Comparative SHPB dynamic response of rock-filled concrete and conventional vibrated concrete considering specimen preparation and aggregate morphology

Rock-filled concrete (RFC) is an innovative construction material that combines extremely large rock aggregates with high-performance self-compacting concrete (HSCC). This study experimentally compares the dynamic compressive responses of RFC and conventional vibrated concrete (CVC) using Split Hopkinson Pressure Bar tests. Specimens of different strength grades were tested at striker velocities of 11, 16, and 20 m/s, corresponding to strain rates of approximately 80–190 s −1 . Molded and split specimens were examined to assess preparation and end-surface effects, while selected angular and flaky aggregates were used to investigate morphological influence. Under the tested conditions, RFC exhibited higher peak dynamic stresses than CVC of comparable nominal strength, with increases of approximately 10–30% at lower strain rates and 20–60% at higher strain rates. RFC specimens containing angular aggregates also showed a 3–8% higher dynamic response than the corresponding specimens containing flaky aggregates. Both materials exhibited clear strain-rate sensitivity. The molded–split differences were associated with the combined effects of heterogeneous end-surface contact, wave impedance, end-face friction, and internal load transfer. Although the results indicate the potential of RFC for structures subjected to impact loading, the observed RFC–CVC differences reflect the combined influence of aggregate size, mixture characteristics, specimen preparation, and internal aggregate structure.