Optimizing the Mechanical Performance of Rubberized Concrete by Integrating Chip Rubber in Combination with Waste Tyre Steel Fibres

The incorporation of commercially available steel fibres in concrete notably improves the mechanical performance. Although steel fibres extracted from discarded tyres may differ from industrial steel fibres, they hold the potential to enhance concrete performance. Recognizing this improvement, there is an opportunity to recover the strength losses associated with rubberized concrete by integrating steel fibres derived from discarded tyres, as a sustainable practice. Despite numerous treatment methods developed to recover the strength of chip rubber concrete, none have yielded productive results due to the poor adhesion at the rubber/cement interphase. Moreover, substituting coarse aggregate with chip rubber incurs higher strength losses compared to replacing crumb rubber with sand in the concrete mix. As a result, efforts have been directed towards enhancing the performance of crumb rubber concrete. However, the incorporation of chip rubber notably improves the concrete’s energy absorption and toughness properties. Hence, identifying an effective method to recover the strength of chip rubber concrete is crucial for civil engineering applications requiring superior energy absorption and impact resistance. As a result, this research study focused on enhancing the mechanical properties of chip rubber concrete, reinforcing with waste tyre steel fibres extracted from discarded tyres, as a novel approach. Coarse aggregate was volumetrically replaced with chip rubber particles ranging from 5 to 20 mm up to 12.5% rubber replacement ratios. Waste tyre steel fibre content ranged from 0.25 to 1.00% of the total volume of concrete at each rubber replacement level. This study evaluated compressive and flexural strength separately for plain concrete, chip rubber concrete and rubberized concrete reinforced with waste tyre steel fibres. The results of the investigation demonstrated notable improvements in compression and flexural performance, particularly showcasing higher strength recovery capacities at lower rubber replacement levels.