Abstract
Lateritic soils are widely used in tropical pavement construction but often exhibit high fines, plasticity, and moisture susceptibility that undermine long-term performance. This study synthesizes engineering, chemical, and microstructural evidence from a lateritic soil stabilized using stone dust (SD) and bamboo leaf ash (BLA) to assess (i) moisture-related durability indicators and (ii) mechanistic–empirical (M–E) performance implications relevant to cyclic traffic loading. Lateritic soil was treated with SD (0–30% at 5% intervals) and with combined SD-BLA blends (BLA: 3 to 9%; SD: 5 to 20%) and tested for Atterberg limits, compaction (BSL/WAS/BSH), soaked and unsoaked CBR, UCS, and shear strength. XRF confirmed the pozzolanic character of SD and BLA (SiO₂+Al₂O₃+Fe₂O₃ = 85.51% for SD; 66.71% for BLA), while XRD/SEM evidenced microfabric densification and cementitious bonding in stabilized blends. The combined SD–BLA blend provided the best overall performance, with an optimum at 10% SD + 3% BLA (by dry soil mass), reducing plasticity (PI down to ~10%) and increasing strength. Moisture durability improved substantially: under British Standard Heavy (BSH) compaction, soaked California bearing ratio (CBR) increased from ~18% (natural) to ~65.48% (SD-BLA optimum) and the CBR retention ratio (soaked/unsoaked) improved from ~0.44 to ~0.71. For M-E interpretation, resilient modulus was conservatively estimated from CBR using a standard correlation, indicating a marked increase in wet-condition stiffness and reduced rutting susceptibility, thereby improving seasonal performance of subbase layers. These results support SD-BLA as a low-carbon stabilizer system for lateritic pavement layers, while highlighting the need for follow-on repeated-load and wet-dry cycling to fully quantify cyclic durability.