BioConcrete Collection Of Tiles Made From Invasive Species

Collection en Route, of concrete-like tiles made using Japanese knotweed and shells from American signal crayfish.

Images © Brigitte Kock and Irene Roca Moracia

Brigitte Kock and Irene Roca Moracia, graduates of Central Saint Martins, have designed bio-concrete using Japanese knotweed and shells from American signal crayfish. These non-native species have been causing ecological and economic damage in the UK.

Could you tell us about the development process? The initial product you made and how it was further developed?

We started looking into how incorporate the by-products originated from the removal of the two invasive species into the creation process of an architectural material. We started off by making many different samples of 10x10cm, trying different methods like, making glass, creating stone through compression and water bathing. In the end the samples using ancient roman concrete techniques worked best, so we continued to make the collection with that method. This product is still on the early stages of testing and development. We’re now deciding when and how continue with the production of Collection En Route.

Which areas do you feel bio-concrete could be extremely beneficial at?

In luxurious interiors it would be great if this could replace less sustainable/regenerative materials, like concrete or limestone. The fact of having an alternative to the current unsustainable Portland cement can change completely the environmental impact that construction has. A bio concrete like this one could be used for any kind of finish at the beginning without compromising structural elements until it is properly tested and controlled. But it could be used for anything because we are able to cast it into anything – from tiles to furniture.

What other possible applications do you see for the material?

Since it can be poured into any shape we would like to try to use the material to create furniture. We would like to experiment with the shapes and thicknesses to understand how the material can work best and furniture is a great field to that without compromising in safety or structural issues

“Sustainability is the realm of ‘can’t, shouldn’t, mustn’t’, where ecological gains are at the cost of economic gains, this prohibiting narrative does not inspire most of us.”

Please could you explain why was it important to you for the project to be not just sustainable but regenerative?

Sustainability is the realm of ‘can’t, shouldn’t, mustn’t’, where ecological gains are at the cost of economic gains, this prohibiting narrative does not inspire most of us.

Regenerative design takes a step further and is about creatively thinking of creating a positive impact on the nature around us. And in doing so, it shows that economic and ecological gain don’t have to be mutually exclusive. Sustainability will help humanity survive, regenerative design will help us thrive.

So, since the beginning of the project we felt needed to do something more than just a sustainable product, we wanted to create a positive impact — a regenerative material. We live in a moment when there is no time to question if something should be or not sustainable, I think our generation understands the need for a sustainable future.

However, both of us think this is not enough if we really want to create a change. We approached our research on how to incorporate a bio product (the waste of those control industries) that we, as a society, are forced to produce if we want to assure and protect the future of our local biodiversity.

We do not see this project like a waste-based product. This waste is not coming from a human luxury industry (like plastics) but from a necessity to protect (and beyond that regenerate) our natural environment. We need those industries to control the damage we have already caused. And rather than leaving them into the “dangerous” classified rubbish category they have now, we wanted to integrated them into a production process so that it creates economic as well as ecological gain.

Lastly, with Collection En Route, we wanted to showcase the absurdity of the situation with the classification and disposal rules here in the UK that do not allow to do anything with those two species after being treated and put into bags while you can perfectly order those by-products online and import them from China for example.

We’re excited that this project might bring ‘regenerative design’ from architecture (where it is mainly practised) into product design and inspire more creatives to start thinking about the bigger, positive impact that a design can have.

To what extent are these production processes scalable?

The product can be scaled up in size really easy but the production will always be related to the quantities the control industry is capable of obtain and treat. We need to clarify that in the case of the crayfish for example there is maximum allowed per area and day so our product will have to adapt to the sustainable fishing that is being done. We do not want to create a new industry around this product but to relocate the waste that the one operating is producing. We do not want people to cultivate this plant or animal to produce the bio products because this will be a bigger problem.

Also the problem here is not if we can scale up the product or the production process, because that could be easily done like with concrete, but if construction rules will develop themselves rapidly to allow us to use those products in the construction industry. Nowadays it is really difficult to use some of the already existing bio concretes, some of them base on volcanic ash as binder, because the codes and construction rules don’t allow it yet. That is way our product would work perfectly as a finish or interior material in the foreseeable future and not as a structural concrete.

