Recycled glass is the latest ingredient in the Darwin bridge construction project on Nuns’ Island in Montreal.
An estimated 70,000 recycled glass bottles were crushed into a fine power and mixed into the concrete.
According to the City of Montreal, the structure is the first of its kind in the world.
This method of construction has been used before in Montreal on city sidewalks and store floors made of concrete. But never has it been put to the test in a structure like a bridge.
“We found out the results are very good so this material performs very well in our climate,” said lead design engineer Étienne Cantin Bellemare.
The fine white prouder accounts for 10 per cent of the material used, which saves about 40,000 kilograms of cement, according to Bellemare.
Using glass powder as a replacement for cement in concrete not only makes the structure more durable and resistant, it also reduces its environmental footprint, Bellemare said.
“This is going to lead to a CO2 reduction of 40 metric tons,” Bellemare said.
He adds that projects like this will help local landfills, which have been overflowing with recycled material such as glass.
“In Quebec and around the world, we don’t know what to do with glass once it’s in the recycling bin, so now there is a good opportunity to use this material in concrete,” Bellemare said.
The pilot project was done in partnership with the SAQ and the Université de Sherbrooke.
“For more than 15 years now, the SAQ has invested in research and development aimed at finding new uses for the glass bottles it sells,” said Marie-Hélène Lagacé, vice president, public affairs.
“Using powdered recovered glass in a road bridge is an advance we find tremendously exciting.”
Construction on the eastbound lane is expected to be completed by the winter, with the bridge reopening in both directions next fall.
Bellemare says officials will be studying the structure and how it performs over the next few years.
If it performs as well as they expect, this method could be used more frequently throughout the world.