Effects of specimen characteristics, fibre and mix constituents on the acoustic performance of rubberised concrete for traffic noise walls

Recycling end-of-life tires (EOLT) presents a sustainable solution for addressing a major waste issue in many countries. This study focuses on the reuse of EOLT as construction materials, particularly in the form of EOLT-based rubberised concrete. However, several research gaps hinder the understanding of this construction material for implementation into practice. This study delves into key parameters, including admixture composition, aging, thickness, rubber distribution, and surface roughness, which play pivotal roles in designing and implementing rubberised concrete noise barriers. The paper presents the results of investigations into the performance of fibre-reinforced rubberised concrete when entrained with air, shedding light on flexural toughness and post-crack behaviour. The effects of incorporating fly ash and ground granulated blast furnace slag (GGBFS) as cement replacements are also examined. The acoustic performance of fibre-reinforced rubber concrete is studied, including the impact of sample conditioning (surface saturated dry or dry). The results indicate that air-entraining admixtures, the replacement of coarse sand with tire-derived rubber shreds, and the inclusion of recycled polypropylene fibre significantly enhance the mechanical and acoustic properties of the concrete. For instance, compressive strength improves by 43%, flexural strength by 120% and acoustic performance nearly twice, while water absorption and volume of permeable voids remain relatively unaffected. This study suggests an optimized sustainable mix design with rubber replacing more than 75% of the aggregate volume. It underscores the potential of EOLT-based rubberised concrete as an environmentally responsible construction material, offering enhanced performance across multiple domains, including noise attenuation barriers.