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July 30, 2015

New law will help propel use of recycled concrete

By JON SILVER
Journal Staff Reporter

Photo courtesy of Stoneway Concrete [enlarge]
Contractors install concrete pavement in which more than 60 percent of the natural aggregate was replaced with recycled concrete aggregate.

As public transportation spending petered out amid the Great Recession, the mountain of rubble at Stoneway Concrete's quarry in Tukwila grew and grew.

The rubble was unneeded concrete aggregate that was piling up.

Greg McKinnon is the operations manager at Stoneway Concrete, a company that manufactures ready-mix concrete. He estimates that 5-7 percent of all the concrete produced in King County is returned, often coming back on the truck it was sent out on.

Road- and bridge-demolition work also generates concrete rubble that has to be hauled away.

“We spend hundreds of thousands of dollars trying to figure out how to reuse or dispose of it,” McKinnon said, referring to annual labor costs.

Concrete debris has been banned from Seattle landfills since 2012, and its disposal is restricted at landfills elsewhere in King County.

During the recession, the Stoneway didn't have anyone to sell the rubble to, McKinnon said, so it got dumped onto the company's growing heap, now reaching a half-million cubic yards.

Now that the economy has recovered from its swoon, the pace of road construction around Washington is picking up, and there's more rubble than ever. Even recycling facilities can't keep up.

Recycled concrete aggregate, or RCA, is created when existing concrete is crushed into a material of a specific size and quality, typically for use as fill or as road base.

In many states around the country RCA is also incorporated into new pavement. Despite the potentially large supply of RCA in Washington, there had been little urgency to follow suit here.

Bruce Chattin, executive director of the Washington Aggregates & Concrete Association, an industry group, approached the state Legislature to see if he could spur more action.

Highway construction was generating so much concrete debris that “we needed to start moving this material out,” he said. “Otherwise it's going to end up in fields and who knows where.”

(Editor’s note: The quote has been changed from an earlier version to insert a missing word.)

Working with legislators, Chattin's group helped craft a bill that encourages the recycling of aggregates and other transportation construction materials in Washington.

Gov. Jay Inslee signed the bill in April and it goes into effect on Jan. 1, 2016.

Starting next year, the Washington State Department of Transportation must use an average of at least 25 percent RCA on its transportation, roadway, street, highway and other infrastructure projects.

The bill allows exceptions for cost and availability, but the 25 percent figure is an annual benchmark, and isn't required for every project.

Other municipalities don't face the same minimum use requirement as WSDOT, but they at least need to make an effort to use more recycled concrete. For example, local governments with a population of 100,000 or more have to, as part of their contracting process for transportation projects, seek bids that include the use of recycled concrete. Assuming the costs are the same, bids that propose using more recycled concrete are to be accepted over bids that propose using less recycled concrete.

The final bill didn't require as much use of RCA as earlier drafts, Chattin said, but the version that did pass sailed through both chambers of the Legislature with unanimous votes.

“There was some good push back on (the earlier draft),” Chattin said. “This has to be something people want to do than are forced to do.”

WSDOT issued a report in 2009 recommending the use of RCA in new pavement in Western Washington, citing the high quality of the aggregate in existing pavements here. But the agency did not change its practices after that.

(Editor’s note: The story has been corrected to say that WSDOT did not change its practices after the pavement report was issued.)

“WSDOT is a very thoughtful agency,” Chattin said. “They don't make quick decisions.”

Greg McKinnon of Stoneway Concrete said his company, along with Gary Merlino Construction, demonstrated the use of RCA in new concrete pavement earlier this month to area concrete specifiers, including WSDOT, King County, the city of Seattle and Boeing.

The demonstration, which took place at Stoneway Concrete, involved placing concrete in which more than 60 percent of the natural aggregate was replaced with RCA produced at Kangley Rock & Recycle in Tukwila.

The recycled concrete performs just as well in pavement as new concrete, McKinnon said.

“It's the same thing,” he said. “In all of the testing we've done to date, it performs as well as natural aggregate.”

Much of the push for the use of recycled concrete is motivated by environmental considerations such as reducing waste and greenhouse gas emissions, but there are immediate benefits as well.

“The biggest cost with materials is transportation,” McKinnon said. In urban areas it's less expensive to truck in RCA from nearby than to haul natural aggregate from a sand and gravel pit located miles away.

Chattin said using RCA for paving projects only scratches the surface of what's possible. He envisions wider uses, such as for commercial building construction.

“It just takes one designer who says ‘I'm reaching for this level of LEED,'” he said. “We have the market, materials and people to make that happen.”


 


Jon Silver can be reached by email or by phone at (206) 622-8272.




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