Abstract
In the last few decades, premature deterioration of reinforced concrete (RC) structures has become a serious problem because of severe environmental actions, overloading, design faults, and materials deficiencies. Therefore, repair and strengthening of RC elements in existing structures are very important to extend their service life. There are numerous methods for retrofitting and strengthening of RC structural components such as; steel plate bonding, external pre-stressing, section enlargement, fiber-reinforced polymer (FRP) wrapping, and so on. Although these modifications can successfully improve the load-bearing capacity of the beams, they are still prone to corrosion damage resulting in failure of the strengthened elements. Therefore, many researchers used cementitious materials due to its low-cost, corrosion resistance, and resulted in the improvement of the tensile and fatigue behaviors. Different types of cementitious materials such as; fiber-reinforced concrete (FRC), high performance concrete (HPC), high strength concrete (HSC), ultra-high performance concrete (UHPC), steel fiber-reinforced high strength lightweight self-compacting concrete (SHLSCC), fabrics reinforced cementitious material (FRCM) and so on have been used to strengthen structural elements. This paper summarized previously published research papers concerning the structural behaviors of RC beams strengthened by different cementitious materials. Shear behaviors, flexural characteristics, torsional properties, deflection, cracking propagation, and twisting angle of the strengthened beams are explained in the present paper. Finally, proper methods are proposed for strengthening RC beams under various loading conditions.
Highlights
Reinforced concrete (RC) is a combination of concrete and steel reinforcement
It has been reported that the flexural load capacity of the strengthened beams with any type of fiber-reinforced cementitious materials has increased compared to the un-strengthened beams
For the beams retrofitted by epoxy resin, the failure mode was changed from flexure to brittle concrete cover separation without the failure of ultra-high performance fiber reinforced concrete (UHPFRC) laminates because laminates act as rigid plates and resulting in decreased deflection
Summary
Reinforced concrete (RC) is a combination of concrete and steel reinforcement. Unreinforced concrete has adequate compressive strength but low tensile strength, which results in concrete deterioration under lower traction or flexural applied loads. It is highly required to update and modernize structures for economic rising and prosperity For this purpose, improvement is needed in entire infrastructures, RC structures as they will be exposed to severe degradation due to the influence of freeze-thaw, aggressive environments, de-icing salts, and overloading. Improvement is needed in entire infrastructures, RC structures as they will be exposed to severe degradation due to the influence of freeze-thaw, aggressive environments, de-icing salts, and overloading It is a decisive issue for civil engineers to protect, retrofit, and maintain these deteriorating structural elements with the execution of new, low-cost repairing techniques to extend the lifetime of deteriorated and new structures [4,5,6,7,8]
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