Assessing the potential of saw dust, ASH and lime as soil stabilizers in road construction Case of Karumuna to Jali Sector Headquarter road

Abstract

This study investigates the potential of sawdust ash and lime as soil stabilizers in road construction, specifically addressing the challenges posed by soils with high clay and silt content in the Karuruma to Jali Sector Headquarter road. The research aims to enhance the engineering properties of soil to ensure stability and durability in road construction. The specific objectives include assessing the effectiveness of sawdust ash and lime in improving soil properties, evaluating their impact on strength and durability, determining their sustainability and cost-effectiveness compared to traditional stabilizers, and identifying optimal mix proportions for achieving desired engineering characteristics. The problem of variable physical properties in clay-rich soils, which lead to instability and structural failures, necessitates the use of stabilizers. Traditional methods using cement and lime are widely adopted; however, the search for more sustainable alternatives is critical. The study employs standardized laboratory tests, including sieve analysis, Atterberg limits, compaction, and California Bearing Ratio (CBR) assessments, to analyze soil samples from the designated road. Results indicate that untreated soil is classified as high plasticity silt, presenting challenges for road stability. Laboratory findings reveal that the incorporation of sawdust ash and lime significantly improves compaction behavior, maximum dry density (MDD), and CBR values. Specifically, optimal proportions of 6% lime and 10% sawdust ash result in enhanced soil strength and reduced plasticity. The CBR values demonstrate marked improvement with sawdust ash, while lime consistently enhances soil strength under varying moisture conditions.

This research concludes that sawdust ash and lime are effective, sustainable, and cost- effective alternatives for soil stabilization in road construction, highlighting their potential

to improve the engineering properties of lateritic soils in Rwanda. The findings support the feasibility of implementing these materials in rural infrastructure projects. Future research

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should explore the long-term performance of stabilized soils under dynamic loading conditions to fully assess their viability for large-scale applications.