Sustainable strengthening of RC beams using ferrocement with recycled clay bricks: Role of areca nut husk and jute fibres

Ferrocement is a thin, lightweight composite material composed of cement mortar reinforced with layers of steel mesh. This technique is also cost-effective, enabling the use of recycled waste materials, which promotes sustainability and environmental friendliness. It offers high tensile strength, crack resistance, and durability, making it suitable for repairing and strengthening concrete structures. However, plain cement mortar may not bond well with steel wire mesh and could exhibit issues such as reduced ductility, brittleness, and debonding, which need to be thoroughly understood. To this end, this research evaluated 20 damaged reinforced concrete (RC) beams strengthened with ferrocement and compared their performance to that of an unstrengthened beam (USB). The ferrocement mortar mixtures included 100 % natural sand (NS) and a blend of 50 % recycled crushed clay brick (RCCB) with 50 % NS (50–50 RCCB-NS). Additionally, different proportions of jute fibre (JF) and areca nut husk fibre (ANHF) were used, specifically, 0 %, 0.25 %, 0.5 %, and 1 %, at two water-to-cement (w/c) ratios of 0.30 and 0.50. Two data-based models were developed for all the beams and optimised using experimental data, with the results compared to existing literature. The findings demonstrated that JF and ANHF significantly improved both the flexural load capacity and ductility of the damaged beams compared to USB. For instance, the flexural load was enhanced by 21–59 % for JF, 42–59 % for ANHF when using 100 % NS and 13–63 % for JF, 42–55 % for ANHF, meanwhile using 50–50 RCCB-NS at w/c of 0.30, higher than USB. At the same time, the deflection achieved 111–196 % for JF and 66 % for ANHF when using 100 % NS and 53–93 % for JF while using 50–50 RCCB-NS at w/c of 0.30, higher than USB. The data-driven model closely matched the experimental load-deflection behaviour, including crack progression, while the optimisation model aligned well with the test results. Furthermore, the model accurately predicted findings from the existing literature. The research suggests that using 0.25–0.5 % JF or ANHF with w/c ratios of 0.30 and 0.50 results in optimal performance, contributing to reduced CO2 emissions and promoting sustainability.