Recycled Material

Reusing Concrete, Asphalt, Even Tires Cuts Construction’s Environmental Footprint – And It Saves Cash, Too

By Pamela Dittmer McKuen

With a major portion of the road construction delivered, the Illinois Tollway’s 12-year Congestion Relief Program is expected to come in well under the $6.3- billion budget. A major contributor to the savings is the use of recycled construction materials, particularly asphalt and concrete.

MBL uses a hydraulic excavator to handle waste material at its Palatine, Ill., facility. (All photos courtesy of MBL.)

“We’re turning out $1 billion worth of work this year, following $1 billion last year,” says chief engineer Paul Kovacs. “These green initiatives not only serve an environmental purpose, but they allow us to take control of our costs.”

The tollway’s capital program, adopted in 2005, rebuilds, restores and expands the 286-mile system. A front-loaded endeavor, with the bulk of the work scheduled in the early years, it includes the south extension of Interstate 355 and implementation of open-road tolling. Both are completed.

As the work progresses, excavated concrete pavement is broken down into aggregate base for new pavement. Retired asphalt is processed into new mixes.

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“We’ve got more than a dozen processors—off-site processors, on-site processors and mobile processors that move down the road, leaving new stone behind it,” says materials manager Steve Gillen.

Last year the tollway began incorporating ground-up tires in stone matrix asphalt, a durable mix that withstands heavy loads. Discarded tires are abundant because tightened U.S. Environmental Protection Agency emissions standards prohibit their use as an energy source.

“Typically, a tire per ton goes into asphalt,” said Kovacs. “We’ll be producing nearly a million tons of asphalt in the next 10 years. That equates to a million tires.”

The tollway aggressively pursues opportunities in environmental responsibility. In partnership with contractors, transportation agencies and universities, it participates in research studies in a quest to provide pavements that are more economical and sustainable. Current studies are looking at warm-mix asphalt and recycling asphalt shingles into new mixes. Other initiatives include retrofitting equipment and vehicles to reduce emissions; and switching to alternative fuels and low-toxicity paint.

“Green highways” are the next hot trend in sustainability, says Bill Turley, executive director of the Construction Materials Recycling Association.

Another trend, the recycling and reuse of construction materials, has grown dramatically since he founded the Eola, Ill.-based trade group 15 years ago.

“Throughout the country, virtually all asphalt is recycled,” he says. “Concrete is not far behind, and building debris, that’s grown, too.”

The growth parallels that of the green building movement. The U.S. Green Building Council’s rating system for certifying green buildings, Leadership in Energy and Environmental Design (LEED), gives points for recycling and reusing waste and for using products with recycled content. Developers are clamoring for points.

MBL Recycling Inc., Palatine, Ill., says nearly all discarded construction and demolition materials can be diverted from landfills and re-used or recycled. MBL’s processing system includes both hand and automated sorting. Above left, incoming mixed debris goes through initial handling and sorting. Above right, mixed construction and demolition waste enter the crusher during processing.

MBL Recycling, a material-recovery facility in northwest suburban Palatine, Ill., attests to the upswing. The company opened its doors in late 2005. Over the last three years, the weight of materials received increased 22%.

“From 2007 to 2008, our tonnage intake went up by 5 percent,” says Wendy Gold, an owner in the family business. “So far this year, compared to 2008, our intake is the same. The good news is we are not starting off any worse this year even though the economy has definitelygotten worse.” For competitive reasons, she declines to give precise numbers.

MBL accepts about 20 different non-toxic pre-used construction materials including glass, wood, concrete, plumbing fixtures and plaster. It also tallies and creates LEED documentation for builders, a service that has jumped 50% in two years due to the popularity of the green movement.

The City of Chicago and the Village of Northbrook recently implemented a 50- percent recycling mandate on construction and demolition debris. Other municipalities are sure to follow.

In some parts of the country, developers are given rebates on their permits if they recycle, says Turley.

The re-use of recyclables is not without challenges. A frequently asked question is whether the quality of products made with recycled content equals those made with virgin materials.

“It’s a big concern,” says Illinois Tollway’s Kovacs. “One benefit of the tollway system is we have extensive amounts of temporary pavement. That gives us ideal areas, because of the short life of the pavement, to prove whether new concepts are going to be positive, and so far they have been.”

Some recyclables perform better the second time around, says Turley.

“Recycled concrete sets up better on the roadway because of the unhydrated cement that was left in there,” he says. “The cement not caught in the first place gets hard, and that’s a good thing.”

Used asphalt shingles are gaining momentum as an ingredient in hot-mix asphalt, but the possibility of asbestos raises alarm and costs.

MBL’s efficient, single-stream method of material recovery enables mixed recyclables to be transported together on a single truck.

“At one time a very small percentage of asphalt shingles contained a small amount of asbestos, under 1 percent,” says Turley. “That’s below the EPA guidelines for being hazardous. But as soon as you say ‘asbestos,’ state regulators require extensive testing, and that gets expensive.”

Even though advances are being made in creative re-uses for construction materials and debris, and contractors are increasingly eco-conscious, current market numbers for recyclables are weak. It’s a reflection of the battered construction industry. Fewer projects lead to less recycling and less demand.

“Prices are not real good right now,” says Gold. “There was a time last fall through the winter when no one was buying scrap metal. Now it’s come back a little. We used to get paid for cardboard. Now we’re thankful if someone takes it for free.”

“It’s a tough market,” says Turley. “If the federal stimulus package comes through with money for infrastructure, that will help us a lot.”