Publication: Strengthening and retrofitting of rccolumns with ultra-high performance fiber-reinforced concrete jacketing
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Date
2024-08-01
Authors
Mohammed Abdullah Ali, Mohammed Al Amoodi
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Abstract
Despite extensive prior research, ongoing debates persist regarding the efficacy of utilizing special concretes. Specifically, those incorporating silica fume, fly ash, and forta-ferro polypropylene fibres (FFPF) in enhancing the performance of reinforced concrete (RC) columns. previous studies often failed to comprehensively address critical parameters influencing column behaviour, such as variations cross-sectional shapes of the columns, varying thicknesses of the UHPFRC jackets applied, and the ratios of transverse and longitudinal steel reinforcement ratio, simultaneously. The incorporation of silica fume, fly ash, and FFPF in concrete mixtures has the potential to enhance important characteristics of the concrete, including its load-bearing capacity, ductility, flexural strength, energy dissipation abilities, and overall strain capacity when subjected to unusual or extreme loading scenarios. This study conducted experimental investigations to assess the influence of incorporating silica fume, fly ash, and forta-ferro polypropylene fibres into concrete mixture on the retrofitting and strengthening capabilities of pre-damaged as well as non-damaged reinforced concrete (RC) columns. Accordingly, the study identified an appropriate concrete mixture composition that includes approximately 25% silica fume (by cement weight), 10% fly ash (by cement weight), and 2% of straight micro forta-ferro polypropylene fibres (with aspect ratios of 65 and 85). A total of 54 column specimens were prepared and tested, those specimens were divided into three groups based on the shape of a cross-section into 18 rectangular, 18 square columns, and 18 circular columns. More specifically, 12 specimens as a controlled column and 42 specimens as a confined column with UHPFRC jackets (20 mm, 30 mm, and 40 mm jacketing thicknesses). The experimental results for the jacketed columns revealed that, in comparison to the control columns, there was a substantial increase in deflection beyond the maximum load, reaching up to 200%. This resulted in a significant improvement in the structural ductility factors, increasing by up to 44%. These enhancements were achieved by incorporating silica fume, fly ash, and forta-ferro polypropylene fibres into the concrete mixture. In conclusion, UHPFRC jackets can be used as an eco-friendly building material for retrofitting and strengthening reinforced concrete (RC) columns and enhancing the ductility of columns as a new retrofitting strategy.