URBCON reduces the use of raw materials and the CO2 emissions from construction and maintenance of buildings and infrastructure in cities.The URBCON project targets the use of concrete as a building material. With the focus on the metropolitan areas of Ghent, Rotterdam and Northern France, by-products such as metallic slags and incineration ashes are used as alternative raw materials for the production of concrete. Replacing primary raw materials with by-products could save an estimated 84 million tonnes of mineral building materials per year.