Effect of Fine Tyre Rubber Coating on Aggregate to Improve Bitumen-Aggregate Adhesion and Moisture Resistance in Asphalt Mixtures

Abstract

This study investigates the effectiveness of fine rubber powder sourced from waste tyres as a surface coating on aggregate to enhance bitumen–aggregate adhesion and improve the moisture resistance of asphalt mixtures. In response to the frequent early pavement distresses in Bangladesh caused by inadequate binder-aggregate bonding and water penetration, this study investigated a sustainable method utilizing recycled materials. A review of previous literature highlighted the potential of rubber-modified binders in increasing tensile strength and reducing stripping. To assess the performance enhancement, laboratory specimens were prepared with varying rubber contents (0%, 4%, 6%, 8%, and 10%) and tested using Marshall Immersion and Tensile Strength Ratio (TSR) tests. Physical and mechanical properties of both aggregates and bitumen were evaluated to ensure compliance with local standards. The results indicated that 8% rubber content yielded the highest retained stability (87.5%) and TSR value (91.00%), signifying optimal improvement in bonding and moisture resistance. Performance declined slightly beyond this threshold, likely due to excessive rubber disrupting mix uniformity. The findings confirm that fine rubber waste can be effectively utilized to develop durable, moisture-resistant, and sustainable pavement systems, particularly suitable for the climatic and infrastructural context of Bangladesh.