Target effects on Coral Aggregate Seawater Concrete penetration: 3D meso-scale study of aggregate-induced projectile deflection

The dynamic response of Coral Aggregate Seawater Concrete (CASC) to projectile penetration remains poorly understood. This study employs 3D mesoscopic simulations to decipher the individual and synergistic roles of aggregate strength, particle size, volume fraction, and mortar strength. Results demonstrate that enhanced aggregate strength significantly reduces penetration depth and increases deflection angles. Mortar strength exhibits a non-monotonic influence on deflection, initially increasing and subsequently decreasing the angle. A critical aggregate-to-projectile size ratio of 3 is identified, corresponding to the maximum penetration depth. Furthermore, an increase in aggregate volume fraction paradoxically increases penetration depth while reducing deflection, with the highest fraction (40 %) facilitating direct penetration. Crucially, the aggregate type is paramount: weaker coral aggregates permit straightforward penetration, whereas stronger ones induce significant trajectory deviation. These findings provide valuable insights into optimizing CASC for improved penetration resistance, with implications for enhancing the protective capabilities of coastal and island infrastructure against high-velocity impacts.