Blast resistance of hybrid fibre reinforced concrete containing polyvinyl alcohol, polypropylene and steel fibres with various shape parameters

This paper experimentally investigates the blast resistance of hybrid-fibre high performance concrete reinforced with various combinations of polyvinyl alcohol (PVA), polypropylene (PP) and steel fibres. The binary reinforcement systems were designed using combinations of steel/PP and steel/PVA fibres with various fibre geometries. Eleven different batches were examined to determine the influence of the parameters of the hybrid reinforcement (the material, shape parameters of the fibre, combinations of fibres) on the blast resistance of the concrete. Mechanical parameters under quasistatic load (flexural strength, compressive strength) were determined and load-displacement curves were captured. Real blast tests were performed on slab specimens (500 × 500 × 40 mm) according to the modified methodology M-T0-VTU0 10/09. The damage to the slab, the change in the ultrasound wave velocity propagation in the slab specimens before and after blast loading in certain measurement points, the weight of fragments and their damage potential were evaluated and compared. The results indicate that hybrid fibre reinforcement, when properly designed, can significantly enhance the overall blast resistance of concrete and can reduce spalling. Steel/PVA combinations provided higher blast resistance compared to steel-PP fibre mixes. The specimen containing a combination of 50 mm steel fibres and 12 mm PVA fibres showed the best performance under blast load.