Hybrid Reinforcement of Traditional Bricks Using Opuntia ficus-indica cactus Fibers and Biochar: Optimization and Prediction via RSM and ANN

To address the pressing housing demand brought on by issues with population increase, earth construction materials with good mechanical and thermal qualities must be developed. To meet this objective, earth bricks were reinforced with a hybrid blend of Opuntia ficus-indica cactus plant (OFICP) fibers and biochar obtained through the pyrolysis of the same plant. The fibers, incorporated at 0.5% and 1% by weight, underwent alkaline treatment using sodium bicarbonate (NaHCO₃) at concentrations of 5%, 7%, and 10%, with immersion durations of 24, 72, and 168 hours. The multiple nonlinear regression models RSM et ANN were generated utilizing variables such fiber content, immersion time, and NaHCO3 content in order to predict compressive and flexural strength as well as thermal conductivity. According to the findings, 0.5% fibers treated with 7% NaHCO3 for 72 hours constituted the ideal formulation. The mix’s workability was much improved by the addition of biochar. However, these mechanical characteristics gradually decreased as the fiber content increased above this level. Thermal conductivity dropped from 0.64 W/m·K in specimens without OFICP fibers to 0.37 W/m·K in those with 1% OFICP and biochar, demonstrating a significant decrease in heat transmission as a result of fiber inclusion and an improvement in thermal insulation.