DCN ARCHIVES

October 6, 2010

JEAN SORENSEN

Interlocking concrete blocks, where weight is critical and used for holding back mass, have been users of recycled concrete.

LEED helps jump start interest in concrete recycling

VANCOUVER

The concept of re-using old concrete in ready-mix is still in its fledgling state, but it is a concept that is growing both in Canada and internationally because of the ability to earn LEED points.

“We have dabbled in it,” said commercial accounts manager Mark Leslie for Lafarge Canada Inc. in Coquitlam, B.C.

But, the drawback to re-using old concrete reconstituted into aggregate-sized pieces lies in quality control.

Lafarge has produced a foundation and footing mix with recycled content material, said Leslie, but it is only used in low-strength applications.

It is only suitable for residential use and not even durable enough for sidewalks.

He said that work is progressing now at the company’s laboratories in France at finding ways to quantify and increase strength requirements when old concrete is made new again.

“We are probably leading the world,” he said, adding that such research requires capital to ensure product integrity.

Ocean Concrete vice-president and general manager Larry Baloun, also vice-president of the BC Ready Mix Concrete Association, said his company is currently conducting research at its own lab on using old concrete in new ready-mix applications.

“We have to adhere to CSA standards,” he said, adding that one of the challenges is ensuring that product from varying sources meet a uniform standard.

“We have also done a literature review (of what is happening in other countries) to make sure we are not re-inventing the wheel,” he said.

However, products differ and strength requirements must be derived from local materials.

Baloun said the use of recycled concrete in fresh ready-mix lies in lower-strength applications and it’s a huge market when residential housing is considered.

Baloun said that it’s misleading to think that companies have not been recycling concrete.

“We have been doing it for decades. We are on our third generation reclaimer at Granville Island,” he said, referring to the new machine that will be installed later this year. The reclaimer is able to wash out the cement and reuse the aggregate in concrete.

Companies like United Lock-Block Ltd. and Burnco Rock Products Ltd. are using recycled concrete in interlocking concrete blocks commonly used for retaining walls.

Mike Kask, in operations at Langley’s Burnco plant, said its main value lies in products where weight, not strength, is required.

The green value comes in being able to reuse old concrete that is local rather than having to barge in or truck in aggregate from long distances.

“There are the transportation and greenhouse factors,” he said.

At United Lock-Block (ULB) Ltd., product is made from recycled concrete, recycled concrete aggregate, as well as recycled latex paint.

Bert Almeida, manager of ready-mix at ULB in Richmond, said that recycled concrete was originally introduced into the company’s products as a means of cost control.

Contractors can dump concrete for free, as long as it meets ULB’s specifications, and it is processed through a 42-inch jaw crusher, then a cone crusher for secondary breakdown and onto looping sifting tables, that take oversized pieces back to the cone crusher.

Some of the material, besides going into the company’s Lock Blocks, also goes for road base material.

ULB has started a new company known as Green-Stone Ethical Concrete Ltd.

Almeida said Green-Stone will be consumer-based and go after the residential market.

“Right now we are going through the testing process,” said Almeida.

Old concrete has long been used as a road base with large and smaller companies grinding it on site and offering it to roadbuilders.

Ecowaste Industries, which owns and operates the Richmond landfill, takes old concrete, at a tipping fee, and breaks it up into smaller pieces by running over it with large equipment. It is then used as a road base material for the network of roads through the landfill.

“We have a 600-acre site and that’s a large property with internal roads that we maintain, plus we have a bunch of tenants on site,” said Ecowaste general manager Tom Land.

The good news is there is no shortage of raw material this year.

“We have definitely seen an upward trend in the last year,” he said, estimating that volume is up at least 30 per cent over this time last year.

He said that he believes it is due to an increase in renovation work.

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