Impact of angular and fiber crumb-rubber on fresh, mechanical, and durability properties of eco-friendly concrete

Crumb-rubber is a sustainable solution for the development of environment friendly durable concrete. However, the behaviour of crumb rubber-reinforced concrete is primarily dependent upon the size and shape of the rubber. In this study, two types of crumb-rubber that is, angular crumb-rubber (ACR) and fibre crumb-rubber (FCR) was partially replaced with coarse aggregate to investigate the behaviour of crumb rubber-reinforced concrete. The fresh and hardened mechanical properties of the mixes were investigated, where crumb-rubber was replaced with coarse aggregates at 0, 2, 4, 6 and 8% and cement was replaced with fly ash (FA) of Class F at a constant ratio of 15% in the mix. It was found that the incorporation of ACR and FCR in concrete mixes caused reduction in the workability by approximately 43 and 21%, respectively. Also, the average compressive strength decreased by approximately 34 and 42% at 28-days with the addition of ACR and FCR in the mix. In addition, the splitting-tensile and flexural strengths reduced by approximately 28 and 11%, respectively with the addition of ACR in the concrete. However, the addition of FCR in the mix resulted in the increase in splitting-tensile and flexural strengths by approximately 8.1 and 27.7%. The prediction equations developed in this study accurately predicted the splitting-tensile and flexural strengths of both ACR and FCR-based concrete mixes with an average predction accuracy of about 90%. Overall, in comparison to ACR, the addition of FCR resulted in a significant improvement in the concrete failure mechanism, which resulted in increased tensile and flexural strengths promoting FCR concrete a promising material for the construction industry.