PERFORMANCE EVALUATION OF MULTI-ADDITIVE WASTE MATERIALS FOR SUSTAINABLE SOIL STABILIZATION

Problematic clay soils commonly found in tropical environments are frequently characterized by excessive plasticity, low shear strength, and inadequate bearing capacity, which restrict their direct use in pavement and foundation construction. This study investigates the effectiveness of a hybrid stabilization approach using MHA, QD, and BG as sustainable alternatives to conventional stabilizers. Laboratory evaluations comprising Atterberg limits, compaction characteristics, unconfined compressive strength (UCS), California bearing ratio (CBR), and microstructural assessment using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) were performed. MHA enhanced soil performance through pozzolanic reactions and cementitious bonding, QD improved packing density and particle interlock, and while BG contributed to load transfer and shear resistance by forming a granular skeleton. The combined application of 5% MHA, 15% QD, and 25% BG produced a marked synergistic effect, increasing UCS from 289 to 1459 kPa and CBR from 4.2% to 13.2%. Microstructural observations confirmed a dense matrix with reduced pore spaces and improved interparticle bonding. The findings demonstrate that multi-additive stabilization using agro-industrial waste materials provides a technically effective and environmentally sustainable solution for improving weak clay subgrades.