Mix design of UHPFRC and its response to projectile impact

• The mixture formulation and material properties of the UHPFRC are presented.
• Composites containing more than 2% of fibres by volume exhibit tensile hardening.
• Slabs made of this material are loaded by deformable and non-deformable projectiles.
• Fibre content beyond 2% by volume has no effect on reducing the crater diameter.
• Addition of fibres reduces penetration depth compared to reference concrete.

The aim of this paper is to describe mix design of Ultra High Performance Fiber Reinforced Concrete (UHPFRC) and its response to deformable and non-deformable projectile impact. UHPFRC represents a class of cementitious composite in which stress–strain response in tension undergoes strain hardening behaviour accompanied by multiple cracking, leading to a high strain prior to failure. The compressive strength of the resulting UHPFRC mixtures exceeded 130 MPa and direct tensile strength was in the range of 10 MPa. Several UHPFRC mixtures with different content of fibers were subjected to deformable projectile impact. It was found that specimens containing 2% of fibers by volume have optimal resistance against deformable projectile impact. Slabs containing 2% of fibers were further subjected to a non-deformable projectile impact. In addition, response of slabs made of traditional fiber reinforced concrete (FRC) is discussed. The magnitude of the damage was assessed based on the penetration depth, crater diameter and loss of mass.