Effect of Reactive Powder Concrete (RPC) and Textile-Reinforced Mortar (TRM) on the Punching Shear Behavior of Flat Slabs with Post-Openings

The presence of openings in RC flat slabs, particularly post-openings, significantly affects the punched shear capacity of the slab. This study examines the influence of square and circular post-openings on flat slabs. Furthermore, this study aimed to assess the effectiveness of two distinct strengthening techniques, reactive powder concrete (RPC) and textile-reinforced mortar (TRM), on slabs. The objective was to examine the impact of each approach on the slabs and compare their performance. The experimental study involved the preparation and casting of seven specimens. The results showed that the slab with square and circular post-openings (STC, CTC) exhibits a significant decrease in both the first cracking load and the ultimate load capacity in comparison to the slab without openings (C). The specimens strengthened with RPC or TRM had a higher first cracking load compared to the reference specimens (STC and CTC). The ultimate load capacity of slabs with square or circular post-openings strengthened with RPC or TRM increased by 16% to 30%. The existence of post-openings within the slab reduces its ductility index and energy absorption capacity. The application of strengthening techniques (RPC, TRM) on slabs with post-openings resulted in a notable increase in the ductility index, ranging from 2.5% to 12.3%. Additionally, it significantly increased the ability to absorb energy, with an enhancement in capacity ranging from 20 to 42%. Generally, the negative effects of post-openings on flat slabs can be mitigated by applying strengthening techniques (RPC, TRM). Specifically, RPC has shown a significant influence on the performance of the slab.