Analysis of different types of cementitious-based composites used as shear strengthening system for reinforced concrete beams

Abstract

The global tendency to apply sustainable criteria in most of the productive fields and the limited durability and the pathologies that reinforced concrete elements suffer are aspects that explain the increasing necessity of strengthening this type of structures. The evolution of strengthening techniques has consisted in the development of new technologies that ease the application of the solution and minimise the time structures are out of service. In this way, using composite materials in construction has represented a revolution in the strengthening of structures. The textile-reinforced mortar (TRM) is a composite material that combines textiles, made of high strength tensile fibres, with cementitious matrix. A remarkable feature of this solution is that it does not require organic resins for its manufacturing and application, unlike the techniques as fibrereinforced polymer (FRP). The present work has consisted in the analysis of the mechanical and structural behaviour of reinforced concrete beams strengthened against shear stresses using different types of TRM. To fulfil this aim, an experimental campaign has been carried out. Nine reinforced concrete beams have been subjected to experimental tests, eight of them shear strengthened with four different combinations of textiles and mortars. Using the experimental data, an analytical study has compared the ultimate capacity of the reinforcements with the predictions obtained from three analytical models included in design standards of FRP and TRM. The results show that the strengthening system is able to increase an average of 33.7% the shear capacity of reinforced concrete beams. On the other hand, the results of analytical studies indicate that models adapted from FRP standards might show a better prediction capacity than the obtained with the code specifically developed for TRM reinforcements, which has performed significantly conservative.