Reducing impact load on RC-Slabs using Expanded Polystyrene (EPS)

Reinforced Concrete (RC) slabs are widely used in structural applications due to their ability to withstand heavy loads. However, under impact loading conditions such as falling objects or debris, their brittle nature makes them prone to cracking and damage. To address this, Expanded Polystyrene (EPS) has been explored as an energy-absorbing material capable of reducing the severity of impact forces. Traditionally used as an insulating material, EPS possesses favorable mechanical properties-lightweight, high deformability, and cushioning capacity-that have led to its application in civil infrastructure as geofoam and lightweight fill. Despite its growing use, the potential of EPS as a protective surface layer for RC slabs under impact loading remains underexplored. This study investigates the effectiveness of a surface-mounted EPS layer in reducing the impact response of RC slabs. Six full-scale RC slab specimens were tested under vertical impact from a 90 kg steel ball dropped from a height of 1 m. Half of the specimens were cast as control slabs, while the other half included a 5 cm thick EPS layer atop the concrete. Accelerometers were used to capture dynamic responses, and a detailed finite element model was developed in ABAQUS, incorporating experimentally measured material properties and contact interaction at the EPS-concrete interface. The model accounted for separation and frictional behavior between the two materials. Experimental and numerical results showed that the EPS layer significantly reduced the maximum acceleration, displacement, and energy dissipation within the concrete slab compared to the control specimens. While control slabs absorbed more energy through cracking and damage, the EPS slabs exhibited reduced structural deterioration, indicating more efficient impact mitigation. These findings highlight the potential of EPS as a cost-effective solution to enhance the impact resistance of RC slabs. Future work will focus on parametric studies involving EPS thickness, EPS density, steel reinforcement ratio, intensity of impact load and concrete material properties to generalize the results for broader applications.