The development and advancement of cement-based composites has shown promise in recent years. It is important to examine new materials and technologies so that they can satisfy the ever-changing repair and strengthening application needs in the structural engineering field. This paper presents an experimental study on the behavior of reinforced concrete beams strengthened in shear using an externally applied fiber-reinforced cementitious matrix (FRCM). The first aim of this study is to investigate the effectiveness and the performance of the polyparaphenylene benzobisoxazole fiber-reinforced cementitious mortar (PBO-FRCM) system for shear strengthening. The second aim is to study the shear performance of the PBO-FRCM system in terms of the availability and absence of internal transverse shear reinforcements. A comparison study with previous experimental work and the relevant code is done to evaluate the shear performance of the PBO-FRCM system. The test results include the observed shear contribution of the PBO-FRCM system, the failure mode of the strengthened beams, and the influence of the internal transverse shear reinforcements on the shear performance of the PBO-FRCM system.

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.

Composite materials are widely used in retrofitting bridge and building construction in order to improve the load-carrying capacity of understrength or deficient structural members. This paper presents experimental research conducted on full-scale one-way RC slabs strengthened using three different composites. The flexure performance of a new innovative composite, fiber-reinforced cementitious matrix (FRCM), is evaluated and compared with that of conventional fiber-reinforced polymers for some specimens under laboratory condition and for other specimens exposed to environmental conditioning before testing. The test results illustrate the impact of the composite materials on enhancing the flexural strength of RC slabs and their durability performance.

Concrete structures retrofitted with fiber reinforced cementitious matrix (FRCM) have become widespread due to their mechanical and durability performances. However, the behavior of FRCM -strengthened RC members under service loads is still a concern, and more efforts need to be done. In this study, a nonlinear three-dimensional finite element (FE) model has been developed to study the performance of reinforced concrete (RC) beams strengthened by (FRCM). The model was validated against the experimental results gathered from six beams tested under three-bending points. Consequently, the primary numerically studied parameters were longitudinal steel reinforcement ratio and concrete compressive strength. A cohesive damage parameters were investigated to represent the experimental results. Also, the theoretical flexural capacity of strengthened beams based on ACI-549 code was evaluated based on the numerical method results. As a conclusion, the numerical results are in a very good agreement with the experimental ones regarding yielding load, ultimate load, and failure mode. In addition, the developed models from parametric studies concluded the insignificant effect of concrete compressive strength on increasing the ultimate capacity of strengthened beam. However, the steel reinforcement ratio has a major impact on enhancing the ultimate capacity of strengthened beams.

The development of cement-based composites has been fruitful in the recent years. It is important to examine the new materials and technologies so they can fulfill repairing and strengthening applications in the structural engineering fields. An experimental study on the behavior of reinforced concrete beams strengthened in shear using an externally applied fiber reinforced cementitious matrix (FRCM) is presented. The PBO-FRCM system consists of two components: the reinforcing mesh is Polyparaphenylene benzobisoxazole – PBO fiber composite and the bonding agent is cementitious matrix. The test variables included two different configurations of U-wrapped systems and the PBO reinforcement’s ratio. The aims of this study were to investigate the effectiveness and the shear performance of the PBO-FRCM system for strengthening reinforced concrete beams in shear. All the beams were instrumented and tested under four-points loading. The test results included the observed shear contribution of the PBO-FRCM system and the failure mode of the strengthened beams.