Strengthening and repair of deficient reinforced concrete columns using textile-reinforced mortar: State-of-the-art review

The use of Textile-reinforced mortar (TRM) in the retrofitting of concrete structures has been studied extensively over the last two decades as they have gained considerable popularity as an alternative to Fiber-Reinforced Polymer (FRP). A growing body of literature recognises the significance of employing TRM to repair concrete columns. This is imperative, considering that the deterioration of the load-bearing capacity in concrete columns poses substantial risks to public safety. Therefore, to optimise and update TRM repair practices, a systematic review is necessary to comprehensively analyse the beneficial contributions and identify the associated challenges. This paper presents a state-of-the-art review of existing research on repairing concrete columns using TRM in relation to five categories of failure modes observed in typical existing structures. The key parameters and the results of studies focusing on columns made of inadequate concrete compressive strength, corrosion of reinforcement, buckling of bars, splitting bond failure, exposure to elevated temperatures and eccentric loading are critically evaluated through logical comparison and analysis. Notably, TRM demonstrates its efficacy in increasing the load-bearing capacity of concrete columns with inadequate strengths and eccentrically loaded columns by factors of 1.33 and 1.18, respectively. Additionally, TRM confinement significantly improves the cyclic deformation capacity by delaying bar buckling in poorly detailed old-type RC columns. However, it is noteworthy that the yield and peak loads of TRM strengthened columns decrease with an increase in the initial corrosion ratio of internal reinforcement. The evidence leads to the conclusion that TRM is a promising solution for repairing concrete columns needing improvement, emphasising a non-proportional increase in strength gain with the addition of TRM layers. The paper concludes by identifying existing knowledge gaps and proposing directions for future research in structural strengthening for concrete columns.