ReCreate project - Recreate

November 22, 2024
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Jakob Fischer, Brandenburg University of Technology

As Europe strives to meet its sustainability targets, the construction industry’s environmental impact is under increasing scrutiny. The sector is responsible for a significant portion of Europe’s resource consumption and waste generation. A key solution lies in evaluating building stock for its potential to contribute to circular economy practices, particularly through the reuse of construction materials like prefabricated concrete components. By reducing waste and conserving resources, this approach can help achieve the European Union’s (EU) climate and sustainability goals.

Europe’s Sustainability Goals and the Construction Industry

The European Union has committed to several ambitious targets, primarily through the Sustainable Development Goals (SDGs), including Goal 9 (Industry, Innovation, and Infrastructure), Goal 11 (Sustainable Cities and Communities), and Goal 13 (Climate Action). These goals promote building resilient infrastructure, reducing waste in urban environments, and taking urgent action on climate change.

In parallel, European policies such as the Circular Economy Package, the EU Waste Hierarchy, and the European Green Deal aim to curb resource extraction and promote material reuse. The building construction industry, as one of the largest consumers of resources and generators of waste, is central to these efforts. By recovering reusable concrete elements from existing structures, the sector can reduce its carbon footprint and contribute to Europe’s climate neutrality goal by 2050. The ReCreate project is developing numerous implementations to achieve these contribution goals.

Assessing Building Stock for Reuse

Evaluating building stock involves analyzing existing structures to identify materials that can be reused in new construction projects. This is especially important as Europe’s built environment contains vast amounts of materials, particularly concrete, that can be repurposed instead of discarded. The work package 1 of the ReCreate project is developing an analysis and mapping of existing precast concrete systems and elements.

Prefabricated concrete components, which are common in many buildings, offer substantial potential for reuse. These modular elements can be removed, inspected, and repurposed in new projects, reducing the need for energy-intensive production of new materials. Since concrete production is responsible for a large share of carbon emissions, reusing elements as a whole can significantly lower the environmental impact of the construction industry. Emission reductions of up to 98 % in comparison to virgin material prefabricated concrete elements, can be saved by reusing existing elements.

Urban Mining and the Circular Economy

Urban mining is a key element in transitioning towards a circular economy, where resources are reused rather than discarded. Buildings, especially those built in the mid-20th century, contain prefabricated concrete components that are still in good condition and suitable for reuse. Rather than allowing these materials to become waste, urban mining enables their recovery, helping reduce construction and demolition waste (C&DW).

C&DW represents nearly 40% of the total waste produced in the EU, underscoring the pressing need for robust waste management strategies. By reusing concrete elements as a whole the construction industry can contribute to a significant reduction in CO2 emissions. With concrete production accounting for up to 8% of global carbon emissions, any reduction in its demand has a meaningful impact on climate change mitigation.

Overcoming Challenges in Building Stock Evaluation

While the reuse of building components offers significant sustainability benefits, several challenges remain. On the one hand the structural and architectural integrity of reusable concrete elements have been testified and is being proven within the ReCereate project, however no market for reused elements has been developed yet, which could satisfy the demand of sustainable re-construction. Hence, the working packages 1 and 6 with the deliverable 6.2 will give an overview of the distribution and amount of defined elements in the existing building stock.

Another challenge is to evaluate the needed information for exact types of elements in existing buildings from national building stock databases. With the support of building owners (e.g. providing information on their building stock), reviewing literature and archives on construction/production activities in the past and assessing the current and future demolition rate, a more accurate assessment of the building stock will be investigated.

A centralized database tracking reusable materials across Europe could further enhance urban mining efforts. By cataloging the types, quantities, and conditions of reusable components, such a system would allow construction companies to plan projects more efficiently, ensuring that recovered materials are utilized effectively. Parts of these efforts will be achieved within ReCreate.

Conclusion

The systematic evaluation of building stock and the adoption of urban mining practices can contribute significantly to Europe’s sustainability efforts. Reusing materials like concrete supports SDG 9 by promoting resource-efficient infrastructure. It also aligns with SDG 11 by reducing urban waste and improving resource management, while contributing to SDG 13 by helping reduce the carbon emissions associated with new construction.

