Ontario’s professional engineers are throwing their support behind a moment to specify the increased use of recycled crushed aggregates (RCA) in road construction projects.

Members of the Ontario Society of Professional Engineers (OSPE) recently participated in a webinar to discuss how increased RCA use can lower project costs and carbon emissions. 

The session emphasized the need to expand and maintain Ontario's transportation infrastructure to keep up with continued population growth and an increasing state of good repair backlog and how using RCA can deliver more from municipal capital budgets while also helping them reach their net-zero targets.

Dr. Salman Bhutta, Principal Engineer at Engtec Consulting, delivered a keynote presentation to share findings from Engtec's 2024 research report demonstrating RCA gradation equivalency to primary aggregates.

He told attendees the testing demonstrated comparable performance in terms of load-bearing support in pavement structures and no compromise to the structural integrity of the pavement when using crushed concrete. The research concluded there is no need to increase layer thickness when using crushed concrete in pavement structures.

"Over the last 20-25 years, there has been significant improvement in these materials, including both their quality and quality control processes," said Dr. Bhutta. "RCA is a cost-effective and environmentally friendly alternative to primary aggregates. It supports sustainability goals, without compromising structural integrity or long-term performance."

RCA is reclaimed asphalt pavement and/or concrete, readily available from the millions of tonnes removed from construction sites across Ontario as roads are repaired, bridges are maintained, and other critical infrastructure is replaced and expanded.

Raly Chakarova, Executive Director of the Toronto and Area Road Builders Association (TARBA) indicated that the industry has long supported the use of RCA as a way to lower carbon emissions associated with long-haul trucking, reduce pollution and traffic congestion, extend the life of non-renewable resources, and promote a circular economy.

"Concrete and asphalt have already met performance specifications when originally used. When reclaimed, they undergo an additional rigorous process of crushing, screening, testing, and quality control to be repurposed for their application as construction material in new projects," said Chakarova. "Use in Ontario and internationally has shown that RCA is a high-performance material, with numerous construction projects and studies concluding that its geotechnical properties are equal and sometimes superior to primary aggregates."

180 million tonnes of aggregates are used annually in Ontario, with more than 50 percent used in roadways, bridges, and tunnel construction. However, less than seven percent currently come from recycled sources, with much attributed to the Ontario Ministry of Transportation in the construction and maintenance of its 400-series highways.

TARBA is leading a coalition of industry associations to increase awareness and adoption of RCA across Ontario. OSPE is a coalition member.

"Advances in material science and recycling technologies have demonstrated that RCA performs comparably to traditional alternatives in many applications. Most significantly, the use of RCA reduces the demand for valuable finite natural resources, such as sand, gravel, and crushed stone," said Sandro Perruzza, CEO, OSPE. "The use of RCA in engineering designs will dramatically reduce the amount of waste going to landfill while decreasing road congestion and the associated carbon emissions, both favourable outcomes for sustainable development. The OSPE is a proud coalition member and is happy to endorse using RCA in construction to build Ontario's future."