application 0f sewage sludge ash to improve engineering properties of clay soil in water structures

different additives have been considered to improve stabilization of the engineering properties of fine-grained soil. the present study investigated the effect of the addition of sewage sludge ash on the compressive strength of clay soil at optimum moisture content and under saturated conditions. the four treatments tested were the addition of 0%, 5%, 10% and 15% sewage sludge ash to clayey soil. the compaction characteristics of the treatments were determined using a harvard compaction test. then 24 specimens from each treatment were prepared at curing times of 7, 14, 28 and 90 days. testing included three replications for a total of 96 specimens created using a harvard compaction mold. the specimens were subjected to unconfined compressive strength tests. the results showed that increasing the sewage sludge ash content of the soil decreased the maximum dry unit weight and increased the optimum moisture content. the compressive strength of the soil treated with sewage sludge ash increased for both the optimum moisture and saturated conditions. it was found that the compressive strength of the treated soil significantly increased as the curing time increased.