Experimental and theoretical study on the flexural behavior of RC beams strengthened with cementitious grout

In this study, we experimentally and theoretically studied the flexural behavior of RC beams that were strengthened with cementitious grout based on the static loading test of beam specimens with two reinforcement positions and three thicknesses of reinforcement layers. We compared and assessed the failure modes, moment-deflection relationship, strain distribution along the height of the cross-section, strain of tensile longitudinal reinforcement, and the cracking behavior of the RC beams. The results showed that the RC beams strengthened with cementitious grout exhibited similar or greater flexural capacity compared to conventional RC beams, as well as a significantly greater ultimate deflection. Therefore, we concluded that the cementitious grout can be used to repair and reinforce existing RC beams with degraded performance, and can effectively restore or improve the bearing capacity of RC beams. Moreover, the reinforcement position and thickness significantly impacted the reinforcement effect of the RC beams. The results of the crack development analysis showed significant differences in the moment-crack width relationship between the RC beams strengthened with cementitious grout and the control beams. Thereafter, we proposed a rational calculation method to predict the flexural bearing capacity and deflection of RC beams strengthened with cementitious grout by considering the reinforcement positions and thicknesses of reinforcement layers. Additionally, the calculated results using the proposed method and the experimental results were found to be in good agreement, which indicates that the proposed method is accurate and can be used in engineering applications.