Hybrid mineral-bonded protective layers for enhanced self-centering capacity of reinforced concrete beams subjected to blast

With the aging of infrastructure and the threat of terrorist attacks and military actions worldwide, there is a need to develop retrofits for critical infrastructure, which is often made of reinforced concrete. While it is paramount that these retrofits enhance robustness of structural members so that structural elements remain operable, it is also desired that they show minimal signs of significant plastic deformation (self-centering) and reduce spalling and fragmentation. Mineral-bonded composites with textile and/or short, dispersed fiber reinforcement are one such solution to provide existing structural elements with additional resistance and resilience. To determine the improvements provided by the devised retrofitting strategies, four reinforced concrete beams were constructed and tested in a shock tube research facility under a series of progressively higher blast loads. The results of these tests show that retrofits featuring either textile reinforcement or hybrid reinforcement (i.e., a combination of textile and short dispersed fibers) have a strong self-centering capability, even in situations where reinforced concrete beams would fail. In addition, single-degree of freedom analytical simulations are performed to highlight the predictive capabilities of the method and the accuracy of the calculated sectional capacity of the beams.