Achieving this requires collaboration between policymakers, industry professionals, and researchers. Governments can implement the regulatory frameworks and incentives needed to make reuse the norm, while construction professionals must adopt new approaches that prioritize resource recovery. Also building owners should be sensitized, to regularly evaluate their building stock, keeping track of their own ‘urban mine’ and step forward to interested planners and stakeholder in the construction industry with their upcoming potential of deconstructable and reusable concrete elements.

The future of Europe’s construction industry is circular, and evaluating building stock is a key step in realizing this transformation.


October 18, 2024
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Arnaldur Bragi Jakobsson

Second Wind explores the potential of reusing pre-cast concrete elements from an obsolete apartment building in Helsingborg, Skåne County, Sweden.

As part of the ReCreate initiative, which encourages the sustainable repurposing of concrete components, I collaborated with Helsingborgshem, the city’s municipal housing company, to develop a new rowhouse typology of approximately 100 m², alongside a two-story multifamily apartment building on the same plot.
The project aimed to minimize modifications to the existing structural components, preserving their original form as much as possible while adapting them to new uses. The rowhouses, arranged in an L-shape with a southwest-facing courtyard, serve as rental units and highlight the potential of reused materials in creating modern, functional spaces. The apartment buildings, located on the north and south sides of the site, further demonstrate the versatility of these repurposed elements.

 

Throughout this process, I sought to maintain a connection to the original architectural context of the Drottninghög area, respecting its mid-20th-century character while introducing new, sustainable housing solutions. This project illustrates the significant environmental benefits and creative opportunities in reusing existing building materials, paving the way for more sustainable construction practices.

 

Rowhouse plan (Arnaldur Bragi Jakobsson)


September 27, 2024
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Written by Linnea Harala & Lauri Alkki

The ReCreate pilot projects in Finland, Sweden, Germany and the Netherlands highlight diverse approaches to implementing concrete element reuse, each influenced by unique building types, contexts and organizational structures. An initial analysis by ReCreate’s business research work package (WP7) has revealed distinct patterns in these approaches, primarily categorized into centralized and decentralized models. During the ReCreate annual meeting in Zagreb, WP7 also organized a workshop to present the identified approaches to other project partners and to get feedback on the initial analysis.

 

Figure 1 & 2. Workshop between ReCreate partners at the annual meeting in Zagreb on the preliminary results of the two different approaches.

The identified approaches – A) centralized & B) decentralized

The centralized approach is characterized by a single key actor managing multiple phases of deconstruction and reuse. This model is most prominent in the Netherlands. There, the same actor is responsible for deconstructing a building and reusing most of its elements in a new structure, a process referred to as 1-on-1 reuse. The ecosystem in a centralized model is simple, with a central hub managing all operations. The key actor controls the flow of information and data mostly internally, ensuring streamlined communication and decision-making. In addition, the key actor’s business model extends to both deconstruction and reuse, highlighting its capabilities and resources. A strong single actor can oversee the entire project, facilitating optimized and controlled execution. With one key actor at the helm, there is a clearer distribution of tasks and responsibilities. On the other hand, success depends heavily on the performance and capabilities of the key actor.

Conversely, the decentralized approach involves multiple specialized actors managing different phases of deconstruction and reuse. This model is evident in Finland and Sweden, where elements are harvested and reused in various buildings. The ecosystem in the decentralized approach consists of several specialized, complementary companies and organizations. Therefore, effective communication and data sharing between these actors has been identified as a critical factor for success. In the decentralized approach, each actor operates based on its expertise and specialization, contributing to a more diversified and flexible business landscape. The feasibility of the decentralized model depends on how well the project organization coordinates multiple companies. This complexity requires robust inter-organizational collaboration to ensure smooth transitions between phases, as multiple actors require more discussion to define responsibilities at different stages, at least initially.

Overall, it can be seen that in the centralized approach, the control of the dominant key actor can streamline operations, but it relies heavily on this actor’s capabilities. On the other hand, the decentralized approach, while more complex, offers flexibility and the potential to leverage a wider range of expertise. In both approaches, the work phases and tasks are largely the same, but their overlap and sequence may vary. Ultimately, understanding these approaches allows for better strategic decisions throughout the concrete element reuse process, promoting more sustainable and efficient construction practices.


