The study has concentrated on residues in unbound road layers. The materials selected were processed municipal solid waste incinerator (MSWI) bottom ash, crushed concrete and air-cooled blast furnace slag (AcBFS). The deformation on loading the possible strength development over time and the resistance to mechanical and climatic action were studied in the laboratory and in the field The results were compared with those of the conventional aggregates they could possibly replace, such as sand, gravel and crushed rock. The methods used in the laboratory were cyclic load triaxial tests, Los Angeles tests, micro-Deval tests and freeze-thaw tests. In the field, test sections with residues and reference sections with conventional aggregates in the unbound layers were monitored by means of falling weight deflectometer (FWD) measurements.