Response of UHPFRC and HDFRC under static and high-velocity projectile impact loads

This paper presents an experimental investigation of the mechanical properties of ultra-high-performance fiber-reinforced concrete (UHPFRC) and high-ductile fiber-reinforced composite (HDFRC) under a static load and of the impact resistance capacity of both materials under a high-velocity projectile impact load. Two types of materials, i.e., strength-oriented UHPFRC and ductility-oriented alkali-activated slag-based HDFRC, were designed and prepared. A series of experiments, including a compressive strength test, a uniaxial tension test, and high-velocity projectile impact test, were conducted to characterize the properties of the materials. From the test results, it was found that the UHPFRC mixture with a compressive strength of 155 MPa and a tensile strain capacity of 1.04% has toughness under a static tensile load similar to that of the HDFRC mixture with a compressive strength of 32.9 MPa and a tensile strain capacity of 7.9%. Although the UHPFRC mixture has a slightly higher resistance capacity to high-velocity projectile impact loads in terms of the failure mode, mass loss, crater area, and penetration depth compared to the HDFRC mixture, both materials showed higher impact resistance capacities than that predicted by the empirical model.