High-velocity impact behaviour of a new hybrid fibre-reinforced cementitious composite

In this article, a new engineered cementitious composite reinforced with 0.6% volume steel fibres and 1.5% volume polyvinyl-alcohol fibres is developed aiming for enhanced impact resistance compared to other construction materials. Fundamental mechanical properties of the new composite including the compressive strength, Young’s modulus, tensile strength and flexural behaviour were tested. To calibrate the impact resistance of the new composite, high-velocity impact tests of panels made of the new material were conducted when subjected to impact from a standard 7.62 mm round in-service bullet fired from a knight armament SR-25 military rifle. For comparison, plain concrete panels and concrete panels reinforced with 2% volume steel fibres were also tested. The post-impact responses of the panels in terms of crater sizes, damage failure mode, fragmentation size, weight and regress velocity are analysed and compared to characterize the impact resistance of the new engineered cementitious composite. The test results demonstrate significantly enhanced impact and shatter resistance of the new hybrid fibre-reinforced cementitious composite with reduced spalling and fragmentation, localized damage areas and improved cracking resistance.