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AU installs giant concrete mixer for sustainable construction

In the building laboratory at Aarhus University, researchers and students are mixing concrete for more sustainable construction.

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The university's new concrete mixer is highly automatic and it can dose very accurately the desired amount of cement and water. In this way, researchers can avoid material waste and thereby reduce the climate footprint of a building. (Photo: Nicolai Hildebrand)
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Annette Beedholm Rasmussen is working on concrete supporting structures at Aarhus University. (Photo: Nicolai Hildebrand)

Concrete is the most widely used building material in Denmark and globally, and it accounts for a large part of the overall climate footprint of the construction sector. For this reason, any new solutions the engineers come up with to reduce material consumption will never be small fry.

The cement content of concrete is particularly important for the climate footprint, and Aarhus University has now invested in a mixer that will make it possible to reduce the amount of material used, and there’s huge potential, says Annette Beedholm Rasmussen, associate professor and head of section at the Department of Civil and Architectural Engineering at Aarhus University:

"This gives us an opportunity to experiment with different mixing ratios of cement and water in the concrete and to carry out static tests of the elements in our laboratory. The aim is to generate new knowledge to form the basis of a construction practice in which we can differentiate the cement content much more. Overall, it could reduce the CO2 accounts for construction significantly."

Today, when concrete is delivered to a building site, in the vast majority of cases it will have been premixed at a factory and on a truck, with a high concentration of cement.

"They have to choose one strength for the whole mixture for all the construction elements, even though such strong elements are only required in a single place," says Annette Beedholm Rasmussen.

A comprehensive experiment

Annette Beedholm Rasmussen is working with reuse of concrete elements, and she will use the smart mixer to conduct experiments with new types of concrete casting at Aarhus University.
Her idea is to vary the strength of the material according to how it will be used.

"With the new mixer, we can very accurately dose the amount of cement on site. This means, for example, that we can mix concrete with a high strength and thus a lot of cement for the foundations and the lower floors of a building, and another kind of concrete, with smaller cement concentration, for the upper floors, which don’t have to carry as much weight," she says.

In collaboration with Fibo Intercon, the company behind the concrete mixer, Anette Beedholm Rasmussen is also considering experimenting with mixing cement with new materials such as foam, algae and hemp.

"It's a very interesting and relatively unexplored area, but we now have an opportunity to take the experiments into our research labs, where we can document the static properties of the elements we cast. It’s an important step towards more sustainable construction with concrete," she says.


Annette Beedholm Rasmussen, Associate Professor, Head of section