Strengthening of Two-Way Slabs Using Fiber Reinforced Concrete, Near Surface Mounted and CFRP Layers under Impact Loading

This article investigates the effectiveness of five strengthening techniques for reinforced concrete (RC) two-way slabs subjected to impact loading. Fifteen square slabs were tested under drop-weight impacts to evaluate Fiber-Reinforced Concrete (FRC) with steel or polypropylene fibers, Externally Bonded Reinforcement (EBR) using Carbon Fiber Reinforced Polymer (CFRP), Near-Surface Mounted (NSM), and hybrid NSM-CFRP combinations. Results show improvements in impact resistance across all methods. FRC slabs with polypropylene fibers exhibited a 2.3 times increase in energy absorption compared to conventional RC slabs, while steel fibers reduced concrete scabbing by 35%. CFRP reinforced slabs (EBR) showed the highest strength, up to 34 impacts, almost triple the capacity of RC slabs. Hybrid techniques showed most effective, combining NSM and CFRP strips to reduce damage area by 28–59%. FRC offers a cost-effective solution for distributed reinforcement, EBR gives in localized protection, and hybrid methods result optimal performance for high-risk scenarios.