Authors: S.O. Subair, H. Solihu, G. A. Lawal, A.O. Yusuf, A. A Olododo
Abstract: Lateritic soils are widely used as construction materials for highways, embankments, foundations, airfields, and earth-retaining structures in Nigeria. However, these soils often exhibit inadequate engineering performance, leading to challenges such as pavement deterioration, excessive settlement, erosion, slope failure, and seepage. Soil stabilization has therefore become essential for enhancing their geotechnical characteristics and ensuring structural durability. This study investigated the effectiveness of sawdust ash (SDA) and plantain peel ash (PPA) as environmentally sustainable stabilizing agents for improving the engineering properties of lateritic soil classified as AASHTO A-2-6. The soil was treated with varying proportions of SDA (3%, 6%, 9%, and 12%) combined with a constant 6% PPA. Laboratory tests were conducted to evaluate the effects of stabilization on the soil’s properties. These tests included moisture content determination, particle size distribution, Atterberg limits, compaction characteristics, and California Bearing Ratio (CBR). The results showed that the addition of SDA and PPA improved the index and strength properties of the soil. Maximum Dry Density (MDD) increased with increasing stabilizer content, while Optimum Moisture Content (OMC) also exhibited an upward trend. Furthermore, CBR values improved significantly, indicating enhanced load-bearing capacity suitable for use as fill material, subgrade, and subbase layers in pavement construction. Among the stabilization levels investigated, the combination of 9% SDA and 6% PPA produced the most favorable performance. The findings suggest that incorporating SDA and PPA can effectively improve weak lateritic soils while promoting the beneficial use of agricultural waste materials in geotechnical engineering applications.
Keywords: California bearing ratio, lateritic soil, optimum moisture content, plantain peel ash, saw dust ash