For highly urbanized cities where there is a scarcity of available land for landfilling, incineration may be a better method of solid‐waste disposal. After incineration about 20% by weight of ash and other residues are produced. Both the washed clinker and fly ash collected from the refuse‐incineration plant have the prerequisite properties for use in geotechnical applications. The washed clinker is essentially a granular material of irregular shape. Fly ash is predominantly silt‐sized, spherical particles. The specific gravities of the washed clinker and fly ash are 2.67 and 2.45 respectively. Both materials exhibit high strength and are relatively free‐draining, typical of granular materials. The fly ash could be used as an admixture in the stabilization of soft soil. The clay samples treated with fly ash show substantially improved shear strengths and lower compressive properties.