Experimental and numerical study on the penetration resistance of corundum-aggregate ultra-high performance concrete

The development of earth-penetrating weapons challenges conventional protective structures. To quantify the contribution of ultra-high-strength aggregates to the penetration resistance of ultra-high-performance concrete (UHPC), we launched 80-mm caliber scaled projectiles at velocities ranging from 300 to 500 m/s into corundum-aggregate UHPC (CA-UHPC) and reference UHPC targets. The depth of penetration (DOP) was recorded as a function of impact velocity. Experimental results demonstrate that corundum aggregate, through its ultra‑high hardness and strength, triggers projectile abrasion and fragmentation, thereby significantly enhancing the penetration resistance of the target. At impact velocities of approximately 300 m/s, 400 m/s, and 500 m/s, the DOP in plain UHPC exceeded that in CA-UHPC by 22.1%, 29.6%, and 60.7%, respectively; the advantage of high-strength corundum becomes more evident at higher impact velocities. Empirical models overestimate the DOP of CA-UHPC by 12.7–48.7%. Three-dimensional numerical simulations were conducted using ABAQUS/Explicit to replicate the penetration process. A parametric study was performed to investigate the effects of corundum volume fraction and the ratio of nominal aggregate size D to projectile diameter d ( D/d ). Numerical results indicate that the penetration resistance increases monotonically with volume fraction. The influence of the aggregate-to-projectile size ratio ( D/d ) depends on the volume fraction: at a low fraction (20%), the highest and most consistent resistance is achieved when D/d ≤ 1.0, whereas at a high fraction (50%), the size effect weakens and the optimum shifts to 1.0 ≤ D/d ≤ 1.5. The anti-penetration performance of CA-UHPC was quantified through large-caliber impact tests, and the accompanying simulations elucidated the roles of volume fraction and aggregate size, providing direct guidance for the design of ultra-high-strength shelter layers. • Large-caliber penetration tests were conducted on CA-UHPC targets. • Corundum aggregates reduce penetration depth by up to 60.7% versus plain UHPC. • A validated 3D model shows that DOP decreases with increasing corundum content. • Optimal aggregate size shifts with volume fraction: D/d ≤ 1.0 at 20%, 1.0–1.5 at 50%.