Circularity vs. Reality?

In this article, I share some of my observations and subsequent reflections on the site visits that we had last week as a part of the CIRCuIT-Circular Construction Summer School in Hamburg. Coming from an academic background, I expected to be positively surprised. Yet, the site visits exceeded my expectations and were extremely stimulating so much so that it encouraged me to write my first ever LinkedIn article and share my experience with a wider group of people who are interested in circular construction.

We had four extremely educating site visits, and for this reason, I divide this article is four sections, each ending with several open questions.

1. Demolition Site Visit

It was an interesting visit because it never occurred to my mind that cigarettes would be a big chunk of what one would find in the Construction and Demolition Waste (CDW). Nor did I know about the fact that bomb squad units need to inspect demolition sites in Hamburg before the start of the operation! This showed me how a circular process in one city requires different processes, permits and actors.

Probably, the most protruded issue that captured my attention, was a story of refusal. To begin with, the demolition contractor refused a contract from another company asking them to perform a material reclamation (e.g., bricks) for reuse instead of the demolition. They had refused the offer due to a lack of in-house expertise on how to complete this task with what actors, in how many hours, with what price, where to store the pieces before delivery and how to test their performance. Yes, even without any previous experience, their primary reason for the refusal was their disagreement on offering the deconstruction and reclamation service for the same price and within the same time limit of a typical demolition project. It was clear to the demolition company that this demand is financially unrealistic and time-wise impossible. A considerable effort would go into taking bricks out without damaging them, while further labour and procedures are needed for cleaning, undusting and protecting the bricks from any performance drop before delivery. I asked myself that if bricks are not treated as a waste to be discarded, what would be the price for reselling the bricks? Is it something that the demolition contractor should consider when offering a price for deconstruction services?

Aside from the above open questions, what truly interested me was the lack of awareness of the true costs of being involved in the circular economy. To be precise, I do not judge them for not knowing the time and costs for the service, these are rather not-established practices and there is always a first project to learn from. My question is why did the service requester think that a deconstruction and reclamation service should be (or could be) done within the same price and time constraints as a demolition service? Is it because we generally tend to think that second-hand products have lower prices than original prices? If yes, are we still treating the reclaimed materials as second-hand products or should we treat them as first-hand products? These two questions kept me thinking for the last two weeks. The only answer that I came up with is perhaps the difference in perception of what is first-hand and what is second-hand and how they are valued. Perhaps, in academia, when we talk about the reuse and reclamation of materials, we treat them as environmentally or structurally first-hand because we expect the same performance from them (in most cases). Meanwhile, the market would treat them as second-hand because they have been used once, hence, lost some value and initial costs are depreciated.

Perhaps, in academia, when we talk about the reuse and reclamation of materials, we treat them as environmentally or structurally first-hand because we expect the same performance from them (in most cases). Meanwhile, the market would treat them as second-hand because they have been used once, hence, lost some value and initial costs are depreciated.

2. Urban Planning

Never had I imagined how urban planning influences building design. The site visit to the urban planners of Hamburg opened my eyes to the importance and entanglement of urban planning and urban mining. This is because a recurrent issue expressed by several people was the lack of a storage place for reclaimed materials, whether on-site or off-site. Exacerbated by the fact that it might take some time for a reclaimed construction product to find a user, there is so far no solution. Land prices are expensive and not cost-effective for actors to just store some “might reusable” products for a long time. Well, this issue and the urban planning site visit made me think if the government or city should also provide a local storage site in every urban area. We are not foreign to the idea of having recycling centers, so why not a storage place? Maybe not in already built urban areas or historic city centers, but should they start some initiatives? After all, city planners seemed to be concerned with social housing, so can they provide a similar place for social circular storage? (I just invented the name :) )

After all, city planners seemed to be concerned with social housing, so can they provide a similar space for social circular storage?

If we are going to redesign the whole way of engineering, architecture and procurement in circular construction, perhaps it is time for other actors to step up and provide some lands owned by the city for circularity. If lack of a storage place is repeatedly stated as one of the primary barriers to circular construction, should we not expect to try to integrate it into our urban planning?