September 6, 2024
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ReCreate representatives from Sweden, Erik Stenberg and Helena Westerlind, project coordinator from Finland, Satu Huuhka, and Eetu Lehmusvaara (TAU) are preparing to exhibit the project in the Tallin Architecture Biennale 2024.

Description taken from the official website of the exhibition:

“7th Tallinn Architecture Biennale (TAB) will be titled “RESOURCES FOR A FUTURE” and curated by Anhelina L. Starkova, Kharkiv; Daniel A. Walser, Zürich; and Jaan Kuusemets, Tallinn.

TAB 2024 will be held in October – November 2024.

Architecture needs to play a key role in future change. Hereby resources are one of the main factors in the future development of our planet. TAB 2024 explores architecture and urban planning from the perspective of resources. The exhibition will focus on different parameters of resources such as building materials, typologies, orientation, and architecture to the level of urban planning and society. The exhibition will have a world-wide perspective with a local base and call for action.

After Sustainability: Architecture Remains

Escalated global tensions imposed new tasks on architecture, where architects are left with a reduced amount of resources for the creation of social mobility, diversification, and changeability as the usual parameters of conceiving architecture. What approach must we take in such a setting? The mass architecture will not disappear, but it needs to accept the resources available to it. Access to quality in architecture should not be limited to a fortunate minority. To sustain social cohesion, we have to create environmental opportunities for everyone. Architecture serves beyond aesthetic purposes; it’s a powerful transforming tool that creates social life, but for that, we have to raise the building profession by moving it into the architecture of the unseen, unpleasant and hidden.

How to conceive and construct an architectural program that remains stabilising enough to support architecture amidst ever-changing environmental conditions in perpetual crisis?

We are facing a challenge to operate within unsustainable and prevailing conditions that need to be converted into resources for the future development of society. Utilising local resources would reinforce existing structures and facilitate the transformation towards improvement and progress. Defensiveness and reusefulness will be the basis of future construction in architecture. Buildings need to be in use for a much longer time, despite our economically driven lifestyle.”

More about the exhibition here.


August 30, 2024
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Lina Brülls, Graduate Architect and Master’s Student in the Computer Science Program at Chalmers University of Technology

The master’s thesis “Resource-Driven Design” explores how the design process can be adapted to facilitate the reuse of structural concrete elements. Research done in the thesis indicates that current design and data processes are not easily translatable to reuse scenarios, where preexisting structural and geometrical attributes of materials must be considered. Based on this, three key research questions are formulated: identifying the necessary data for the reuse design process, developing a Grasshopper Rhino plugin for data integration, and applying this tool in case projects with the aim of optimising reuse.

The developed Grasshopper plugin, programmed in C#, enables data handling from Excel into Rhino. It generates structural modules from reused hollow-core and load-bearing wall elements based on desired design parameters. The tool was tested in three architectural projects on Siriusgatan in Bergsjön. Regular consultations with the ReCreate team at KTH provided helpful expertise and feedback throughout the development process.

The study’s findings suggest that integrating data early in the design process can improve the efficiency and feasibility of reusing structural elements. One key challenge encountered in this project was planning within the constraints of the generated load-bearing modules. Including glulam beams introduced necessary flexibility, enabling adjustments in level height and allowing the removal of some load-bearing wall elements.


August 20, 2024
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In this interview, we speak with Kjartan Gudmundsson, an associate professor and leader of WP3 in the ReCreate project, focusing on digital supply chain management and information sharing. WP3 is dedicated to advancing the project’s digital infrastructure, including creating digital models of individual concrete elements. Our discussion will explore how these innovations streamline supply chain processes and enhance data transparency. Join us to gain insights into the cutting-edge digital strategies driving efficiency and sustainability in construction.

Hello Kjartan and thank you for doing this interview! Can you introduce yourself and tell us about your background and role in your institution and the project?

K: My name is Kjartan Gudmundsson. I’m associate profesor at KTH in Stockholm and  I’m a leader of work package 3. I’m thrilled to be a part of the project. It’s nice to be a part of something that can promote the reuse of concrete and, eventually, building materials in general.

