Analysis of the shear behavior of reinforced recycled aggregate concrete beams based on shear transfer mechanisms

• Published in: Engineering structures 2023-10, Vol.293, p.116616, Article 116616
• Main Authors: Trindade, Juliana C., Garcia, Sergio L.G., Lacerda, Thaís N., Resende, Thomás L.
• Format: Article
• Language: English
• Subjects: Concrete beams; Recycled aggregate concrete; Shear strength; Shear transfer mechanisms
• ISSN: 0141-0296; 1873-7323
• DOI: 10.1016/j.engstruct.2023.116616

•An experimental-theoretical investigation of the shear transfer mechanisms of reinforced recycled aggregate concrete beams with and without stirrups is presented.•A detailed analysis of the shape and kinematics of the critical crack and the aggregate interlock surfaces obtained from direct shear tests is performed.•Theoretical analyses showed the reason and the way the coarse aggregate type influences (or not) the shear strength of the beams. This study aims to contribute to a more rational understanding of the shear behavior of reinforced recycled (concrete) aggregate concrete beams. Twelve reinforced concrete beams - six with natural aggregate concrete (NAC) and six with 100% coarse recycled concrete aggregates (RAC) - with same concrete compressive strength (38 MPa) and proportions of cement and aggregates per volume, varying the longitudinal (1.15%, 1.75%, and 2.50%) and transverse (0%, 0.086%, and 0.114%) reinforcement ratios, were tested under a 4-point bending setup with a full-field displacement monitoring. A thorough examination of the failure span along the tests, associating critical crack shape and kinematics with an investigation of the shear transfer mechanisms provided by mechanical models from the literature was conducted. Direct shear tests on push-off specimens followed by analyses of their failure surface evaluated the characteristics of shear crack surfaces and a proper modeling of the aggregate interlock contribution. The results showed a 28% average reduction in the shear strength of RAC beams with no stirrups in comparison with their reference beams (NAC), whereas beams with stirrups of same characteristics showed a similar shear strength, regardless of the type of coarse aggregate. The evaluation of the shear transfer mechanisms enabled an understanding of the reasons for those behaviors. Experimental results were also compared with those predicted in design codes. They were conservative for beams with stirrups, and, in general, less accurate than those obtained by the shear transfer mechanisms.