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

Abstract

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.