Behaviour of reinforced crumbed rubber concrete (CRC) beams under static and repeated loading

Crumbed Rubber Concrete (CRC) is made by partially or fully replacing fine aggregate from the conventional concrete mix with similar size crumb rubber particles, usually from scrap tyres, making it a sustainable alternative to normal concrete. Most of the previous studies on CRC investigated the influence of rubber particles on various aspects of the concrete by comparing the behaviours of different concrete mixes having same mix proportions except the proportion of crumb rubber. As a result, these studies compared the behaviours of concretes having different compressive strengths. This study aims to understand the behaviours of different CRC mixes of similar compressive strength and how they differ from the conventional concrete of same strength. To achieve this several CRC mixes having the similar compressive strength, and different mix proportions were developed, and specimens made from these mixes were used to compare their behaviour experimentally at a material level as well as at member level under various structural loads. In this study, flexural and shear behaviour of reinforced CRC beams were investigated under static load condition. Beams were also tested under repeated loading to evaluate their energy absorption capacity. These experimental results were used to compare the behaviour of similar strength CRC with different amount of rubber particles. Results were also compared with the predictions of design guidelines for conventional concrete to identify the difference between CRC and idealised conventional concrete of same compressive strength, and the applicability and accuracy of these guidelines on predicting the behaviour of CRC. Finally, the applicability of the existing constitutive models for conventional concrete for numerically simulating the behaviours of CRC structural members was examined. For this purpose, two constitutive models for concrete, available in commercial finite element software, were used to simulate the behaviours of the reinforced CRC beams and benchmarked against the experimental measurements. The study concluded that the similar strength CRC behaves similarly in material and structural level while having slightly reduced shear capacity. The energy absorption capacity of beams was not affected by rubber content. The available design standards and constitutive material models can be used in CRC with minor modifications to shear capacity and shear factor coefficient