Can you provide an overview of the progress made in Work Package 3 (WP3) of the ReCreate project so far, and what are the key achievements in the development of data-sharing protocols and digital representations of construction elements?

K: We know how different actors (different specialists in the industry, different stakeholders and actually anyone interested) can capture and share data in a common data environment in a manner that enables other actors in the reuse process to find the information needed to support effective reuse of prefabricated concrete elements. This can support good decision-making, from the early state of doing the inventory of buildings throughout the pre-demolition audit to quality control and towards marketing or the delivery of information needed for a marketplace. This is based on knowing how to name things and how to organize data, how to integrate data and how to make an automated retrieval of the information needed in the reuse process.

We also know how digital tags can be used to track and trace the physical location of physical elements and how the tags can be used to link the physical element to its digital twin and the information linked to the digital twin.

We are in the process of taking inventory of available methods for the reconditioning of concrete elements and how to comply with health, safety, and environmental regulations.

How does WP3 contribute to the broader goals of the ReCreate project in terms of sustainability and resource efficiency?

K: Digital methods for sharing data throughout the value chain will support cooperation of different actors and support decision-making and communication with stakeholders in general and therefore facilitate sustainable and effective use of resources. Having demonstrated this in a realistic process will help illustrate it to the industry in a way that can promote further development.

The common data environment is the infrastructure making this possible while the digital tagging of the building elements makes it easier to follow the elements throughout the supply chain while the tags also make it possible to link the successively collected data to the digital model. We will also be looking at the physical processes of reconditioning the elements. Practical examples of use and full-scale testing and the involvement of industrial actors will of course strengthen the value of this contribution.

Could you explain the role of Radio Frequency Identification (RFID) technology in WP3 and how it is used to facilitate digital supply chain management and information sharing in the project?

K: We have already done a comprehensive study that shows how RFID technology as well as a number of other technologies make it possible to tag the physical elements so that we can see the location and movements of the buildings elements. One actor puts a tag on the element, the elements travel to the next place and movements are registered. Any actor with access can then read off that information.

As I said the tags can also be used to pair the building elements to their digital representatives so that the tag can be used to access a digital inventory containing information about the elements such as historical information, results from pre-demolition audit, results from quality tests and finally a material passport containing the information needed for effective reuse.

Can you share some insights into the development of a common data environment (CDE) for storing BIM data and digitized information? What challenges were encountered in creating this central repository?

K: Our work provides an overview of available solutions for Common Data Environments (CDEs) that can enable effective storing and sharing of data that is captured and created. We have also discussed how data and files can be named and stored in a manner that enables automated retrieval of files and information. The basic principle is that knowing the naming principles for files and how the data is organized in those files will give the user the possibility to search for and collect the information needed. An important feature is that we want to be able to control the access and authorisation to the different files and documents while this access can also depend on the stage of the process, from work in progress to the sharing of data across teams to published files and archived material.

This includes the use of the current platform for sharing information in the research project. We look forward to further development of digital protocols for capturing and sharing data that will support decision making throughout the reuse process, such as historical information, data from pre-demolition audit and quality assurance to give just a few examples.

Interoperability or the ability of different software to exchange data is a big issue and to some extent a challenge. In a way, there is a trade-off between using open platforms and their application programming interfaces (APIs) that allow for customisation of functionalities and the using of more well-developed software platforms.

WP3 involves creating digital models of individual elements. Could you elaborate on the process of generating these digital models, including the use of Industry Foundation Class (IFC) as an open file format?

K: The digital elements are generally created using well-known proprietary design authoring tools for 3D modelling. The main process is to create those elements with data from existing drawings. The purpose of using the IFC open file format is to make the models accessible across different software platforms. Another reason is that the IFC files have a well-defined data structure or schemas that makes them less sensitive to the software versions used. You can in fact read the files with a number of freely available IFC viewing tools and even read them with just a few lines of own computer code.

How does WP3 ensure that the information collected from the digitalization of elements is used effectively, especially in supporting the needs of designers as mentioned in WP5?

