Cement made from brine waste

by Ofentse Sefolo
Cement made from brine waste

This year’s Venice Architecture Biennale has delivered a number of thought provoking and uniquely innovative exhibitions showcasing the best in product development and the future of architecture.

One such innovation is a large-scale prototype created from an environmentally-friendly cement made from recycled industrial waste brine. Presented by the United Arab Emirates (UAE) and curated by Wael Al Awar and Kenichi Teramoto, the exhibition showcases an exciting research project where they explore how the salt and mineral compounds found in the UAE’s sabkha (salt flats) could act in the development of renewable building materials.

Salt-based protype

This project holds significant benefits as Portland cement accounts for 36% of all emissions related to construction activities and 8% of total anthropogenic CO2 emissions globally.

Named the Wetland, the project displays a salt-based prototype measuring 2.7 metres tall and 7 metres by 5 metres wide on its exterior, creating a walkable interior space the size of an average 2x5mx5m room.

Formed by using 3000 modules made from a MgO-based cement designed by the curators in a collaborative process, the sustainable alternative to concrete by the UAE offers much food for thought. One of the curators, Wael Al Awar, shares their vision with the research project and its intent to contribute to the climate change urgency.

Q: Where did you start looking for alternatives to this binding material?
WAA: We started looking at the local geography, trying to see what could work as a glue other than lime. We stumbled upon the salt flats of the UAE and were fascinated by the crystal layers that formed when the salt crystallises. It becomes strong, meaning that there is a binder.

Once we started investigating further, we understood and learned, for example, that Siwa, which is in Egypt is totally built from Karshif, a mix between salt and mud, a part of their vernacular architecture. We also learned that that the binding material or glue is the mineral magnesium oxide (MgO).

Q: Where can you source the glue?
WAA: We discovered that the best place in which to source MgO is the reject block drying from desalination water. We extracted the MgO from the desalination water process and used it to create this cement.

The cement blocks you see here are all produced locally in Venice. Instead of creating CO2 emissions, this cement we have created needs to absorb CO2 to gain a structural strength to dry.

Q: How did you decide the form of the building blocks?
The building blocks can be made into bricks or slabs. However, now that we have questioned cement, we had to question the modern process of producing architecture too. We needed to question standardisation and globalisation, because modern architecture faces tremendous challenges against cultural identity. How do you keep culture or retain it in architecture?

Vernacular architecture is produced from materials found in nature – you find wood, you work wood. There is a certain connection between the architect or the builder and the material. I think in modern architecture that this is completely lost. The architect and the material have become so distant from one another that I can draw a design, send it anywhere in the world and have it built without having to go there. However, we need to question that process to see if it is the right way moving forward.

We were inspired by the vernacular architecture of the UAE which is made from coral. We drew coral shapes into sand moulds and cast them with concrete. These shapes were drawn by the builders themselves. We decided on four different types with two different sizes each, so eight modules in total. This was just for efficiency, speed and scale. It can be done in many more modules and types.

This approach is the antithesis of modern architecture. There is no drawing for this product. We have a guideline for the contractor and our process method, but we don’t have an architectural drawing with precise dimensions. We have a guidebook, meaning that each culture can introduce their own identity or understanding into that guidebook. The production of this material anywhere in the world will always look different. The building block we have here in Venice looks random and chaotic but actually, it’s scientifically well studied.

Q: What is the current state of the project?
WAA: This is three years’ worth of research, but there’s still has a lot of research to be done. We are only able to produce the blocks as precast units because they still need carbonation. This is because a cast in-situ system is extremely hard to carbonate. Then you have the challenge of reinforcement. You cannot reinforce with steel, because it’s assault-based concrete. More research development is needed to find other ways to reinforce it. We could possibly introduce the CO2 molecule in the cast in-situ process chemically to give it that enforcement.

Our sincere thanks and appreciation to Venice Biennale for the information contained in this article.

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