A review of punching behavior of slab–column connections with recycled coarse aggregate concrete

This paper presents a state-of-art regarding the punching of flat slabs made with coarse recycled concrete aggregate concrete (CRCAC). Punching shear is a phenomenon that occurs in reinforced concrete slabs when concentrated loads are applied near a column or other support. It refers to the failure mechanism where the concrete reaches shear failure at a critical section around the column. CRCAC is a structural material that conforms with circular economy concepts, but its design for punching using current formulae may be unsafe due to the lower strength of the concrete that can be caused by the shape or the surface cleanness of the recycled aggregates when compared with the natural ones. The results highlight the need for further research on this area, since the available experimental results are few and mainly from tests with thin slab specimens. Since the punching phenomenon is dependent on the scale effect, it is mandatory to have more results for slabs with representative thickness. The applicability of the models for punching resistance in EC2, ACI318-19, and the upcoming second generation of EC2 was also investigated. These codes can produce safe estimates for CRCAC slabs. However, it was found that the second generation of EC2 is less conservative than the other models.