Soft soil stabilization using sewage sludge ash

This study investigate on the potential of using sewage sludge ash to improve the shear strength parameters of soft soil. The sludge ash was obtained by burning the sludge for 1 hour at 800 °C. In this research, the following laboratory tests were conducted on the soft soil which are sieve analysis, standard proctor compaction, specific gravity, Atterberg limit and direct shear test. Two curing times were used for the untreated soils and treated soils with sludge ash which are 7 days and 14 days. The sludge ash was mixed with the soil at different percentages by weight of the soil at 2%, 4% 8% and 16%. The results showed that the increment in the sludge ash up to 8% increase both shear strength parameters which are cohesion and friction angle at 7 days curing time. Further increment of the sludge ash resulting decreases the cohesion values. The outcomes were observed present a better performance of the shear strength parameters at 7 days curing time. The findings of this research indicate that sludge ash can be applied to stabilize the soft soil and further diminish the environmental hazard associated with this material.