Characterisation of incinerator ash treated expansive soils

This paper investigates the physical, engineering, chemical and microfabric characteristics of two soils from Oman treated with incinerator ash produced at Sultan Qaboos University. First, the physical, engineering and chemical properties of the incinerator ash and the soils used were determined. The soils were then mixed with the incinerator ash at 0%, 10%, 15%, 20%, 25% and 30% by dry weight of the soils. Liquid limit and plastic limit tests were performed on specimens after 24 h of curing, whereas tests for swell per cent and direct shear were carried out on specimens cured for 1, 7 and 14 days. In addition, scanning electron microscope micrographs of representative treated samples were taken to examine the microfabric changes caused by the addition of the incinerator ash. The results showed that the incinerator ash used was a non-hazardous waste material. All treated samples showed a reduction in swell per cent and cohesion, and an increase in angle of internal friction with the addition of incinerator ash for all curing periods. The use of 20% and 30% additive showed clearly the development of aggregations that contributed to reduction of swell per cent of the soils.