Luffa sponge as a sustainable reinforcement for impact-resistant cementitious composites

Luffa sponge features a naturally optimized three-dimensional fibrous network, forming a lightweight and highly deformable bio-structure with high energy absorption capacity. Here we show that it can serve as a sustainable reinforcement to improve the impact resistance of cementitious composites. When embedded in cement paste, the luffa sponge forms a synergistic interface that enhances structural integrity and allows the composite to endure repeated impacts with minimal fragmentation. The composite maintains stable performance across a wide temperature range from –196 °C to 200 °C, showing low thermal sensitivity. Microscopic imaging and simulations reveal a gradual interfacial transition zone where hydrogen bonding leads to strength variation across the interface. This transition improves load transfer and contributes to overall durability. These findings highlight the potential of using bio-derived, architectured materials like luffa sponge to develop resilient and sustainable cement-based composites for structural applications.