In this interview, we are speaking to Jukka Lahdensivu from Tampere University, whose work lies in WP4 in the ReCreate project. WP4 is focusing on new safety standards for reusing precast concrete components to promote sustainable construction practices. It captures the technical challenges and the practical goals of balancing safety, regulatory standards, and sustainability in the reuse of materials.
Can you explain the primary motivation behind creating a new quality management process for deconstructed precast concrete components?
Jukka: The primary motivation, in my view, is to demonstrate to customers and authorities that reclaimed components can be safely repurposed. It’s essential to ensure these elements meet safety standards when reused, and that’s why we’ve developed this process to verify their viability. We’re actively studying various aspects of these materials to ensure reliability.
How does this process differ from existing practices for virgin materials?
Jukka: There are quite a few similarities. In a factory setting, you test the raw materials, like cement and aggregates, before creating concrete and verifying it meets quality standards. However, for deconstructed materials, we’re testing the structure itself, often on-site, which is a big departure from standard practice with new materials. New components are generally tested during manufacturing, but here, the focus is on validating reclaimed components in their current state.
How challenging was it to integrate the investigation of harmful substances into the pre-deconstruction audit? What obstacles did you encounter in developing a standardized procedure for this?
Jukka: It wasn’t particularly difficult, especially since building renovations often require these studies before demolition. Finland, in particular, has a heightened awareness of harmful substances, likely because of extensive media coverage and prior issues with building materials. We’ve taken a thorough approach here, often exceeding regulatory requirements to ensure safety.
So, you would say people in Finland are more aware of these substances?
Jukka: Probably. It’s discussed frequently in the media, and we’ve faced issues in some newer buildings due to materials being enclosed prematurely. These problems have led to a deeper understanding and greater caution regarding harmful substances.
Work Package 4 focuses on ensuring reusable elements meet material and structural standards. Can you describe the testing process for these elements and their role in maintaining safety?
Jukka: We conduct tests on material properties before deconstruction to confirm the elements can be reused safely in new projects. This includes taking core samples for compression strength testing, measuring concrete cover depth over reinforcement, and conducting full-scale tests on beams and hollow-core slabs in the lab. These tests align with existing standards, ensuring consistency.
What are the key differences between assessing deconstructed versus newly manufactured components?
Jukka: With new concrete structures, we know the exact composition of materials. We need to analyse the concrete strength, reinforcement type, and other specifics for existing buildings. This lack of prior knowledge is the main difference when evaluating reused materials.
In this work package, you mention variability in material properties due to inhomogeneity. How do you manage these variations during testing?
Jukka: We conduct multiple parallel tests to gather a distribution of results. This approach is similar to testing new materials, but in a factory setting, components are consistently produced. With reclaimed materials, we often have only a few components to test, which means sample sizes differ from typical factory conditions.
Could you elaborate on potential challenges, such as deterioration, during deconstruction, transportation, or storage?
Jukka: We detected most deterioration, like cracking, in hollow-core slabs after deconstruction. These cracks weren’t visible in the building but appeared after detachment, likely due to the removal process. In Finland, we’ve also had cases where water entered hollow-core slabs, froze, and caused cracking. We had about six slabs damaged this way. When we removed the levelling on top of these slabs, accidental holes were created in the slab decks, though this was rare. In storage, however, we didn’t encounter any issues.
How do you decide on the reuse of these cracked components?
Jukka: It depends on the severity of the cracks. Small cracks with a width of 0.1-0.2 mm are often acceptable for reuse. Larger cracks, 0.3-0.5 mm or wider, need further assessment. We’ve created guidelines for visual assessment in the factory, and if significant cracking is found, a construction designer reviews it to decide on further action.
What are the most significant technical or regulatory hurdles in obtaining approval from authorities for reused components, and how might these be addressed in the future?
Jukka: The main hurdle is that authorities aren’t yet familiar with the requirements for approving reused components. We’re the first to bring this approach forward, so they’re unsure what documentation and standards to ask for. We’ve been holding meetings with local authorities in Tampere to explain our processes and the documentation we provide. This helps reassure them that we’re following a rigorous process to ensure the safety and usability of these reused components.
Best of luck with your upcoming meetings. Now, as we wrap up, what impact do you hope this work package will have on the construction industry’s approach to reuse and sustainability?
Jukka: Our goal is to develop a process that’s robust but not overly burdensome. Striking this balance is crucial to encourage widespread adoption of reused materials in construction.
Lastly, what inspired you personally to focus on sustainable construction and the reuse of materials?
Jukka: My research career has centered on the durability of structures—how they degrade and what measures can prevent damage. At our university, we’re also focused on adapting construction practices to climate change. While some researchers study climate change directly, we’re more interested in its impact on the built environment. Reusing materials is an important part of this, as it allows us to avoid new resource extraction and reduce environmental impacts, contributing to a more sustainable future.
