Effect of Reinforcement Parameters on the Impact Resistance of Cementitious Composites for Vehicle Restraint Systems

The presented study investigates the dynamic resistance of cement-based large-format elements with various types of reinforcement and retrofitting. Both inner and outer reinforcement has been assessed. The effect of matrix type (low, high, and ultra-high-strength), amount of steel fibres, and ribbed reinforcing steel on impact toughness has been evaluated. The influence of an additional polymer-based layer to increase impact resistance level has also been investigated. The effectiveness of each reinforcing method has been compared. An large-scale impact hammer device KYV-I-2020 (up to 1100 J) has been used to determine the impact toughness. The results show that ribbed reinforcing steel increases the impact toughness more effectively than the fibre reinforcement, steel mesh and additional polymer layer. However, fibers significantly reduce fragmentation, especially at a higher concentration of 2.5 vol%, contributing to the overall higher impact resistance of the elements and their safety in practical use. The test results also show a significant effect of the matrix type, with the most increased impact toughness achieved when using a high strength matrix. The addition of an antifragmentation polymer layer then provides a further increase in impact toughness. The results also indicate that similar resistance capacity can be achieved using different reinforcement combinations, which is crucial for designing the material composition with the optimal performance/cost ratio. The presented research is a part of the development process of the restraint systems for stopping trucks. The data obtained has been used to create the elements with suitable composition; their effectiveness has been successfully verified by numerical simulations and real tests.