The ongoing project TAREC2 , which deals with the transformation of wood ash waste into construction materials, is already showing interesting results. Woody and agricultural biomass are among the highest biomass potentials for energy production as a sustainable fuel. This will lead to the production of a foresee amount of 15.5 million tons of biomass ash in the EU - 28, which will double its current amount. Presently, most ashes in Europe are landfilled, causing financial and material losses as well as an environmental burden. In general, biomass ash composition and properties are highly variable depending on: 1) type of base - biomass feed stock, 2) geographical location, 3) combustion technology (e.g. fixed bed, or pulverized fuel boilers). Further classification of ashes is done by type of collection from a boiler. A possible application for biomass ash is as a cement and/or sand replacement in cementitious materials. However, some standards (e.g. EN 450 - 1) prohibit the use of biomass ash in the concrete. This fact results in rising costs for the biomass ash waste management that forces power plant owners to search new opportunities to recycle ashes. Therefore, within the framework of the TAREC2 project, a partial replacement of cement with fly ash waste generated by burning forest residues and waste wood from the timber industry is being researched. Thus, potential reuse of ash could reduce landfilling and at the same time improve the sustainability perspective of cement production, by reducing energy needs for cement production, cutting back in CO2 emissions, and preserving natural resources (i.e. limestone) with no concern for depletion of biomass ash supplies.