concrete construction

Recycled concrete performs as well as conventional concrete, study confirms

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A five-year University of British Columbia study has concluded that recycled concrete can perform as well as – and in some cases better than – conventional concrete.

Waste materials from construction and demolition contribute up to 40 per cent of the world’s total waste. Concrete waste is the most prominent waste generated by the construction industry, mainly being disposed of in landfills.

Recycling this waste in the form of recycled concrete aggregates – bonded together with an adhesive paste – and substituting it for natural aggregates in the production of fresh concrete could assist environmental conservation efforts. However, intense use of recycled concrete in industrial production of new concrete is not widely accepted due to its high porosity, a disparity of source concrete and a lack of field studies.

Researchers from the University of British Columbia’s school of engineering conducted side-by-side full-scale comparisons of recycled and conventional concrete within two common applications: a building foundation and a municipal pavement.

“We live in a world where we are constantly in search of sustainable solutions that remove waste from our landfills,” said Dr Shahria Alam, who led 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.”

The researchers tested the compressive strength and durability of the recycled concrete compared with the conventional concrete. They found that the long-term performance of recycled concrete adequately compared to its conventional form, experiencing no issues over the course of the five-year study.

The recycled concrete was found to have a higher rate of compressive strength after 28 days of curing, while maintaining a greater or equal strength throughout the period of research. The study’s results suggest that recycled concrete can be a 100 per cent substitute for non-structural applications.

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

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

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