Effect of specimen size on dynamic compressive properties of fiber-reinforced reactive powder concrete at high strain rates

This study presents an experimental study of similar reactive powder concrete (RPC) cylinders with different sizes subjected to axial impact loading. Dynamic compressive experiments were conducted on two dimensional RPC specimens using split Hopkinson pressure bar device. 54 hybrid fiber-reinforced RPC samples with 2% steel fiber and 0.2% polypropylene (PP) fibers contents by volume were characterized at strain rates from 107 to 356 s⁻¹. Results from this and previous studies are analyzed to comprehensively investigate the effect of RPC specimen size on dynamic compressive performance. A series of quantitative analyses examining the relationship between dynamic properties and specimen size, strain rate, and steel fiber were conducted. Dynamic increase factor (DIF) of RPC compressive strength for specimens with larger diameters was consistently greater than RPC specimens with smaller diameters when the length to diameter ratio (l/d) was constant. RPC specimen size exhibited no visible effect on the critical strain DIF. Critical strain DIF increased with increasing strain rate and decreasing steel fiber addition. Critical damage variables of RPC specimens of greater size were higher than that of smaller sizes. Under identical strain rates, RPC specimen size had no visible effect on the DIF of Young's modulus or energy absorption.