K: By having a well-defined definition of the data needed throughout the process from quality control to design we can make sure that the digital elements either have the information needed or at least a place to store that information or a link to it when it has been collected. Firstly, we have to know what is the data needed. Secondly, we have to know how to make that data accessible. So, people using different software platforms can still retrieve that data and use it for its own purposes.

Sustainable methods for stripping and cleaning elements are part of WP3’s objectives. Can you discuss the methods being developed and how they comply with health, safety, and environmental regulations?

K: This task is concerned with developing methods for cleaning and stripping deconstructed elements from old plastering, paints, tiles, wiring and wallpapers and for cutting and refurbishing components and retrofitting them for new designs. The first stage of this task is to make an inventory of currently available methods. We will also look at and evaluate different methods for cutting such as with track saws, flats slab saws or CNC robot cutting.

All the methods must comply with rules and regulations concerning health and safety in the workers environment. This includes a limit value for dust and the use and handling of solvents. This also includes methods for ventilation as well as methods for sealing off working zones. The methods must also comply with environmental regulations.

What is the significance of evaluating the cost efficiency and sustainability of the methods for cleaning, stripping, and refurbishing components? How do these methods contribute to the circular economy?

K: By evaluating the efficiency and sustainability of methods for cleaning, stripping, and refurbishing, we provide the industry with a list of available methods that can help promote reuse as a possible alternative. We would like to show how those methods comply with regulations concerning health and safety. Reconditioning is an essential part of the process. By showing how it can be done, it is more likely that people will tap into that and want to be a part of the process.

RFID-aided logistics is a crucial aspect of WP3. Could you provide examples of how RFID technology is applied in practical pilots within the project, and how it impacts the logistical processes?

K: We have already done some laboratory tests to check out how the electronic tags can be attached to the physical elements and how they might be protected as well as how factors can affect the readability of the tags. We have also been looking at different digital technologies for connecting the tags to databases and building information models.

The next step is to do some field tests of different tags to find out how they perform in different real-life scenarios in a logistic process. After that, we will be evaluating a selected number of technologies in the pilot projects of the different country clusters. The purpose of those tests is to see how well they can be used to register the travel of the elements but also how the tags can be used as the means to connect to a digital model for retrieval and uploading of relevant information.

Finally, could you highlight the key deliverables of WP3, including the common data environment, RFID-aided logistics, and the processing of deconstructed components? How will these deliverables benefit the construction and AEC industry in the long run?

K: The common data environment plays an important role in making information available to different actors and stakeholders in a reuse process. Our deliverable includes a description of the fundamental principles of making data accessible in common repositories but also on how to ensure interoperability (or how to make that data useful across different software platforms) and the benefits of using open file formats. We will illustrate those methods and principles through practical examples such as by showing how different kinds of data are stored and used to create a digital model and how that model can be populated with data from the various stages of the reuse process.

One objective of our work on RFIDs and tags is to show how the tags can be used to follow and register the location and movement of the elements. In addition to that, we will show how the tag can provide a link to digital information associated with the element. Until now, we have done quite a comprehensive literature study of the available technologies for tagging prefabricated concrete elements. In essence, this means that we have compared the functionalities of different tag technologies such as QR codes, active and passive RFIDs, NFCs and Bluetooth. This comparison includes the reading range and ability to store and retrieve data as well the possibilities to use widely available handheld instruments such as mobile phones but we have also done tests on different methods for attaching the tags to concrete and how this may affect the performance of the tags.

We want to deliver a range of applicable methods for the processing of deconstructed components. As I mentioned earlier it is important that those methods are sustainable and economically feasible but also that they can be implemented in compliance with regulations concerning health and safety.

In general, our cooperation with industrial partners and tangible examples of implementation that include full-scale testing in the pilot studies are central to the relevance and quality of our work and deliverables.

What inspired you to become involved in the ReCreate project, and can you share a bit about your personal background and interests that have shaped your role as the WP3 leader?

K: My background is in building technology or architectural engineering with some focus on how to construct buildings and how to evaluate building performance such as in terms of energy use and environmental effects. Recreate is to me a part of the transition towards more sustainable construction and with my interest in Building Information Models (BIM) and digitalization; it is very interesting to investigate how digital technologies especially can be used to facilitate the reuse process. I would like to show how it can be more effective and how can we gather information and evaluate and analyse things. Having the possibility to put the theory and methods to the test in a practical context is also a very valuable factor.

