Recycled concrete holds up in structural applications

A five-year study has found that recycled concrete performs as well, and sometimes better, than conventional concrete. 

recycled concrete
Shahria Alam, co-director of UBC’s Green Construction Research and Training Centre and the lead investigator of the study (Image: UBC Okanagan)

Researchers at the University of British Columbia’s Okanagan’s School of Engineering compared the compressive strength and durability of recycled and conventional concrete within a building foundation and a municipal pavement. They found that the recycled concrete had comparable strength and durability after five years of being in service.

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“We live in a world where we are constantly in search of sustainable solutions that remove waste from our landfills,” said Shahria Alam, co-director of UBC’s Green Construction Research and Training Centre and the lead investigator of the study. “A number of countries around the world have already standardised the use of recycled concrete in structural applications, and we hope our findings will help Canada follow suit.”

According to Alam, waste materials from construction and demolition contribute up to 40 per cent of the world’s waste and in Canada that waste amounts to nine million tonnes per year.

Concrete is typically composed of fine or coarse aggregate that is bonded together with an adhesive paste, whereas recycled concrete replaces the natural aggregate.

“The composition of the recycled concrete gives that product additional flexibility and adaptability,” Alam said in a statement. “Typically, recycled concrete can be used in retaining walls, roads and sidewalks, but we are seeing a shift towards its increased use in structures.”

According to UBC, the researchers found that the long-term performance of reused concrete adequately compared to its conventional form and experienced no issues over the five years of the study. The study found that reprocessed concrete had a higher rate of compressive strength after 28 days of curing while maintaining a greater or equal strength during the period of the research.

The researchers suggest the recovered concrete can be a 100 per cent substitute for non-structural applications.

“As innovations continue in the composition of recycled concrete, we can envision a time in the future where recycle concrete can be a substitute within more structural applications as well.”

The team’s findings have been published in Construction and Building Materials.