A five-year study has found that recycled concrete performs as well, and sometimes better, than conventional concrete.
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.
What UBC has been doing these past 7 years is use the aged recycled concrete aggregate mix, which has attained a stronger affinity to further aging, compressive and tensile strength.
The renewed formulation is much like the ancient Roman cement/concretes which have pozzolanic materials in them.
This can be reproduced in regular mixes of today by blending the recycled concretes/types of cement with crushed FlyAsh/Steel slags/droses with certain Pozzolanic Zeolites.
This reduces the % of Portland cement needed by up to 70%, increases the corrosion resistance and the overall cured strength, and is lighter.
Has been done by numerous Universities over the past 15 years on an experimental basis.
By reducing the % of Portland cement the GHG’s are reduced per batch by more than 50+% and thus a cost-savings overall and allows more production for the same cost of an original formulated Concrete an is “Greener.”