Incineration with energy saving is one of the principal technique used to treat urban wastes. The number of municipal waste incinerators is strongly increasing in the European community. Therefore the production and the valorisation of the by-products generated by these plants is essential, in particular the valorisation of the urban waste slags. The principal objective of the project is to find innovating techniques for re-using the municipal solid waste slags treated with hydraulic binders and placed as base or subbase courses for road. These innovating applications will open new economic markets located near the production centers, and will increase the quantities treated. A broad cooperation between the various operators (producers, users, industrials performing slag treatment) is necessary in order to resolve all the technical issues; consequently the different parameters and analytical methods must be define during the feasibility study.