"The new building products that have been recovered include mortars, fresh concrete and prefabricated products, among others"
TECNALIA is involved in the RSU4HOM initiative, aimed at turning urban slag into new building products
The RSU4HOM initiative, developed under the HAZITEK programme, led by FCC Medio Ambiente, has completed its third year with a promising results: turning urban slag from municipal solid waste (MSW) incineration into new building products, such as mortar, fresh concrete and prefabricated concrete.
This innovative initiative, in which companies in the sector such as EDERRA, Prefabricados Leceaga, Kobeka Harrobiak, and technology centres like TECNALIA and CERTINALIA have actively collaborated, came about with a clear circular economy objective: to recover waste that usually ends up in landfills and transform it into a useful raw material for civil works.
From waste to resource
The aim of the initiative has been the study and characterisation of MSW slag as a possible aggregate for mortar and concrete. Numerous physico-chemical and mechanical performance tests have been carried out to assess its technical and environmental feasibility.
The results are encouraging: the slag complies with most of the requirements set out in European standards (UNE and EN), showing adequate performance in terms of resistance, granulometry and stability. However, certain limitations have been detected in aspects such as alkali-silica reactivity or the proportion of fine ...., which are already being addressed through optimisation processes and blending with natural aggregates.
Innovation with impact
In addition to laboratory studies, RSU4HOM has included the manufacture of real prototypes of mortars and prefabricated concretes using recycled slag, enabling their performance to be validated under real conditions.
However, the initiative is not only technical: an exhaustive assessment of its economic viability and environmental impact has also been carried out, estimating that its implementation could reduce the construction sector’s carbon footprint and contribute to a more efficient management of urban waste.
Towards more circular construction
RSU4HOM represents a firm step towards a more sustainable construction model, aligned with the principles of the circular economy. Thanks to the backing of programmes like HAZITEK, the Basque consortium has proven that it is possible to close the urban waste cycle, integrating it back into the industrial value chain.
The initiative leaves the door open for future industrial scaling-up and the possibility of its replication in other territories, such as France, where the environmental costs of waste transport are also critical.
Furthermore, the advances and solutions developed within the framework of RSU4HOM have been presented at the Basque Circular Summit 2025, one of the leading circular economy events in southern Europe. The consortium shared its experience and results with a specialised audience, confirming the Basque Country's commitment to sustainable innovation and waste recovery as a lever for ecological transition.
