Role of recycled crushed clay bricks as fine aggregates in enhancing the performance of ferrocement-strengthened RC beams

Ferrocement is a highly effective composite material for enhancing damaged-reinforced concrete (RC) structural elements thanks to its excellent fracture resistance, tensile and flexural strength, crack resistance and durability. This material is applied in thin layers of cement mortar reinforced with steel wire mesh. The resulting structures are strong, lightweight, and cost-effective while allowing for incorporating recycled materials, promoting sustainability and environmental friendliness. Inspired by the outstanding performances of this technique, this study investigated 20 RC beams strengthened using ferrocement. Ferrocement mortar was fabricated with five various substitute rates (0–100 %, with 25 % incremental) of natural sand (NS) by recycled crushed clay brick (RCCB) and two water to cement ratios (w/c) of 0.30 and 0.50. Compressive, tensile, and flexural strength, and porosity of the mortar, were also investigated. In addition, a data-based model was developed and validated with experimental results. A significant enhancement in flexural resistance was recorded for the strengthened beam with up to 50 % RCCB than the unstrengthened beam-USB (15 % and 6 % for w/c of 0.30 and 0.50, respectively, higher than USB), which is aligned with the substantially higher mechanical strength and lower porosity of mortar. It was registered that the damaged beams strengthened with 50 % RCCB were able to nearly reach the stiffness of the USBs and deliver higher deflection (81 % and 31 % for a w/c of 0.30 and 0.50, respectively, higher than 100 % USB) with ductile failure induced by multiple flexural and diagonal cracks. The proposed data-based modelling achieved excellent results, accurately predicting the beams' load deflection and the mortar mixes' strengths and porosity.