Experimental investigation of energy consumption performance in enhanced foam-concrete sandwich slabs

This study focuses on rockfall impact damage to roof slabs and tunnel shed slabs and adopts the design principles of bulletproof composite armor to develop energy dissipation buffer structures. Two types of structures were proposed: foam-sandwich reinforced concrete slabs and concrete slabs reinforced with carbon fiber cloth and aramid fiber cloth on their back surfaces. Drop hammer impact tests were conducted to evaluate the impact resistance of the slabs. A total of 24 specimens were fabricated, considering factors such as foam slab thickness and the concrete material used in the top slab. The experimental results demonstrated that the rigid outer layer effectively dissipated impact energy into the internal flexible buffer layer, thereby maximizing the energy absorption and cushioning performance of the rigid–flexible composite structure. The energy consumption ratio of all slabs exceeded 97%, highlighting the sandwich structure’s capability to significantly extend the impact duration of the drop hammer on the reinforced concrete slabs while reducing the average impact force. Furthermore, ceramic tiles on the surface of the foam slab effectively mitigated the direct impact of the drop hammer, enhancing the overall impact resistance of the structure. Fiber reinforcements, particularly carbon fiber cloth, effectively restrained concrete fragments from dispersing, thus improving safety and structural integrity. • Enhanced Impact Resistance with Foam-Sandwich Design : Incorporating a foam-sandwich layer into reinforced concrete slabs significantly improves their ability to withstand impacts, reducing peak support reaction forces by 34.2% and peak accelerations by 30.9% compared to ordinary concrete slabs. • Effective Energy Dissipation through EPS Integration : Utilizing Expanded Polystyrene (EPS) foam particles in the top slab material enhances energy absorption capabilities, leveraging the material's closed-cell structure to dissipate impact energy more efficiently. • Surface Reinforcement with Ceramic Tiles: Applying high-hardness ceramic tiles to the surface of sandwich concrete slabs further strengthens impact resistance, successfully withstanding maximum impact energies in testing scenarios. • Localized Damage Mitigation with Carbon Fiber Reinforcement: Employing carbon fiber cloth as a backing material effectively confines damage to localized areas and prevents concrete debris dispersion during impact events, outperforming aramid fiber cloth in this regard. • High Energy Dissipation Efficiency Across Designs: All tested concrete slab configurations demonstrated the ability to dissipate over 97% of total input energy during impact, with efficiency increasing alongside higher impact energies.