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Title: Using Steel Fibres to Increase the Projectile Impact Resistance of Cementitious Composites

Author(s): Radoslav Sovják, Sebastjan Kravanja, and Jan Zatloukal

Publication: Symposium Paper

Volume: 347


Appears on pages(s): 39-58

Keywords: cementitious composites, crater area, crater volume, depth of penetration, projectile impact, shear crack analysis, steel fibres

DOI: 10.14359/51732657

Date: 3/1/2021


Steel fibres in cementitious composites play a crucial role in making structures less susceptible to the damage caused by projectile impacts. A synergistic effect is achieved when steel fibres and an otherwise brittle cementitious matrix are blended together to produce a high-performance fibre-reinforced cementitious composite with enhanced ductility and strength. These composites also display strain hardening in tension, which leads to enhanced energy absorption and dissipation capacity. In this study, in-service 7.62 × 39 mm [0.28 × 1.54 in.] cartridges were used as projectiles. The muzzle velocity and weight of the projectiles were 710 m/s [2329 ft/s] and 8.04 grams [0.284 oz], respectively. Projectiles were shot with a stationary semi-automatic rifle into specimens made of high-performance fibre-reinforced cementitious composites with various fibre volume contents. Fibres used in this study were straight with a smooth surface. The aspect ratio of the fibre was 108:1 and corresponding dimensions were 14×0.13 mm [0.55×0.005 in.]. The tensile strength of the fibres was 2,800 MPa [406 ksi] and the modulus of elasticity was 210 GPa [30,458 ksi]. Owing to their exceptional mechanical properties, the fibres played a key role in controlling the response of the specimens when impacted by projectiles. The highest fibre volume content used in this study was 2% by volume; the cube compressive strength of the resulting mixture was 144 MPa [20.9 ksi]. Specimens were examined for the possible presence of spalling, scabbing, cracking, or full perforation. Depth of penetration, crater area, and crater volume were also tested. Results showed that steel fibres, due to the aforementioned synergistic effect with a cementitious matrix, notably protected specimens from erosion and significantly reduced cratering damage.