Comparative Evaluation of Cement, Sawdust Ash and Maize Husk Ash in Stabilization of Dumpsite Soil in Oyo, Southwestern Nigeria

Abstract

The progressive increase in the waste generation and deposition in dumpsites has led to severe degradation of the environment. These degradations include reduction in the geotechnical properties of soil due to prolonged leachate infiltration thereby unfit for engineering purposes without adequate stabilization. The research compares the performance of more sustainable and readily available material such as agricultural waste (sawdust ash and maize husk ash) with cement in dumpsite soil stabilization in line with the 2030 agenda of sustainable development goals. Soil sample and waste ashes were prepared and the soil are treated with 0%, 6%, and 12% of each stabilizer and subjected to standard laboratory tests including Grainsize, Atterberg limits, compaction, unconfined compressive strength (UCS), direct shear, and permeability analyses. Also, X-ray fluorescence spectrometry was used to determine the major oxides in the waste ashes. Results showed that cement, with highest percentage of calcium oxide (CaO) produced the most significant improvement in strength and stiffness, increasing UCS from 4.6 kN/m² to 15–17.6 kN/m² and raising friction angles to 44.8°–50.6°. Sawdust ash demonstrated effectiveness in reduced deformability, achieving UCS values of 10.2–12.9 kN/m² and friction angles of 42°–47°. The findings indicated a multidimensional performance hierarchy: cement remains the most effective stabilizer for engineering construction; Sawdust ash serves as a viable, lower-carbon partial replacement for enhancing stability and deformation resistance; and Maize husk ash is best suited as a partial replacement for environmental protection where controlled permeability is the primary criterion.