Influence of protective layers on the resistance of concrete structures under blast and impact loading

The rising threat of blast and impact events to critical infrastructure has underscored the need for advanced protective solutions to enhance the durability of structural materials.Protective layers can decrease the damage and increase the resistance of structures against such short-term dynamic loading.Different approaches are presented: dispersed fibre reinforcement and endless-fibre textile reinforcement.High-performance concrete with dispersed fibre reinforcement (HPFRC) is recognised for its exceptional strength and resistance to dynamic loading.However, its performance under blast conditions can be further improved with the addition of protective layers.This study investigates how different protective layers and their position affect the damage and structural behaviour of HPFRC subjected to blast loading.One of the protective layers is pliable and made of polyurethane, the other is stiff and made of glass/epoxy.Experiments were conducted using an explosive, placed in direct contact with the panels, to assess damage under different protective configurations.These configurations included uncoated panels, panels with one-sided stiff coatings, two-sided pliable coatings, and panels with stiff layer on one side and pliable layer on the other.On the other hand, textile-reinforced concrete (TRC) with endless carbon fibre reinforcement is used to strengthen existing structures.On the rear side of an impact-subjected structure, the textile-reinforced strengthening layer enables a membrane action and self-centering effect, reduces scabbing, and increases the perforation limit.On the impact-facing side, strengthening layers consisting of a cover layer and a damping layer decrease the impact energy induced into the concrete structure.The findings of all approaches shown in the work demonstrate the potential benefits of adding protective layers, particularly in reducing the scabbing, while also indicating that certain configurations can reduce the likelihood of full perforation.The results also reveal potential disadvantages of applying protective layers, such as increased cracking and reduced residual capacity of concrete structures.