Experimental investigation of corrosion-damaged RC beams strengthened in flexure with FRP grid-reinforced ECC matrix composites

摘要

In this study, composites fabricated using a fiber-reinforced polymer (FRP) grid-reinforced engineered cementitious composite (ECC) matrix were used for the flexural strengthening of corrosion-damaged reinforced concrete (RC) beams in combination with a patch repair technique. After the longitudinal reinforcements were corroded to the expected ratio by the electrochemically accelerated method, the corrosion-damaged concrete cover was removed, and then repaired with FRP grid-reinforced ECC matrix (FGREM) composites. The investigated test variables were mainly FRP grid types (carbon and basalt), strengthening amounts, corrosion level, and longitudinal reinforcement ratio. The experimental results indicated that the bearing capacities of the corroded beams were sufficiently improved using this strengthening technique. The intermediate debonding at the concrete substrate-to-ECC interface caused by flexural cracks could be completely suppressed. The use of a carbon fiber reinforced polymer (CFRP) grid with higher stiffness could produce a weaker ductile behavior and prematurely trigger critical diagonal crack-induced debonding. Furthermore, the flexural bearing capacities of the basalt-FGREM strengthened beams could be reasonably predicted according to the ACI-549.4R-13 provisions. However, the predicted results were relatively dangerous for carbon-FGREM strengthened beams, which failed under the control of the critical diagonal crack-induced debonding mode.