UBC engineering professor mixes recycled waste aggregate into concrete
Kelowna architect Hugh Bitz heard buzz about a “green concrete” project and called UBC. Bitz is always looking for ways to integrate green strategies and technologies into building projects – and decided that green concrete was the answer for constructing his own new home.
The application is based on research done by the School of Engineering at UBC’s Okanagan campus. Asst. Prof. of Engineering Shahria Alam researched methods for recycling used concrete, composite scrap, crushed and mixed as aggregate for fresh concrete. It is estimated up to 1,000 metric tonnes of composite scrap are produced in the BC Interior every year. Alam is looking for ways to keep the growing amounts of material out of landfills.
“It’s a no-brainer to see this as a positive technology that’s going to be widely used,” says Bitz, who came to know about green concrete from Okanagan Sustainability Institute Director Keith Culver.
“This is a great example of UBC’s contribution to innovation for sustainability, from Shahria’s lab bench to use in practice with a community partner,” says Culver. “This Okanagan ‘first’ shows what we try to do every day at the Okanagan Sustainability Institute, acting as a catalyst of sustainability research, development and application in the valley and beyond.”
Bitz sees an innovative future where sustainable construction practices are commonplace.
“Concrete is used in 100 per cent of construction projects for footings and foundations. It’s an easy means to reintegrate discarded materials into the building process that would otherwise go into the landfill,” says Bitz. “It just makes sense to use this in all buildings. I can see the day when every construction project in the Okanagan uses green concrete.”
Alam could not agree more.
“Aging infrastructure everywhere is being demolished and generates a lot of waste,” says Alam. It is estimated about 40 per cent of infrastructure around the world has reached its useful end of life. “The idea is why not reutilize this, instead of considering it waste.”
So Alam tested scrap concrete, crushing it into recycled concrete aggregate and mixing it in ratios of up to 100 per cent into fresh concrete. It was found that the hybrid met or exceeds the performance standard of regular concrete and is just as durable. There is the added benefit of developing a more sustainable construction industry through the recycled concrete aggregate and vastly reducing landfill waste from construction and demolition projects.
OK Builders Supplies Ltd. of Kelowna made the Okanagan Valley's first pour of concrete using recycled aggregate to form the foundation and walls in Bitz’s residential construction project. Alam will do core testing over the next two years to measure the performance qualities of the recycled concrete aggregate.
The Natural Sciences and Engineering Research Council of Canada (NSERC) is sponsoring the new-generation concrete project along with OK Builders Supplies Ltd. for three years through its Collaborative Research and Development program.
At UBC’s Vancouver campus, recycled aggregate is used for infrastructure replacement as well as new construction projects.
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