell–derived carbon as a sustainable modifier for high-performance asphalt pavements. © 2025 Elsevier Ltd.