Effect of Aqua-Thermally Treated Rubber Aggregate and Waste Tyre Steel Fibre on the Mechanical Properties of Rubberized Concrete

Abstract

The depletion of finite mineral aggregate and the detrimental impacts stemming from the accumulation of numerous waste materials emphasize the urgent need for manufacturing alternative recycled aggregate. The partial replacement of natural aggregate in concrete with these materials promotes the sustainability of construction materials. As a result, rubber aggregate derived from discarded tyres has emerged as a viable option for fine aggregate substitution, particularly at lower replacement levels. Generally, rubber inclusion diminishes the strength of the Rubberized Concrete (RuC). However, it transforms the concrete’s brittleness into a ductile behaviour. Identifying the poor bond strength at the rubber/cement interphase as the main reason for strength losses, several physical and chemical treatment methods have been suggested to enhance the performance of RuC. Water-based and thermal treatment have emerged as cost-effective and straightforward approaches among the various treatment methods. However, recent investigations into RuC underscore that recovering entire strength losses is not achievable solely by employing treated rubber particles. On the other hand, integrating steel fibres derived from waste tyres into concrete has been currently distinguished as a promising way to augment mechanical properties. Considering the interaction between these matters, water-base and thermal treatment were combined to produce Aqua-Thermally Treated Rubber Aggregate (ATT-RA) to produce RuC reinforced with Waste Tire Steel Fibers (WTSF) as a novel approach. The experimental results revealed that the combination of ATT-RA and WTSF notably improved the performance of RuC, achieving 100% compressive and flexural strength recovery up to 5% rubber replacement levels compared to plain concrete due to the stiff surface texture of ATT-RA and the crack bridging effect of WTSF. Besides, design strength was recovered up to 10% rubber content, highlighting the potential of utilizing RuC reinforced with WTSF in structural applications.