Recycled concrete becomes new concrete

In the research project called RE:Concrete, Madumita Sadagopan will recycle concrete waste into new concrete, which can then be used for load bearing elements in the structural framework of buildings.

"We see that there are great environmental benefits in recycling concrete. Instead of using gravel or crushed rock as aggregates in concrete, we can reuse the concrete waste as aggregates in the new concrete, reducing thus the negative impact on the ecosystem. In addition to such environmental benefits, even the technical lifetime of the concrete is extended", says Madumita Sadagopan.

"Today, concrete waste is used as a filling material in landfills and in roads. I want to show that there are more high-quality applications, such as its use in load bearing concrete elements in building structures."

Such concrete waste can be sourced from demolition sites, or from production rejects and spills from the concrete production industry.

The concrete lab at the University of Borås is divided into two areas. One for aggregates and the recycling of concrete and one for concrete technology. The lab, which was completed in autumn 2017, has lead the way for the powerful development of research related to Concrete technology at the University of Borås. The lab is funded by Gunnar Ivarsons stiftelse and the University of Borås, and is an effort to expand the research in the discipline of construction technology.

"At the moment we use waste from one of AB Bostäder's properties. We also study how Ulricehamns Betong AB (UBAB) and Hedareds Sand och Betong AB can reuse their own waste and make new concrete."

Unique research

The five year project is a collaboration between the University of Borås and CBI Betonginstitutet, RISE. The project includes a reference group with local and national companies such as NCC Recycling, UBAB and Hedared Sand och Betong.

"During the 1980s, a lot of research was carried out in the recycling of concrete in Sweden. However, it is only in recent years that recycling have come back into focus, while Sweden's environmental objectives for sustainable development have begun to apply."

Madumita Sadagopan has majored in construction engineering and has acquired her Master's Degree in Resource Recovery at the University of Borås. After her master’s studies she began her PhD education with the research project RE:Concrete.

The project takes on the task of replacing all the aggregates in the new concrete with crushed recycled concrete. As of now, these recycled aggregates are tested in three different concrete recipes to verify if the compressive strength of the new concrete equals that of the old parent concrete. Tests are conducted in the university's concrete lab and at the CBI Betonginstitutet.

“Among other things we test, the properties of the crushed concrete such as water absorption and particle size distribution. The intention is to be able to characterize the crushed concrete as suitable aggregates for new concrete securing thus good compressive strength and workability. However, there is also another aspect that we want to look into, namely the logistics and market potential for the recycled concrete aggregates. Which is why we have started a collaboration with the departments of Industrial Economics and Logistics here at the university."

“Two groups of students from the Construction Engineering programme are linked to the project. They will carry out their bachelor’s degree projects with focus on characterization of recycled concrete aggregates and the proportioning of concrete with recycled concrete aggregates", says Madumita Sadagopan.

The project is funded by Gunnar Ivarssons stiftelse, RISE and the University of Borås.

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More about the project

Madumita Sadagopan

Text: Annie Klasén
Foto: Suss Wilén
Translation: Suss Wilén