Highly resilient externally strengthened blasted concrete beams through improved self-centering

Structural protection is paramount due to the inherent brittleness of concrete structures and infrastructure, which represents a serious vulnerability and can undermine the safety of goods and result in casualties in the event of extreme events. Explosions and blasts generally result in uniformly distributed shocks to structural elements, causing serious damage and expulsion of concrete debris, ultimately rendering structures unsafe and unusable due to irreversible deformation and fragmentation. The use of mineral bonded composites with fibre and/or textile reinforcement as thin externally bonded strengthening layers has been identified as a promising strategy. In this paper, we report on the design of hybrid reinforced cement-based composites including polyethylene fibres and biaxial carbon grids with enhanced dissipation capacity against localized and distributed dynamic loading. In a pivotal structural application, as a result of a close collaboration between TU Dresden and Virginia Tech, we present the ability of these composites used as flexural reinforcement to provide 3 m concrete beams with self-centering attitude after blast loading, highlighting the synergistic effect of short and long fibres, which is crucial to mitigate spalling and maintain structural integrity even at high blast intensities, ultimately in-creasing robustness, resilience and safety.