Geotechnical Evaluation of Sawdust-Derived Biochar as a Sustainable Stabilizer for Clayey Soils in Nueva Ecija

Abstract

This research investigates the potential of sawdust-derived biochar as a sustainable soil stabilizer for clayey soils in Nueva Ecija, Philippines. Conventional stabilizers, such as cement and lime, are associated with high carbon emissions, prompting interest in environmentally friendly alternatives. In this study, sawdust—a common agricultural byproduct—was converted into biochar and mixed with clay soil at varying proportions (0%, 5%, 10%, and 12% by weight). Laboratory evaluations included Standard Proctor Compaction, California Bearing Ratio (CBR), and Direct Shear Tests. The 10% biochar content emerged as the most attractive content of biochar for improvement in shear strength and compaction characteristics, while 12% contributed to minimizing the swelling potential. However, even with such improvements, none of the CBR values termed the subgrade suitable, thus indicating biochar is better used as a supplemental stabilizer. It is concluded that sawdust biochar is a promising material for sustainable geotechnical applications, especially when mixed with other stabilizing agents.