Innovative technique of textile reinforced mortar (TRM) for flexural strengthening of reinforced concrete (RC) beams

Performance degradation of existing RC structures due to aging and environmental effects made strengthening of RC structures a global issue. Bond between the substrate member and new strengthening layer is considered a threshold for any successful strengthening technique. This study explores the efficiency of using cementitious high strength connectors in preventing the debonding of TRM strengthening layer from strengthened RC beams. The experimental program includes two parts. In first part, the effect of strength, ratio, diameter and distribution of connectors, for smooth and rough surfaces, on the tensile bond strength are examined. The applicability of these connectors is investigated in second part by means of RC beams strengthened with TRM comprising four and eight textile basalt fibre layers. The results demonstrate that the inclusion of cementitious connectors changed the failure mode from debonding failure to desired flexural failure. The proposed improvement exhibited increasing to cracking and ultimate load up to about 140% and 93%, respectively. However, a significant reduction in ductility of all strengthened beams was observed in comparing with the control specimen