An Energetic Application

Features - Equipment News

As horizontal grinders are put to use to process asphalt shingles, they are re-directing petroleum from the landfill to an end market.

July 15, 2010
Larry Trojak

On many different levels, recycling asphalt shingles might be one of the most beneficial material recovery efforts being undertaken today.

From the perspective of the hot mix asphalt producer, recycled asphalt shingles (RAS) can provide a cost-effective additive to virgin asphalt material, thereby reducing operating costs and serving as a buffer against the incessant “spiking” of oil prices.

Asphalt users (paving and construction companies, for example) reap the benefits of being able to offer customers a product that, in many cases, has been shown to be far more durable than virgin-only mixes.

And finally, roofing contractors who choose to recycle the shingles being removed, can both tout their “green” building practices to the homeowner, and potentially benefit from a lower disposal cost.

It is little wonder, then, that more companies are making forays into shingle recycling—some enduring with a measure of success while others experiment temporarily.

One firm that has established itself as a major player in this still-evolving market is Houston-based Sustainable Pavement Technologies (SPT).

Armed with a high-powered horizontal grinder and a penchant for material cleanliness, the firm has set up operations in Houston, San Antonio, the Dallas-Fort Worth area and Austin in Texas, as well as one in the upper Midwest, and could be poised for nationwide growth.

Though officially in business for about three years, SPT’s business plan has been in the works for longer than that. According to company president Jeff Wanic, SPT’s roots are grounded in a belief that recycling in general is a positive endeavor.

“My history of looking at the feasibility of recycling goes back about 15 years,” says Wanic. “As a chemical engineer in the plastics division of a major chemical company, my job often involved looking at ways to reduce the amount of plastic material going into land ill, finding beneficial re-uses for their products, and so on. Seeing what was possible essentially drove the decision to establish SPT as a multi-faceted recycling company. So while shingles are currently the major component of this operation, we also are looking at other ways to reuse C&D debris, pallet wood, tires, and more.”

Wanic says the decision to focus on shingles was based on both his research background and having friends in the construction industry who provided input.

“Actually, some of my first ideas centered around alternative fuels and bio-fuels, but I seemed to keep coming back to shingles, shingles, shingles. Because they can contain between 20 percent and 30 percent oil, I felt there was really no reason they should be going into a landfill. But, until now, the economics to make it work—specifically getting them into a form where they have value—cost too much.”

What changed to make shingle grinding a feasible effort for SPT was, in part, its acquisition of a grinder that was efficient and productive, yet could give the company the quality product its customers demanded.

Seeing what was possible essentially drove the decision to establish SPT as a multi-faceted recycling company. While shingles are currently the major component, we also are looking at other ways to reuse C&D debris.” – Jeff Wanic, SPT

“Obviously, our primary market for the RAS is hot mix asphalt producers, and they have some very demanding DOT-generated specs for the material that we have to meet,” says Wanic. “For Texas, the state spec for gradation says that 100 percent of the material has to pass a ½-inch sieve; 90 percent needs to pass a 3/8-inch sieve. If we don’t meet that spec, we simply don’t have a sellable product. Over the last few years we’ve tried a number of different makes, sizes and configurations of grinders and feel that we’ve found the ideal tool in the Morbark 4600XL.”

Wanic says a recent visit to his site from the Texas Department of Transportation (TxDOT) resulted in perhaps the best endorsement a company can hope for.

“This was a lead engineer for TxDOT who, after looking at our product, said that it was the best looking material in terms of gradation that he had ever seen. That’s exactly what we—and the hot mix guys—like to hear.”

The gradation to which Wanic refers is the particle size distribution across a specific sampling. In the hot mix industry, it is generally believed that the finer the product, the better. That, however, only goes so far, says Wanic. Get the material too fine and then those same customers will suddenly be dissatisfied.

“So it can’t be like dust and it can’t have chunks in it,” he says. “On a regular basis, we are generating anywhere from 28 to 34 loader buckets of material per hour. That translates to about 110 tons per hour of excellent product created by a single pass through the grinder. We’ve been extremely satisfied with what we’re getting with the Morbark unit.”

While grinding can generate the proper sized product SPT needs, the cleanliness of the material is as important—if not more so—than its actual size. “In most cases, the material needs to be cleaned prior to grinding to remove contaminants and other non-shingle debris,” says Wanic.

“I say ‘in most cases’ because in addition to post-consumer shingles, we also take in post-manufactured material—scraps and discards direct from the shingle manufacturer. We have multiple stages of cleaning to get it to a point where it can go into the 4600. How clean it needs to be depends, again, on state DOT specs.”