Recycled concrete could reduce pressure on landfills

The findings, published Monday in the journal Construction and Building Materials, could help keep rubble out the landfill.

For the study, engineers poured recycled cement to lay a building's foundation and a pave a municipal sidewalk. Researchers kept tabs on the material structures over a five year period.

Both the foundation and sidewalk proved as strong and durable as similar structures built using traditional cement.

"We live in a world where we are constantly in search of sustainable solutions that remove waste from our landfills," lead researcher Shahria Alam said in a news release.

"A number of countries around the world have already standardized the use of recycled concrete in structural applications, and we hope our findings will help Canada follow suit," said Alam, co-director of the University of British Columbia's Green Construction Research and Training Center.

According to a Alam, refuse from construction and demolition accounts for 40 percent of the world's waste. Recycling rubble into concrete could alleviate the burden of demolition and construction activities on landfill.

In addition to filling up landfills, the creation of concrete contributes to carbon emissions. However, some studies have shown concrete acts as a carbon sink once poured.

To make concrete, a fine or coarse aggregate, usually made up of sand and small rocks, is mixed with water and cement paste. To make a more sustainable material, researchers replaced natural aggregate with rubble from demolished concrete.

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

Researchers found the strength and durability of the building foundation made using recycled concrete was equal to that of a foundation built with traditional concrete.

"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," Alam said.