Have you done tests for durability etc. and how this compares to traditional stone/concrete. If yes, what were the findings?

At this stage of the project (research) we haven’t been able to test it as a structural material, the main intention of the product is to be a finishing. Although we are sure that with the proper standardisation and tests we could achieve a product that could be used for any type of place as concrete does.

How does the material get stronger with time?

Through the curing process. Curing plays an important role on strength development and durability. The chemical reaction between the binder and water allows to continue to its maximum level. We achieve that controlling the humidity and the percentage of water. This process does not stop after mixing but it continues on time.

How is the American Signal Crayfish killed removed from the environment? Is it used in the gastronomy industry or anything like that?

Crayfish can be removed by via mechanical methods: trapping, seining, and electrofishing. This method can control the population, but not eradicate it. Another more effective eradication method is chemical. However, since the crayfish are being eaten by predators (fish & birds), the chemicals in the crayfish will bioaccumulate through the food-chain, which is very undesirable. So, often, the choice is to catch the crayfish manually, because this is cheapest and most effective method to manage their population without harming the rest of the local biodiversity. Additionally our expert, Bob from Crayaway, told us that the laws have changed since December 2019. So now all the crayfish he catches around the UK is only allowed to be sold dead/frozen. Which means that all the local restaurants that bought from him before this law, are not interested in buying anymore, because frozen crayfish is not fresh.

As Bob puts it on his website: “The UK annually imports over 1,000 tonnes of cheap Chinese crayfish tail-meat (7,000 tonnes of trapped crayfish). The Chinese export the Red Swamp crayfish which is known ‘to be the hardier of crayfish species, able to tolerate polluted water’. The species that do quite well in China’s polluted waters might be wild and sustainable, but would you want to eat them? China itself is looking for a supply from the UK, which clarifies how they think of their own crayfish. The import of crayfish is an unnecessary carbon-footprint, especially while there is a far superior product in the UK, a product that needs to be removed. Entrepreneurs and volunteer groups are trying to encourage eating the invasive UK populations.”

How many different finishes can you create using these two materials?

We researched different processes and materials in parallel to the bio concrete. We are certain that the different by-products that we can obtain from the control industries could be incorporated into different production methods. They could be used as natural pigmentation or even reduce the firing temperature for ceramics and glass. They’re so many possibilities and we managed to explore only a concentrated part of those.

For our bio concrete we can obtain a raw felling really close to concrete itself or to a rock. depending on the porosity we achieve. It can be sanded and sealed as concrete. And the colours can be really diverse depending on the percentages and the curing times.

How do you source the materials from the removal companies even though this is technically illegal and in what condition do you receive them?

All the materials we use have been treated naturally and no chemicals were applied to them. This means we only use those that were controlled manually. In the case of the Japanese knotweed they are forced to burn the roots and then seal it in a bad for disposal, this is how we obtain the wood ash. Sometimes it is easier because it is just the upper part of the plant that has been let to dry after cutting it.

It is forbidden to collect or handle the Japanese Knotweed in the UK, It is not illegal for you to have Japanese knotweed on your property, but it is against UK law to cause or allow the plant to spread in the wild.

So, it is legal to have Japanese Knotweed on your property, but you can be prosecuted or given a community protection notice for causing a nuisance if you allow it to spread onto anyone else’s property. That is why you can’t touch this plant if you do not have a control license. And after they dispose it in their bags it becomes dangerous waste and you can’t use it. The signal crayfish was always given to us after few days frozen. We have ran the project under research principles. We always explained the purposed of our project and what we were doing with it. That is why certain removal companies accepted to give us a certain amount and even to bring us into the field to see the collection process with them. But we must remark that this is extremely complicated to obtain. Even scientist working with those two species have problems to get their hands onto them.

Why/how are Japanese knotweed and American signal crayfish causing the biggest damage to the UK?

