Background and Methodology

Prefabricated concrete structures can be found across the globe: in commercial, industrial, institutional, and residential buildings of all sizes. As the society around them has changed drastically compared to when they erected, many of these structures are approaching the end of their economic or functional lifespan. However, the lifespan of the concrete they are made of is far from over. These prefabricated and primarily load-bearing elements can have significantly longer lifespan if they remain protected from environmental agents and frost, in other words, are properly maintained and cared for in another construction cycle.

Figure 5 Steps of the reuse cycle for precast concrete as proposed in the ReCreate project. 

The methodology of ReCreate is multi- and interdisciplinary. Acquiring the necessary historical information on the potential urban mines (prefabricated building stocks) and their details draw from an archival and historical research approach but relies on digital data handling and visualization to store, process, and share this information. The technical part of the project takes advantage of technologies developed for other fields and applies them in the context of deconstruction and reuse in order to demonstrate and consolidate an integrated and cost-efficient value chain that can become profitable at an industrial scale.

Figure 6 Carbonation tests on samples from the Finish donor building. Carbonation plays an important role in the corrosion of the reinforcement and is therefore a good predictor for the remaining service life of a concrete building. 

The methodology further draws from the research of human and industrial processes and their optimization with the help of smart digital tools for surveying, tracking, and modelling. Technological solutions specific to deconstruction and reuse, such as equipment for neat disassembling and retrofit connectors, are innovated and engineered. Underlying the project’s technological focus is an understanding of the business sectors as networks of actors, both companies and individuals, and the values and beliefs that influence their actions.

Pilots: Germany, Finland, Netherlands, and Sweden

Four pilot donor buildings are currently in different stages of the step-by-step process towards reuse: pre-deconstruction auditing; deconstruction; storage; processing and quality control; transport; and finally, reassembly.

The German pilot consists of a partial dismantling of 36 residential units in two floors and with six entrances. The dismantling takes place while the rest of the building remains occupied, so the affected tenants have to leave the apartments during the dismantling work. The (re)construction of a youth center in Hohenmölsen with 800 m² GFA is planned for the end of 2023. In the course of the new construction, up to 150 dismantled concrete elements are to be reused.

Figure 7 The Finnish donor building before deconstruction. 

The dismantling is implemented with the help of two work teams (one in the building and the other on the ground), a crane driver and an excavator driver. The concrete elements are loosened from the building structure manually and also with mini excavators lifted by the crane, and carefully laid down. Elements that will not be reused are pre-crushed with a hydraulic pulverizer.

The donor building of elements for the Finnish reuse pilot is located in the City of Tampere, the third largest city in Finland, where ReCreate’s coordinator Tampere University is based. The donor structure is a 7-floor office building with circa 3,000 m² GFA, built in the early 1980s, with a fully prefabricated concrete frame: columns, beams, hollow-core slabs, and sandwich exterior panels. The building has been scheduled for removal due land use change from a commercial to a residential function. The plan in ReCreate is to deconstruct the prefabricated building frame, mainly focusing on the columns, beams, and hollow-core slabs, which have been protected from weathering by the building envelope.

The donor pilot in the Netherlands is called Prinsenhof A. It is an office building located in Arnhem city center. The building has a low-rise part (five stories), a high-rise part (nine stories) and a core that connects them. The total GFA is approximately 7,400 m². The building is owned by the province of Gelderland and was constructed in 1986. The structure consists of hollow-core slabs spanning 13 m between precast concrete load-bearing façade elements.

The precast elements will be used in the construction of two new buildings. About 80 hollow-core slabs will go into a new sporting center of the city of Arnhem. The remaining hollow-core slabs and the façade elements will be used for a new knowledge center for circular building and disassembly by Lagemaat.

Figure 8 Concrete elements deconstructed from the Dutch donor building. 

The Swedish pilot used prefabricated concrete elements from the Drottninghög neighborhood, where the municipal housing company Helsingborgshem owns a majority of the dwellings. The building from which the exhibited elements came was located at Kvarteret Drottninghög Västra 1. The apartment building, built in 1967-68, had a total of approximately 2,250 m² and contained 24 apartments. The structure was a bookshelf frame with transverse load-bearing inner walls of prefabricated concrete elements from the factory in Helsingborg.

The housing area Drottninghög is undergoing a 20-year process of regeneration and revitalization. Some original housing blocks from the 1960’s have already been demolished and some more are under review in the planning process. The ambition is to promote the careful reuse of concrete elements from the original housing in new future housing.

Figure 9 Construction of the Swedish pilot with reused elements from three different donors. 

Through the development of these four pilots, ReCreate aims to demonstrate the feasibility and profitability of reuse. This requires developing the technical expertise for reuse and the integration of technologies and workflows to facilitate the integration of different parts of the supply chain towards a circular economy.

Figure 10 The ReCreate project at the “Cycle”s exhibition (curators Pamela Prado, Pedro Alonso), part of Terra, Lisbon Architecture Triennale 2022. 

ReCreate

Project coordinator: Satu Huuhka, Tampere University, FI

Academic partners: BTU Brandenburg University of Technology, DE; Tampere University, FI; Eindhoven University of Technology, NL; KTH Royal Institute of Technology, SE

Project partners: BTU Brandenburg University of Technology (DE); Tampere University (FI); Eindhoven University of Technology (NL); KTH Royal Institute of Technology (SE); ECOSOIL Ost GmbH (DE); Dreetz und Partner (DE); P. Jähne Ingenieurbüro GmbH (DE); LIIKE Oy Arkkitehtistudio (FI); Consolis Group (FI); City of Tampere (FI); Ramboll Finland (FI); Umacon (FI); Skanska (FI); IMd Structural Engineers (NE); Lagemaat Design & Construction (NL); Helsingborgshem (SE); Croatia Green Building Council (HR), TNO (NL), Circular Structural Design (DE)