Experimental and Theoretical Study on the Flexural Enhancement of Rice Sack Waste FRP-strengthened RC Beams

Reinforced concrete beams deteriorate over time due to design errors, substandard materials, improper construction practices, overloading, and long-term effects such as creep and shrinkage. Fibre-reinforced plastic (FRP) is widely used for strengthening, but its production raises environmental concerns. Meanwhile, plastic waste such as rice sacks is increasingly abundant in Indonesia and offers potential as a sustainable fibre material. This study explores the use of rice sack waste–based FRP composites for flexural strengthening of reinforced concrete beams. Beams were externally bonded with varying numbers of FRP layers, and their performance was evaluated through experimental flexural testing and theoretical predictions using ACI 440.2R-17. The results demonstrate that the waste-based FRP composites can enhance beam capacity, with effectiveness influenced by the number of layers applied. While ACI 440.2R-17 successfully predicts the general strengthening trend, it consistently overestimates the actual capacity observed in experiments. These findings indicate that the guideline is useful as a reference but requires refinement to better capture the behaviour of sustainable FRP composites in practical applications.