Effects of Using Sawdust Ash as a Stabilizer for Expansive Soils

¹ Department of Civil Engineering International University of East Africa, P.O. Box 35502, Kampala, Uganda
² Department of Civil Engineering and Technology, Sirindhorn International Institute of Technology, Thammasat University, Pathum Thani, 12120, Thailand

^* Corresponding author: niyojayb1992@gmail.com

Abstract

Expansive soils are known to swell and shrink with moisture content changes, rendering them unsuitable for construction without proper stabilization. Cement and lime have conventionally served as common additives for soil stabilization. However, in Uganda, the escalating costs of these additives accentuate the need for alternative solutions. Therefore, this research attempts to investigate the viability of sawdust ash, an affordable agricultural waste, as an effective stabilizer for expansive soils. Through systematic experimentation, various percentages of sawdust ash (ranging from 0% to 10%) were introduced into the soil matrix. The objectives of the study were achieved through a series of laboratory tests, including gradation analysis, Atterberg limit determination, compaction, and California Bearing Ratio (CBR) test. The findings revealed the soil is clay with high plasticity, emphasizing the need for stabilization. Importantly, the addition of sawdust ash resulted in a substantial reduction in the plasticity index, from 35% to 16%, at 0% and 10% sawdust ash content, respectively. Furthermore, the incorporation of sawdust ash led to an increase in the maximum dry density and a reduction in the optimum moisture content as its proportion was augmented. Notably, with 6% sawdust ash content, the CBR value reached its highest point at 14.4%. These outcomes reveal the potential of sawdust ash as an economically attractive alternative to traditional stabilizers such as cement and lime. This research contributes valuable insights to the field of soil stabilization and offers a sustainable solution that addresses both economic and environmental concerns in construction practices.