3. Design with Reusable Structural Elements

The third interesting visit was to a co-op that intends to build a multi-functional social housing in place of a decommissioned multi-storey parking. They had intended to reuse the lower parts of the structure of parking, cut some openings in the middle for lighting and build on top of the slab of the first floor. I was curious to know how they concluded that they could reuse this slab of the first floor and build modules on top of it. As a non-structural engineer, I was literally dying to know the answer. The answer, surprisingly, was through a pre-demolition audit. I was secretly a little bit disappointed as I expected them to name some innovative assessment methods and procedures. Well, that was not all! They went on and explained that chloride has infiltrated the concrete slabs and columns which renders them unsuitable for structural reuse. My initial disappointment slowly turned into shock. They have finalised the architectural plans and had spent hundreds of thousands of Euros on this project so far. How could the pre-demolition auditors have missed that the exposed concrete parts in a port city would not need chemical tests?

Not only they cannot use the slab anymore, but they have to demolish the whole building. This means they need to secure extra funding. The first question that popped up in my mind was: Are we too enchanted with the promises of circularity and reuse in construction? How can we calibrate our expectations?

Are we too enchanted with the promises of circularity and reuse in construction? How can we calibrate our expectations?

Remembering this quote from Thomas Edison “I have not failed, I have just found 1000 ways that won’t work,” dissolved my initial shock and I started to ask better questions. How can we use this experience as a first steppingstone for creating a proper pre-reuse assessment strategy for buildings? Should they have treated the structure as a new piece of concrete and evaluated it with available and mandatory tests? Are there parameters that would definitely need practical tests and others that would need visual inspection only?

But the story does not end here! The project leader made a remark that intrigued me. They expressed that was concrete slabs were directly exposed to air for over 60 years. Had there been maybe a protective layer, the chloride intrusion could have been prevented. Although I cannot affirm this, I know one thing. In the Design for Deconstruction (DfD) guidelines, it is advised to avoid adding extra layers in order to make the elements more usable for the future. However, in this case, the situation seemed to be the opposite. Protection could have potentially saved the concrete. Should we re-think the power of protective layers against exposure instead of completely neglecting them for the sake of future reuse? Could not having protective exterior layers backfire on us in a future where we expect more extreme climate events, higher temperatures, pollution, and acid rains? My conclusion was that perhaps more effort should be directed toward creating sustainable protective layers instead of completely removing them from the equation. Overall, this social housing was an extremely stimulating experience for me because it showed me what types of problems can we expect from the existing urban area.

4. Concrete Made With Recycled Concrete Aggregates

On the last day of the visit, we visited “Die MusterBude,” a beautiful demonstrator of how recycled concrete and other construction products can be used in future buildings. Not only had they used different recycled materials in their pilot project, but they have also used them in different structural elements to test the performance of this new concrete with conventional cast-in-place concrete. What I learned from them was:

• Cement has the most environmental impact the concrete which is something that cannot be recycled.?We can crash the concrete and reuse it, which is called downcycling, but we cannot obtain cement again from concrete. There have been some efforts on making alternatives or at least additives that enable the same structural performance but nothing on a large scale.
• Recycled concrete aggregates are usually rough. Therefore, its interaction, physically, is different from natural aggregates. Likewise, its chemical interaction is also different from that of natural aggregates because it has already been once active.
• The performance of the concrete made with recycled concrete or brick is not equal to that of conventional concrete. Therefore, their use cases are so far limited to walls, pavements, and so on. We cannot use it for the foundation.
• Despite the increasing demand for recycled concrete aggregates, the price is high and the amount is low. But this demand is not necessarily for using recycled aggregates in new concrete. On the contrary, because the new concrete made with recycled aggregates does not meet the standards, there is no demand for this application. Rather, the demand is mostly for using concrete in applications with a lower need for load bearing.
• Construction and demolition wastes are not properly sorted, which leads to lots of impurities in the resulting aggregates.
• Easy access to natural resources could be an anti-driver for using recycled aggregates. As long as raw materials, e.g., sand and gravel, are easily attainable, the momentum for creating robust concrete with recycled concrete aggregates will not increase.
• And my most valuable lesson: the dilemma of fly ashes. Fly ashes are good replacements for cement (nor completely). Therefore, adding them to the concrete mix can reduce the environmental impacts of concrete. At the same time, fly ashes are by-products of coal-burnt power plants. However, if we stop these power plants because of their negative ecological footprint, then we will not have access to fly ashes anymore. Quite a trade-off if you ask me. I am not an expert in this field, but I found this issue particularly interesting.

Disclaimer: As this piece is a personal reflection on the site visits, it does not necessarily reflect the opinions of the people that I met during this experience.?

Final words: I would like to thank CIRCuIT-Circular Construction team for organising these site visits and truly propelling the circular construction in academia and practice.