Rice husk (RH), an abundant agricultural by-product, poses an environmental challenge if not properly managed. Through pyrolysis, this waste can be valorized into biochar (BC), a sustainable material with potential to modify asphalt binders. This study explored the use of RH-derived BC (RHB) as a modifier of an asphalt cement (AC) 60/70 asphalt binder to produce hot-mix asphalt (HMA) by the wet process and evaluate its mechanical performance. Initially, the physical and rheological properties of AC modified with 5%, 10%, 15%, and 20% RHB by weight were evaluated. Conventional tests were conducted, and the performance grade (PG) was determined at high and intermediate temperatures. Aging resistance was assessed, multiple stress creep recovery and linear amplitude sweep tests were performed, and scanning electron microscope visualizations were carried out. Based on the results obtained from this binder characterization phase, an asphalt binder modified with 10% RHB was chosen to produce the HMA. Marshall stability, indirect tensile strength (ITS), Cantabro, resilient modulus (RM), permanent deformation, and fatigue resistance tests were carried out on the control HMA (RHB/AC = 0%) and the modified HMA (HMA-RHB). The results show that RHB tends to increase the stiffness, aging resistance, and rutting resistance of the asphalt binder, while maintaining the PG at intermediate temperatures. As an AC modifier, it helped improve all the evaluated mechanical properties of HMA. Specifically, it increased strength under monotonic loading, ITS, and RM, and enhanced resistance to rutting, fatigue, and raveling, while moisture damage resistance showed a slight improvement but remained statistically unchanged.
Rondón-Quintana et al. (Sun,) studied this question.