An EU-funded project has developed prefabricated energy-efficient building concepts made from materials, components and structures derived from construction and demolition waste. The concept enables the easy assembly and disassembly of buildings for future reuse.


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© Ambrose #863692 source: stock.adobe.com 2020

The construction industry is an important driver of European prosperity. However, it is also a major consumer of raw materials and produces large amounts of construction and demolition waste (CDW). These are key challenges identified by the Europe 2020 strategy, which requires EU Member States to reuse, recycle and recover a minimum of 70 % by weight of non-hazardous CDW.

This target could be achieved by constructing and refurbishing buildings using CDW. The EU-funded RE4 project demonstrated how this can be done.

‘RE4 contributed to reaching the target for CDW recycling/recovery by 2020 by providing innovative technologies and reliable strategies for the design and manufacture of structural and non-structural pre-fabricated elements, with a high degree – up to 85 % – of recycled materials, and by reusing structures from the partial or total demolition of buildings,’ says project coordinator Alessandro Largo of CETMA, Italy.

Four pillars

The project’s solutions were integrated, validated and showcased in the construction of two-storey demonstration buildings at project partners’ premises, ACCIONA in Spain and CREAGH in the UK. In Spain, the project also demonstrated the strategy for disassembly and reuse of structures from end-of-life buildings.

The team showed how CDW-derived structures and materials, such as concrete, timber, roof tiles and bricks, can be used to produce prefabricated, fully reusable buildings. RE4’s success was built on four pillars: maximising the amount of valuable materials recovered; designing reusable building components; improving CDW management through digitisation; and increasing the acceptance of CDW-based products.

An advanced robotic sorting system was developed during the RE4 project to improve the quality of sorted materials, the main focus being on those with high economic value such as sand. The project team also defined new quality classes for CDW-derived aggregates and identified optimal recycling strategies for each of them.

This led to the production of five new concrete materials with different properties, four new components (blocks, tiles, timber and insulating panels), and four new prefabricated elements (concrete and timber façade panels, load-bearing concrete elements and internal partition walls). In all these products, 50-85 % of new material was replaced with recycled elements.
RE4’s innovative building concept, using prefabricated, easily dismountable components, enables a new house to be built with up to 100 % reusable structures.

The project’s approach can also be used to refurbish existing houses. RE4 solutions for refurbishment were applied to existing buildings in Italy and Taiwan, taking into account climatic and structural factors in different geographical zones. The seismic performance of RE4‘s innovative solutions was verified through shaking-table testing.

Building on the benefits

The new materials and components derived from CDW have lower environmental impacts than conventional ones, with more than 50 % saving in terms of CO2 emissions, and savings in the consumption of energy and raw materials. They are also more than 20 % cheaper to produce.

Industry partners can therefore take a competitive advantage in leading the transition towards a circular economy in the construction and demolition sector. They can make demolition more economically viable, for example, and ensure the quality of resulting secondary raw materials. Benefits are also derived from standardised production increasing efficiency, and through the fulfilment of requirements for green buildings. Moreover, RE4 solutions can generate new green job opportunities and businesses.

‘The RE4 project has demonstrated how CDW-derived materials and structures can be effectively reintroduced in the production cycles of concrete and timber components with a replacement rate of 50-85 %. Moreover, from a technical point of view, a fully prefabricated, 100 % reusable building is now a reality,’ says Largo.

‘The way is being paved but there is still a strong need to improve waste identification, separation and collection at source, quality assessment procedures and, mainly, policy and framework conditions to foster the transition to a circular economy in construction,’ he concludes.



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