TRC and hybrid solutions for repairing and/or strengthening reinforced concrete beams

Over the last 20 years, composite materials, especially carbon epoxy, have been developed for the repair and strengthening of reinforced concrete structures. This expansion is mainly due to their very good mechanical performances as well as their easy, fast and unobtrusive application. However, composites also have a number of limitations that make the alternatives advantageous. For example, their poor compatibility with sustainable development (use of polymer resins and large amounts of carbon) can inhibit their development, or at least slow it down. Other limitations include their low efficiency ratio (low failure strain or stress) and relatively low fire behaviour. This article highlights the good performances of TRC (Textile Reinforced Concrete) hybrid solutions in the repair of reinforced concrete beams, in terms of both ultimate and service behaviour (before the longitudinal steel yielding). TRC hybrid solutions exhibit very similar performances to those of traditional solutions such as CFRP in the case of service limit state, but less desirable in the case of the ultimate limit state. The use of TRC alone to strengthen a reinforced concrete beam seems less advantageous, and while it significantly improves the ultimate performance, it cannot be considered in the context of increasing the bearing capacity. Finally, this article shows that the cracking kinematics of the repaired and/or reinforced beams is very similar to that of an undamaged reinforced concrete beam, and the composite reinforcement does not affect the qualitative evolution of the crack opening. A model based on the Eurocode 2 approach has been proposed, which is encouraging but requires further testing. (C) 2012 Elsevier Ltd. All rights reserved.