Evaluation of Sawdust Ash-Stabilised Lateritic Soils for Low-Cost Urban Road Construction and Sustainable Cities (Published)
The increasing demand for sustainable and affordable urban road infrastructure has heightened interest in alternative soil stabilization materials made from waste products. Lateritic soils are commonly used as subgrade materials in tropical areas; however, their high plasticity, moderate strength, and moisture sensitivity often limit their performance. This study assesses the effectiveness of sawdust ash (SDA) as an environmentally friendly stabilizing agent for lateritic soils used in low-cost urban road construction. To achieve this, lateritic soil samples were collected from selected borrow pits in Ile-Ife, Osun State, southwestern Nigeria. Standard procedures were used to perform preliminary and geotechnical tests on the natural soil samples. SDA was added to the soil samples at 3%, 6%, and 9% by weight of dry soil to identify the optimal stabilization level. The treated soil samples then underwent CBR testing. Results indicated that adding SDA reduced soil plasticity, signifying decreased swelling potential and better workability. The addition of SDA also increased CBR values, with the highest results at the optimal stabilization levels, indicating improved load-bearing capacity. This enhancement is due to pozzolanic reactions between silica-rich SDA and calcium compounds in the soil, resulting in the formation of cement-like products that strengthen the soil. The findings demonstrate that SDA is a practical and environmentally sustainable stabilizer for lateritic soils. Reusing SDA not only improves geotechnical performance but also supports waste management and reduces environmental pollution. This study advocates for the use of SDA stabilization in sustainable urban road development.
Keywords: California Bearing Ratio, road construction, sawdust ash, sustainable cities, urban development