A laboratory experimental study was carried out to explore the possibility of using sewage sludge ash (SSA) and fly-ash (FA) with soil for improving the soil engineering properties that can be used in engineering applications. Primarily, four engineering properties tests: grain size distribution, proctor compaction, Atterberg limits, and unconfined compressive strengths (UCS) for several arbitrarily selected curing periods were conducted for soil samples mixed with SSA and FA together. The test results revealed that the mixing of soil with SSA-FA together improved the soil type and the soil engineering properties. The UCS increased substantially for both the soil samples mixed with 7.5%SSA-50%FA and 10%SSA-40%FA for a curing period of 28 days. Potentially 7.5 – 10% of SSA and 40 – 50% of FA can be utilized as a beneficial use when mixed with appropriate soil in combination of SSA-FA that would otherwise go to landfill. Overall, the application of SSA-FA mixing with appropriate soil type could be a viable alternative management route for both the wastes and provide a potential sustainable engineering construction material.

Keywords: Management of SSA and FA, Fly-ash, Sewage Sludge Ash, Soil Improvement, Engineering Properties.