EFFECT OF BRITISH STANDARD HEAVY EFFORT ON THE LATERITIC SOIL STABILIZED WITH STONE DUST ADMIXED WITH LIME AS A MATERIAL IN PAVEMENT CONSTRUCTION

This study investigated the stabilization of lateritic soil using lime and stone dust under British Standard Heavy (BSH) compactive effort to improve its performance in pavement construction. Soil samples were collected from Iree-Obagun in Osun State and treated with varying proportions of lime and stone dust. To evaluate the effects of stabilization, geotechnical and microstructural tests including Atterberg limits, compaction, unconfined compressive strength (UCS), California Bearing Ratio (CBR), X-ray fluorescence (XRF), and scanning electron microscopy (SEM) were carried out. The natural soil was reddish-brown with a moisture content of 18.23%, a specific gravity of 3.16, and a plasticity index of 17%. Classification results identified it as A-2-7(0) under AASHTO and SM under USCS, confirming its poor natural suitability for pavement works. Compaction results revealed that maximum dry density increased from 1.64 Mg/m³ to 2.34 Mg/m³ at 2% lime and 15% stone dust, while optimum moisture content decreased from 17.7% to 13.43%. The soaked CBR value increased from 34.45% for the untreated soil to 79.84% at the optimum mix, while the unsoaked CBR rose from 38.71% to 82.38%. Similarly, the UCS improved from 260.31 kN/m² to 410.97 kN/m². However, results indicated that strength declined when lime and stone dust were added beyond the optimum content. XRF results showed that lime contained high calcium oxide, while stone dust was rich in silica and alumina. SEM images showed that the soil changed from porous to denser, with cement-like products (C–S–H and C–A–H). The study concludes that lime and stone dust are effective stabilizers for lateritic soils, with optimum performance achieved at 2% lime and 15% stone dust.