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Project recycles residual concrete

UiA contributes to developing a method to reduce waste and CO2 emissions from the concrete industry. The method will be part of the new circular economy in the construction industry.

Illustration of building
UiA joins forces with industry and SINTEF to develop a more environmentally friendly use of residues from the concrete industry.

“Globally, the concrete industry accounts for 5-7 percent of man-made CO2 emissions. We are going to test the substance Re-con Zero Evo in the residual concrete to help optimise the use and analyse the effects”, says Rein Terje Thorstensen, professor at the Department of Engineering Science at UiA.

The project name is RECONC and stands for recycled aggregate from concrete sludge with CO2-binding properties. RECONC is owned by the company MAPEI, which is a chemical supplier to the building industry. UiA is a partner in the project together with MAPEI, Ølen Betong, Velde Betong, Norcem, Schwenk Norway, the county of Agder, NORSUS – Norwegian Institute for Sustainability Research and SINTEF. The project started up this autumn and will be completed by 2024. 

Rein Terje Thorstensen er dosent ved Institutt for ingeniørvitskap på UiA.

Rein Terje Thorstensen is a professor at the Department of Engineering Science at UiA.

Financial gains

At the end of a delivery in the concrete industry, mixer trucks return to the depot. The mixer drum often contains remnants of concrete. Concrete mixing plants spend a lot of time washing out the trucks, cleaning sludge from the wastewater and neutralising it, and finally transporting residual waste to landfills. This material is of little use today. On the contrary, getting rid of it is a costly affair.

By combining residual concrete with the new substance, the goal is to make a reusable material which also has the ability to bind CO2. This will reduce waste and CO2 emissions, sludge and heavy metals.

According to Thorstensen, the term ‘waste’ is not really used anymore.

“We prefer to talk about utilising resources”, he says.

If the industry manages to utilise the residual concrete from the mixer trucks, they help save the environment while making financial gains.

“The industry will be able to save time and resources by transporting less waste to the landfill. In addition, they will have more reusable material”, says Thorstensen.

Manages subproject

UiA plays a key role in all parts of the project and has the main responsibility for subproject five, which is to disseminate the results to relevant stakeholders in industry and research.

The engineering community at UiA is particularly good at analysing the particles of sand and stone that are used in cement and concrete. They will use their expertise to optimise the recycling process of concrete sludge so that up to 90 percent of the sludge can become reusable.

The quality of the residual material is also central to the project. UiA plays a key role here, contributing with its expertise in mixing, casting and testing the service life and quality of concrete.

“It is important to produce a residual material of good quality so that it can be reused in other mixtures”, says Thorstensen.

Students contribute

The project will also be part of engineering programmes at UiA as an example of circular economy in the construction industry. UiA facilitates for the involvement of bachelor's and master's students in the research project. Students can use processes in the subprojects for tests and simulations.

“Students who participate in projects contribute to a lot of valuable research. We therefore encourage our construction engineering students to use the project and data from tests to write their bachelor's or master's theses”, says Thorstensen.