UBC researchers have found a more reliable way to make concrete from discarded glass.
In a recent study, researchers from UBC’s Okanagan campus were able to calm a chemical reaction that has traditionally caused glass-fed concrete to weaken, expand and crack, a reaction known as concrete cancer.
“Every year, millions of tons of glass bypass recycling centres and end up in North American landfills,” says associate professor of Engineering Shahria Alam. “Like many engineers, we are interested in making smarter building materials that can give the construction industry the resources they need without necessarily having to take new resources out of the ground.”
“Researchers have been looking for a long time for ways to reliably make use of glass in concrete construction, and we believe that this research represents a significant advancement in that search.”
Concrete cancer occurs when the alkaline properties in cement paste react with silica properties that can occur in recycled concrete additives, such as glass.
In their study, Alam and co-researcher Anant Parghi, found that by adding a water-based, synthetic rubber polymer, fly ash, and silica powder to the concrete mixture, they were able to effectively neutralize negative chemical reactions.
“By partially replacing cement with polymer, fly ash and glass powder, we were able to produce concrete that was more than 60 per cent stronger than what was previously believed possible,” says Parghi. “Though further testing is needed to assess long-term stability, it now looks like we can replace up to 25 per cent of the cement materials that had to be mined for cement production with glass.”
All of the glass used in the study was taken from the landfill in Kelowna, BC and was considered waste at the time it was retrieved. The concrete additives were donated from Kelowna-based company POLYRAP Engineered Concrete Solutions.
Alam and Parghi’s study was recently published in the journal Construction and Building Materials.
UBC’s Anant Parghi (left) and Assoc. Prof. Shahria Alam hold up a piece of ‘green’ concrete and some of the glass that helped make it. Photo courtesy of UBC.