Would you like to give some conclusion to wrap up everything that WP3 does or ReCreate project is itself?

K: Great thing is to meet all the people involved and to realise what you can do with such a good team.


August 9, 2024
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Tommi Halonen, project manager, City of Tampere, Finland

Sometimes I get asked: ‘Why is the City of Tampere participating in ReCreate, and what is our role in the project?’ It might be much easier to see why a university or a construction company is taking a part in a project where the goal is to (de)construct buildings in a novel way. But what is the city doing in ReCreate, especially when the deconstruction pilot was not a public building? From my viewpoint, cities have in particular the following two roles to play in the circular transformation:

Role 1: developing public processes that enable the implementation of CE solutions.

First, cities have a significant role as regulators in the construction industry. If there are any issues related to public regulation that do not allow reuse or make it extremely bureaucratic, it is impossible or very difficult (or expensive) to create business out of ReCreate or any other circular solution. There are especially two matters that are regulated by the city authorities that are worth paying attention to: (1) implications of waste legislation and (2) product approval practices.

(1) During the ReCreate project, we’ve had multi-stakeholder discourse in Finland about whether reused building parts should be considered as waste or not – some stakeholders opposed, and some supported the waste status. However, at the end, it is the city officers that control the matter and they needed to decide how to proceed with it. I cannot go through all the matters the authorities needed to consider in order to clarify the issue but in brief, the hardest part was to find a balance between environmental protection and excessive (too heavy) bureaucracy. Eventually the authorities were able to clarify their policies so that, in Finland, reused components are not considered as waste when certain pre-requisites are fulfilled. At the time of writing this blog, we’ve also received an official decision that ReCreate elements are not considered as waste. This is a huge development step in the Finnish industry towards circularity.

(2) Another matter the cities regulate is the product approval of reused building components. Unlike new products, the CE (conformité européenne) mark does not apply to reused products. In Finland, the products are approved as part of a so called ‘building site approval process’ that is regulated by the municipal building supervisors. There is no prior experience of the approval process. Consequently, the situation is now very similar to the aforementioned case: city authorities must again develop practices and policies that ensure that essential technical requirements are met when reusing components but are not too burdensome for practitioners to comply with. As I write this blog, we are in the process of discussing these practices with the authorities.

Role 2: creating needed incentives for companies for CE development.

Cities are not only passively enabling the circular transformation, but they can – and they must – actively initiate the change, too. Indeed, me and my colleagues have received feedback from multiple companies stating that due to early stage of the circular development, the industry cannot move to circularity solely with the help of market drivers and market logic. The companies emphasized the need for public initiatives that create incentives for circular development. Cities have at their disposal policy instrument that can create this market push. The most notable instruments are (1) public procurements and (2) plot handovers.

(1) During the project, we have had multiple meetings and workshops with the leaders of the city so that Tampere could incorporate reuse to future procurements and building projects. Sooner or later, reuse of building components will break through to public procurements and when it does, it will have a significant impact on the market.

(2) Another policy instrument that can initiate change is the plot handover process. In Finland, municipalities are the biggest landowners in urban areas. Traditionally, sustainability or circularity goals have not been part of the handover processes. However, in 2022 the City of Tampere initiated an all-time first circular plot competition. It was a success with nearly 20 building proposals and applications and received a lot of positive attention in general as well as in professional media. Many cities got inspired and wanted to repeat the circular competition. What we decided to do with my colleagues was to launch a working group, the goal of which was to create upgraded and unified circular criteria for the municipalities. Around 30 experts worked on the criteria for a year, and after receiving feedback in different workshops and seminars, we were able publicize the criteria at the beginning of this year. Now, we are keen to see the impact that the criteria will create when the cities are starting to include them to their plot handovers and competitions.

All in all, while this blog is not an exhaustive list of all the role the cities have in the circular transformation, I do hope that I was able make the case that cities are one of the major players enabling the transition. Indeed, for me personally, it is very difficult to see how the industry could make the transition to the circular economy on a large scale if the cities are not developing public policies and processes to promote circularity.

