Setting new standards
By Andrew Macklin
February 22, 2016 – Advancements are being made in the quality of recycled aggregates, and industry stakeholders want municipalities to take notice.
At the Ontario Good Roads Association conference, presented as a combined conference with the Rural Ontario Municipal Association, municipal leaders from across the province gathered to discuss infrastructure priorities and financial pathways to provide those resources.
During the presentation on recycled aggregates Edward Chiu, Senior Project Manager for Capital Planning and Delivery in the Transportation Services division of the Regional Municipality of York, discussed the Highway 427 that led the region to develop standards for recycled aggregates.
On that project, the municipality experienced a swell of 70mm on a new lane of pavement after one winter. When subgrade, asphalt and drainage were all ruled out as the cause of the issue, it was discovered that the recycled concrete material used in the mix had significantly higher moisture retention than the virgin aggregates materials used in the construction. That was a result of the high concentration of deleterious materials in the mixes, which had not been observed properly during construction.
Despite this negative experience with recycled aggregates, staff worked to develop a new policy for recycled aggregates that would reduce the inclusion of deleterious materials, providing a higher grade RCM that could be used in its construction projects. The result is a community who still highly regards the use of recycled materials and incorporates them into its road construction projects.
The introduction of standards and the use of quality control is at the forefront of some of the work being done by Aggregates Recycling Ontario (ARO). In a presentation from Paul Lum, Marketing Manager at LafargeHolcim, he explained that work that has been in creating widely-accepted standards for recycled aggregates.
For starters, the introduction of a standard means quality materials are used in construction. In demonstrating higher quality recycled materials, that perform as close to virgin aggregates as possible, the materials are likely to gain wider acceptance by municipalities in Ontario. While he did not provide a specific number, he noted that there are still many communities in Ontario that do not allow for the use of recycled aggregates in their contracts.
For Lum, ensuring quality has sometimes meant telling trucks with recycled materials to turn around and go elsewhere with its load when certain materials have not been removed from the aggregates mix. Those materials that can affect quality are: bricks, wood, topsoil, plastics, organic material, asbestos and gypsum/drywall.
The end goal for providers of recycled aggregates should be a material that meets the exact same regulations as the virgin granulars extracted from pits and quarries.