Strengthening and retrofitting of reinforced concrete columns using ultra-high performance fiber reinforced concrete jacketing-A comprehensive review

This paper evaluates the behaviour and load-carrying capacity of confined reinforced concrete (RC) columns, focusing on their strengthening and retrofitting using ultra-high performance fiber reinforced concrete (UHPFRC) jackets. Several experimental studies have investigated the application of UHPFRC jackets to strengthen or retrofit RC structural elements such as slabs, beams, and columns. These studies have produced several valuable insights, revealing that columns are exposed to continuous and sustained loads or experience atypical and unconventional load patterns. These loads can accumulate over time, potentially leading to partial damage or even complete failure of the column. Consequently, UHPFRC jackets have been employed to strengthen RC columns by increasing their load-carrying capacity and to retrofit damaged sections and weak regions in deteriorated RC columns, providing a practical approach to protecting infrastructural components and existing buildings. This paper aims to provide a comprehensive and detailed overview through a state-of-the-art review of different techniques for strengthening and retrofitting RC columns using UHPFRC jackets. Additionally, it presents the materials utilized to produce UHPFRC mixtures, as proposed by numerous researchers over the past two decades. Finally, the review paper identifies research gaps and proposes future research directions for strengthening and retrofitting RC columns using UHPFRC jackets. This includes investigating new UHPFRC mix designs, exploring long-term durability, studying the bonding behaviour between UHPFRC and existing RC columns, and developing practical design guidelines.