Philipp Franz Balthasar von Siebold (17 February 1796 – 18 October 1866) was a German physician, botanist, and traveller. He achieved prominence with his studies of Japanese flora and fauna and the introduction of Western medicine in Japan in the late 1840’s. Philipp brought the plant to the UK. Here he found a steady clientele of customers from both botanical gardens and the high society who thought this plant with its lovely bloom and odd shaped leaves was the height of fashion. What started as an ornamental plant in gardens, is now abundant in the wild: as we know, fashions come and fashions go, and by the time the fashion went there was no stopping the invasive species spreading throughout the UK. The plant is known to have a negative impact on local biodiversity, flood risk and ecosystem services. Significant risk to the structural integrity of constructions. With the ability to grow through walls, tarmac and concrete, it can wreck roads and buildings. It is capable of devaluating a property completely if it is found in the plot. It is regarded as a pest in many parts of the country because of its quick growth, which allows it to dominate habitats and exclude other plants. In Japan, the plant is held in check by natural enemies (invertebrates (insects) and fungi), but these enemies are not naturally found in the UK. The problem is now so great the government estimates that controlling the weed countrywide would cost £1.56 billion. Methods to eradicate the weed:

Physical: Most public spaces and government plans are just population control. (cutting stems and grazing by cattle)

Chemical: Aggressive pesticides ( sprayed repeatedly, really expensive) Biological: Biocontrol programme ( insect and a fungal disease )

Crayfish-loving Sweden had begun to suffer losses of their native crayfish and in 1970 started importing the American Signal crayfish which were known to be immune to the plague. It was not understood that American crayfish were, nonetheless, potential carriers. This soon became apparent, however it had already been introduced in the UK as a lucrative market to supply the Swedish. More countries had this plan and soon the prices decreased, resulting in an abundance of crayfish with countries like China being able to offer low prices. The abandonment of the expensive UK fisheries caused many crayfish to escape into the wild.

Introduction severely impacts local plant and animal biodiversity, and alter water quality and sediment. Its burrowing activity increases risk of damage to dams, dykes, irrigation networks and riverbanks, causing floods and bank failure and sometimes that causes bringing down buildings and infrastructure. For example, the burrowing into earth dams at Prior Park Landscape Gardens in Bath has necessitated repairs costing around 2.2 million pounds.

Are there plans to actually use the material in LVMH brand stores? How far in the future would this be?

The project was developed for the LVMH 2020 Climate Week and it was presented to the different Maisons in December in Paris. Project Brief: LVMH and Maison/0 would like to work with graduates of Central Saint Martins (CSM) to research and develop innovative, new materials for the built environment that can be showcased by LVMH at an upcoming event in November. Sustainability should be considered and embedded throughout the project.

Our project is still in the early stages. We had prototyped different variations of the bio concrete but we still need to test the material more. To find a standardised product will probably entail years of work.

How does your recipe differ from the wood ash cement originally developed by the Romans?

There is no clear recipe that has survived over time but a principle with certain variations according to the use or location of the roman structures built. At present, there is no way of ascertaining what water/cement ratios the Romans used. Romans used volcanic ash or wood ash as binder in their concrete constructions and their aggregates tended to be much bigger than what we normally use now, they added broken bricks and rocks to the mix.

We have followed their principles and created a bio concrete with different recipes variations. We have played with the ratios to obtain really strong results. The final colour and textures depend on curing times and aggregates chemical reactions with the binder and the water. This part is really close to what romans did — they knew how to incorporate different elements to the curing process to obtain different results, for example concrete structures that can resist to the corrosion caused by sea water. We have submerged roman constructions that have survived to our times. Our modern concrete can’t perform at that level, it deteriorates rapidly in saltwater and over time. Just like the aggregate, our binders have an organic origin, as much of the sands and rocks the romans used or modern cement, we can’t forget that limestone often contains fossils. So, our bio cement is our own interpretation of what we could achieve following the roman principles of concrete production.

While sustainable solutions have been increasing in popularity, utilizing otherwise purposeless, or as in this case, invasive substances, to create something that can be used beneficially and eco-consciously, like the Collection en Route project is rare, yet much needed.

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