Grid Types Used to Strengthen Reinforced Concrete Panels Subjected to Impact Loading

The protection of existing reinforced concrete structures against impact loads, the effects of blast, or both, has become a major concern of researchers and engineers. Sudden impacts and release of high-speed loads, such as those from bullets, fragment bombs, and bare explosive charges, can generate high pressures on structures, resulting in fragmentation that can cause serious damage, injuries, and casualties. Results from an experimental investigation performed on reinforced concrete slabs retrofitted with different grids and polypropylene, polyethylene, and steel meshes are presented. The testing program includes impact tests using a falling weight and fragmentation simulation using an air gun. These tests were conducted on square concrete panels with dimensions of 600 × 600 × 100 mm. Deflections and depths of penetration were measured, as were applied and absorbed kinetic energy and the kinetic energy of the resulting concrete fragments. Damage and mode of failure due to post-impact were also observed and recorded. Results and analysis of the data and observations showed that the concrete panels retrofitted with a combination of steel mesh and polyethylene grid provided the most promising retrofitting protection when compared with other options.