 


August 2, 2024
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Lagemaat at TU/e (in collaboration with the Dutch cluster)

As part of the international @ReCreate project, we are working closely with various partners, including the Dutch cluster. This month, the Eindhoven University of Technology (TU/e) will conduct further research at our site to test concrete elements from the Prinsenhof pilot project. This research helps us understand the impact of weather conditions on the stored elements in Heerde. The materials from the Prinsenhof project will thus find a new purpose at the Circular Center in Heerde.

An important aspect of our collaboration with TU/e is testing various concrete elements for their reusability, enabling their circular application. In a recent vlog, Marcel Vullings (TNO) and Fred Mudge (TU/e student) share their findings from these tests. They investigate how concrete parts can be dismantled and what new applications are possible in future projects.

These tests are crucial for the progress towards a circular construction sector. By reusing concrete elements, we save on new raw materials and reduce tons of CO2 emissions. The collected data forms the basis for future projects.

Examples of projects that strongly focus on material reuse include the Zuiderstrandtheater in Scheveningen and the Ruijgoordweg 80 project in Amsterdam. Through this approach, we continue to innovate and contribute to a sustainable construction industry.


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Project and industry partners involved:

BTU Cottbus-Senftenberg: Prof. Dr. Angelika Mettke, Viktoria Arnold, Jakob Fischer, Christoph Henschel,
Sevgi Yanilmaz, Anton Leo Götz

IB Jähne: Peter Jähne, Milena Zollner

ECOSOIL OST: Dietmar Gottschling, Bernd Mathen, Jens Muschik, u.a.

Figure 1 – 3D Model of the test building (Source: BTU)

The objective for the test construction was to generate findings on the practicability of the construction method by reusing precast-reinforced concrete elements. The reassembly and disassembly of the test building was carried out by and in cooperation with the German ReCreate industry partner ECOSOIL. In particular, the combination of used reinforced concrete elements with timber stud walls was to be tested, as well as the new steel connectors developed as part of WP5. A new filling mortar was tested for its applicability to form the butt joints between the precast concrete elements.

Figure 2 – Donor Building Type WBS70-C before deconstruction (Source: BTU)

The donor building for the test building was a five-story WBS 70-C apartment block on Karl-Marx-Straße in the small town of Großräschen in Brandenburg. A partial demolition was carried out here as part of a refurbishment project, in which the upper 2 or 3 stories were deconstructed. From the deconstruction mass, 12 precast concrete elements were transferred to Cottbus for the test building: 3 exterior wall panels, 6 interior wall panels and 3 ceiling panels (see Fig. 3) after they had been selected and marked in the installed state.
The element-oriented deconstruction began in November 2023 and was completed at the end of February 2024. The dismantled precast reinforced concrete elements were stored on the construction site in Großräschen for another month before being transported the approx. 40 km to Cottbus in April 2024.

Figure 3 – Overview of elements needed for the test building (Source: BTU)

Figure 4 – Floor plan of the test building (Source: BTU)

When designing the test set-up, an attempt was made to reproduce as many different element connection situations as possible. These include corner connections between two concrete elements or between a concrete element and a timber stud wall (corner connector), longitudinal connections between two concrete elements (longitudinal connector) or the centred connection of a concrete wall element with a concrete element installed at right angles (T-connector) – see Fig. 5 and 6.

The newly developed connectors are made of 8 mm thick flat steel and are attached to the top of the wall elements with concrete screws. The connectors can be fixed in both concrete and wood and are therefore very suitable for combining these two building materials. The steel connectors mounted on the top can be embedded in the mortar bed required for the ceiling elements anyway, so that they do not present any structural obstacle and are also protected against the effects of fire and corrosion.

Figure 5 – 3D Models of the newly developed connectors (Source: BTU)

Figure 6 – Placement of the steel connectors in the test building (Source: BTU)

In addition, the design concept of the test building was planned in such a way that a wall element and a ceiling element were to be cut to size in order to test the effort involved in sawing the concrete and whether the cut precast concrete elements could be used as intended.

The former airfield in Cottbus, which had been decommissioned for several years, was chosen as the location for the test building. There was sufficient space, a load-bearing concrete slab as a base and a suitable access road for the delivery of the reinforced concrete elements.

