Future cities could be 3D printed — and greener
How recycled materials innovation can build sustainable cities
Building better
We used brown soda-lime beverage glass obtained from a local recycling company. The glass bottles were first crushed using a crushing machine and then the crushed pieces were washed, dried, milled, and sieved. The resulting particles were smaller than a millimeter square.
The crushed glass was then used to make concrete in the same way that sand would be. We used this concrete to 3D print wall elements and prefabricated building blocks that could be fitted together to make a whole building.
The presence of glass does not only solve the problem of waste but also contributes to the development of a concretewith superior properties than that containing natural sand.If used in this way, waste glass can find a new life as part of construction material.
The thermal conductivity of soda-lime glass – the most common type of glass, which you find in windows and bottles – is more than three times lower than that of quartz aggregate, which is used extensively in concrete. This means that concrete containing recycled glass has better insulation properties. They could substantially decrease the costs required for cooling or heating during summer or winter.
Improving sustainability
We also made other changes to the concrete mixture in order to make it more sustainable as a building material, including replacing some of the Portland cement with limestone powder.
Portland cement is a key component of concrete, used to bind the other ingredients together into a mix that will harden. However, the production of ordinary Portland cement leads to the release of significant amounts of carbon dioxide as well asother greenhouse gases. The cement production industry accounts for around 8% ofall carbon dioxideemissions in the environment.
Limestone is less hazardous and hasless environmental impactduring its production process than Portland cement. It can be used instead of ordinary Portland cement in concrete for 3D printingwithout a reduction in the qualityof the printing mixture.
We also added lightweight fillers, made from tiny hollow thermoplastic spheres, to reduce the density of the concrete. This changed the thermal conductivity of the concrete,reducing it by up to 40%when compared with other concrete used for 3D printing. This further improved the insulation properties of the concrete, and reduced the amount of raw material required.
Using 3D printing technology, we can simply develop a wall structure on a computer, convert it to simple code and send it to a 3D printer to be constructed. 3D printers can operate 24 hours a day, decrease the amount of waste produced, as well as increase the safety of construction workers.
Our research shows that an ultra-lightweight, well-insulated 3D building is possible – something that could be a vital step on our mission towards net zero.
Article bySeyed Ghaffar, Associate Professor in Civil Engineering and Environmental Materials, Brunel University London,Mehdi Chougan, Marie Skłodowska-Curie Research Fellow, Brunel University London, andPawel SikoraAssociate professor in Civil and Environmental Engineering, West Pomeranian University of Technology in Szczecin.
This article is republished fromThe Conversationunder a Creative Commons license. Read theoriginal article.
Header image:Peri
Story byThe Conversation
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