Influence of blast load on the bond characteristic of retrofitted RC slabs

Abstract

Although structures are commonly designed for standard loads, they can experience extreme loads, such as intentional or accidental explosions. Structural elements are not designed to withstand such loads and are often retrofitted to provide a higher level of protection. In this study, RC slabs were coated with glass fibre textile-reinforced epoxy resin for a higher level of blast protection. The bond characteristics of the applied retrofit and concrete substrate were experimentally and theoretically analysed. Fracture analysis was based on the total fracture area, providing a more accurate determination of the retrofit and composite system fracture energy. Based on the obtained results, a retrofit system consisting of two layers of chopped strand glass mats impregnated with epoxy resin proved to be most effective in mitigating the blast load and enhancing RC slab residual capacity. A pull-off test was used to determine the retrofit–concrete interface mode of failure. The results indicated the existence of a proper bond between the retrofit and concrete substrate, providing continuous stress distribution and enhanced load capacity.