In March 2024, work began on the production of the timber stud walls and the setting of the masonry calibrating layer to prepare the construction site for the installation of the concrete elements. The used concrete elements were delivered to the construction site on April 18 and 19 and stored in the immediate vicinity of the test building. They were professionally reassembled within two days. Each wall element was placed on the calibrating layer (see Fig. 7, center), leveled and secured using mounting braces (see Fig. 7). The elements were joined together using the above-mentioned flat steel connectors. The use of the innovative SysCompound joint mortar (based on fly ash and recycled aggregate) was tested for the butt joints between the concrete elements. Various formulations for the SysCompound were developed and tested in the laboratory in advance. The bond between the old concrete and the fresh joint mortar was of particular interest. In this respect, not only the mortar strength played a role, but also the shrinkage behavior of SysCompound in comparison to commercially available joint mortar mixtures.

Figure 7 – construction process of the test building (Source: BTU)

Figure 8 – construction process of the test building (Source: BTU)

The assembly of the test construction went smoothly and quickly (see Fig. 8) so a positive conclusion can be drawn for future pilot projects. The flat steel connectors have proven successful due to their simple fastening by means of screws (assembly) and disassembly; the combination of reinforced concrete and timber stud wall elements has proven to be practicable and the sawn concrete elements could be reassembled without any problems.
From a planning point of view, it is recommended that larger dimensional tolerances of the concrete elements be taken into account, as the actual geometric dimensions sometimes deviate from the planning and the edge zones of the dismantled concrete elements are no longer level in some cases. Concrete sawing work is known to be feasible but should be reduced to a minimum due to the high costs and energy required. When filling the joints, it turned out that due to unevenness or broken edges and corners of the concrete elements – as explained above – significantly more grout was required in some cases than assumed in the planning.

Figure 9 – Aerial view of the test building after completion (Source: C. Busse + S. Karas)

Overall, the test construction on the former airfield site in Cottbus was a complete success. The BTU team would like to take this opportunity to thank the landlord DLR for the space used, the skilled workers from ECOSOIL and the logistics service provider Auto Klug. Without the cooperation of the aforementioned parties, the realization of the construction project in this form would not have been possible. In mid-May 2024, the test building was dismantled/disassembled again and transported away for temporary storage at a recycling yard 42 km away. If the used concrete elements are not requested as components for reuse, they will be recycled and are therefore still available through material recycling.


June 28, 2024
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Marcel Vullings – TNO

CROW is a Dutch organisation that gather and uncloses knowledge which is relevant for civil works and buildings. CROW officially launched the CROW-CUR Guideline 4:2023 “Reuse of structural precast concrete elements” on Tuesday (11-06-2024). This guideline provides a practical description of a working method that can be used in projects involving the reuse of structural precast concrete elements. It covers various aspects, such as preparations for deconstruction, the disconnection of elements, the temporary storage of elements, the assessment of rewon elements and the reuse of these elements in new structures. The guideline has a general section that covers topics that apply to reuse of all types of precast concrete elements. In addition, it has annexes in which specific products are highlighted . Currently, there are two annexes: annex A deals with reuse of hollow-core slabs and annex B covers precast prestressed bridge girders. More types of elements are going to be added to the guideline in the near future. The guideline is for both infrastructure and buildings, in the broadest sense of the word. Many aspects are the same for both, and the non-standard aspects are dealt with in the separate annexes.

TU/e, TNO and other experts, including contractors, engineering firms, clients and testing companies, contributed their knowledge, experiences and insights to shape the guideline. In this respect, the knowledge and experiences from the pilot projects of the Horizon 2020 project ReCreate were very valuable. The wide-ranging scope of ReCreate has helped shape all the guideline’s sub-sections.

CROW launched the Guideline on site at IJmuiden. Heidelberg Materials hosted the event and after presenting a quick overview of the guideline for a mixed audience, we all got a chance to check out the temporary storage (near Heidelberg Materials) for the harvested precast concrete bridge girders. Here, the girders are waiting to be used in new bridges at various locations in the Netherlands.

Hergebruik constructieve prefab betonelementen – CROW





EU FUNDING

“This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 958200”.

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