Flat slab systems are widely utilized in construction due to their versatility and efficient use of space. Nevertheless, they are susceptible to flexural failure, particularly in the tension zone. To address this issue, slurry-infiltrated fiber concrete (SIFCON) has been proposed as a solution owing to its exceptional strength and durability. This research examines the effect of utilizing SIFCON in the tension zone of flat slab systems to enhance their flexural performance. The study encompasses testing eight identical slabs, two of which were cast with normal concrete, while the remaining six were hybrid slabs incorporating SIFCON. The specimens were subjected to vertical loading to compare their flexural behavior and identify the optimal dimensions for the SIFCON layer. The slabs had identical dimensions but varied in reinforcement. Group A had a reinforcement ratio of ρ = 0.5%, whereas Group B had a ratio of ρ = 0.335%. All slabs had a constant thickness of the SIFCON layer of 20 mm in the tension zone but varied in the dimensions of the SIFCON layer (100, 50, 30%) from the slab dimensions. A square plate with dimensions (140 × 140 × 20) mm supported the load for all slabs. The load was applied gradually until failure, and the load–deflection curves were recorded for each slab. The result showed that using SIFCON in the tension zone improved the flexural resistance of flat slab systems. The hybrid slabs with SIFCON demonstrated higher ultimate loads and lower deflections than the control slabs that used regular concrete. In particular, the hybrid slabs with a 100% SIFCON layer exhibited the best results, with a rise in ultimate load of 179 and 100% for Groups A and B, respectively, compared to the control slabs. In addition, there was a significant decrease in deflection of 62.35 and 52.38% for Groups A and B, respectively, relative to the control slabs. The study found that the optimal combination of the SIFCON dimension was when the 50% slab dimension was covered and the reinforcing bar area for the hybrid reinforcement system was smaller.
