Fatigue and Flexural Behavior of Reinforced-Concrete Beams Strengthened with Fiber-Reinforced Cementitious Matrix

The need for repair and rehabilitation is a crucial issue today in order to maintain a safe and efficient transportation network. One of the most recent innovative composite materials that has been proposed to the market is a fabric reinforced cementitious matrix (FRCM) strengthening system. This system consists of two components: a structural reinforcement mesh and a cementitious matrix. The structural reinforcement mesh consists of a polyparaphenylene benzobisoxazole (or PBO) fiber composite, while the cementitious matrix is a nontoxic grout system based on portland cement with a low dosage of dry polymers. The first aim of this study was to evaluate the fatigue resistance of reinforced concrete (RC) beams strengthened with FRCM under fatigue loading and postfatigue flexural strength to failure. The second aim was to investigate the durability performance of the FRCM after exposure to environmental conditioning including temperature, moisture, and sustained stress. All of the beam specimens examined in this study were subjected to fatigue loading for 2 million cycles before flexure testing. The stiffness reduction of both unstrengthened and strengthened RC beams was evaluated. The effects of environmental exposure were also examined. Results indicated that the FRCM strengthening system enhanced the fatigue and flexure performances of RC beams. Higher stiffness degradation was observed in beam specimens that were exposed to environmental conditioning. The exposed beam specimens exhibited improved performance under the postfatigue flexure test. (C) 2016 American Society of Civil Engineers.