Some mechanical and durability properties of composite material produced with by-products of Orhaneli power plant (flue gas desulfurization sludge, fly ash and bottom ash), cement and hydrated lime were investigated. To improve the mechanical properties (compressive and flexural strength) of this material, steam curing was applied and the effect of chemical admixture (high water reducing agent) was investigated. Some physical properties and water resistance of the mixtures were also determined. Furthermore, microstructure of the specimens was investigated using scanning electron microscopy. Finally, to produce construction elements, prototypes of building blocks were manufactured by using some of these mixtures. All kind of power plant wastes (flue gas desulfurization sludge, fly ash, bottom ash) can be utilized with these mixtures, which consist of 90% of coal combustion byproducts. It seems to be a promising material for composite construction elements such as building blocks. (c) 2006 Elsevier Ltd. All rights reserved.