Bio-additive stablization of clayey soil: ANN prediction and multi-objective genetic algorithm optimization

For centuries, plant-based materials have been used to enhance soil properties due to their low cost, availability, biodegradability, and renewability. This study examines the effect of two types of waste derived from Washingtonia filifera palm, leaf waste used in powdered form and biochar produced from rachis waste pyrolysed at 400 °C, on the physical and mechanical behaviour of clay soil.Both additives were alkali-treated with NaOH solutions of 2%, 5%, and 8% for 1, 4, and 7 h, and characterised by the X-Ray Diffraction (XRD) and the Thermogravimetric Analysis (TGA) analyses. Atterberg limits, Standard Proctor compaction, and unconfined compressive strength (UCS) tests were conducted.The ressults showed that the plasticity index decreases with leaf powder but increases with biochar. Both treatments reduced the optimum moisture content and increased the maximum dry density. UCS increased up to 3.1 times with 5% leaf powder after 28 days, while biochar yielded a continuous increase, reaching 4.7 times the initial value. Microstructural analysis confirmed improved particle bonding and soil structure. Furthermore, Artificial Neural Networks (ANN) were developed to model the experimental results, and a Genetic Algorithm (GA) was applied for optimisation. Overall, the use of Washingtonia filifera residues as bio-additives provides an effective and sustainable approach to clay soil stabilisation.