Gravel Shouldn't Travel: The Case for Recycled Aggregates

A few years ago, I saw an advertisement at a bus stop that read “What are aggregates in? Everything!”  And it couldn’t be more true. From the calcium carbonates in toothpaste, to the limestone in paper, and from the gravel and sand in concrete in the roads and bridges we rely on, aggregates are the foundation of modern life. Their impact on our economy is immense: Canadians use more than over 14 tonnes of aggregates per person per year, adding up to over 560 million tonnes of aggregates per year.  

Many years ago, a construction expert told me that “Gravel shouldn’t travel” and that has stuck with me ever since. The cost to blast, crush, wash, and test aggregates is quickly overwhelmed by the cost to ship them, and quickly climbs the longer the distance from a quarry or pit to the customer.

So, it is puzzling why we aren’t recycling more aggregates. These materials can be produced from the rubble of buildings, bridges, and roads - often near to where they are needed for new construction. It's like having a quarry right next door. Given high costs and 10-year time frames for licensing, often controversial, new quarries, recycling should be an obvious solution. While some municipalities, ministries, and builders are leading the way in advanced aggregate recycling, others go so far as prohibiting its use.  

Why is that? What I've heard is that there are no incentives for using circular materials, and even worse, they are considered substandard. Although modern production with strong quality control programs exist today, virgin material is preferred out of caution. In some cases, this stems from a bad experience with a single case of poor-quality recycled aggregates in the past.

It’s time to challenge these outdated assumptions. Consider the following:  

• Many studies have demonstrated that the quality of recycled aggregates can be equivalent to that of virgin aggregates. Dr. Soliman’s team from Concordia University has conducted research that demonstrates that recycled aggregates can meet the same quality standards as virgin materials. His team will present their findings at a special breakfast session on April 17 at the Canadian Circular Economy Summit in Montreal outlining the essential technical steps needed to ensure consistent quality.
• New quality standards are now in place for producers to follow.
• Many municipalities successfully incorporate recycled aggregates in tenders, enforcing strict contract language to guarantee quality.

Our call to buyers and builders is threefold:

1. Allow recycled aggregates in tenders.
2. Conduct pilot projects to collect data and demonstrate the quality of the material.
3. Require minimum recycled content for projects where materials are readily available.

Let’s advance circularity in our economy - because gravel shouldn’t have to travel.