The Northeast Recycling Council estimates that more than 11 million tons of asphalt shingles are scrapped in the U.S. each year; 10 million from installation tear-offs and reproofing jobs and another 1 million discarded as waste by asphalt shingle manufactures. The U.S. Environmental Protection Agency estimates that shingle waste makes up 8% of the total building-related waste stream and 1% to 10% of annual construction and demolition debris, representing a tremendous burden to landfills across the country.

Due to their material composition (asphalt vs. wood, metal and other construction materials), shingles are usually separated from other construction-related waste debris, making the discarded roof protectors a prime candidate for the recycling stream. Recycling facilities have responded, and new technology has created some money-saving opportunities for recycled shingle markets- most notably as an additive to asphalt paving preparations. Using hot mix asphalt with only 5% recycled shingle material can save $1 to $3 per ton of hot mix asphalt, as well as improve the quality of hot mix asphalt used in paving.

Concerned by the quantity of discarded construction debris that was ending up the country’s landfills and knowing that a lot of it could be put to good use, Mark Pahl saw an opportunity and founded Dem-Con Shingle Processing. Dem-Con Companies, LLC, based in Shakopee, Minnesota, was founded in 1985, and at first their business was mainly a construction and demolition debris landfill. Over the years, the landfill has evolved to not only demolition and construction debris, but also certain types of industrial wastes and impacted soils.

“Basically, we handled all nonhazardous waste, with the exception of household trash.” Pahl says. “Construction and demolition material is still the primary focus of the largest portion of our business. We encompass an area that includes the Minneapolis/St.Paul metro along with surrounding rual communities. We process a lot of different types of construction debris before it enters the landfill, which includes pulling out wood, metal, cardboard, concrete, asphalt, etc. There is a lot of value in removing those materials prior to landfilling.”

Researching have found that using recycled asphalt shingles in hot mix can actually improve the pavement’s performance by increasing its resistance to wear and moisture, and decreasing deformation, rutting and thermal fatigue and cracking. Currently a substantial portion of asphalt shingle recycling involves mixing 5% ground-up shingles with hot mix asphalt in road paving and cold patch applications. Pahl is excited by not having to landfill shingles anymore.

“From our local level, each year we process about 10,000 tons of manufacture scrap.” Pahl says. That material comes right from the single manufacturer as factory rejects or end runs. Add to that additional scarps from reproofing existing homes, hailstorms, demolition, etc., and the amount increases to somewhere between 25,000 up to 40,000 tons that used to go directly into the landfill. And that’s just at our Shakopee location. Imagine the effect nationwide.

Enlisting a wood processing trommel for assistance

According to Pahl, the material that Dem-Con receives as factory rejects is ready to be processed without any special preparation because the material is void of any contaminants or construction debris. Shingles origination from reroof projects create a bit more of a problem and necessitate some cleaning and filtering of other materials since this debris often arrives at this facility mixed with a variety of other substances, including tin, metal, roof vents, board, etc.

“We remove all the debris that doesn’t contain asphalt on a sorting line,” Pahl explains. “Essentially the material is spread out on a conveyer belt and we have laborers that manually remove all nonasphalt containing materials as they move along the sort line. From there, the shingles are ready to be ground. Generally the grinder then directly feeds the material to a trommel screen to create the desired end product used for the asphalt hot mix.”

Pahl uses a grinder designed specially to process shingle material. The raw asphalt shingles are first ground to under a 1/2-inch minus size, and that material is then fed to a trommel to reduce the ground shingle material to an even finer size. Dem-Con purchased a trommel until built by Wildcat Manufacturing, based in Freeman, South Dakota, to assist in streamlining the process. “Our spec at the hot mix plant varies across the country but 1/2-inch minus is fairly standard,” Pahl explains. Some states, including Minnesota, require an even finer sizing and that’s when the trommel screen is really the only way you can get a product down to the size they want cost-effectively.”

The trommel involves different screen sizes to achieve the desire end result. For example, Minnesota Department of Transportation (MDOT) requires the end material to be of a consistency that Pahl describes as similar to a coarsely ground coffee type of material. As the material passes through the different screens, each screen setting gets smaller and reduces the material to the desire end consistency Pahl explains the process.

“The No. 4 sieve is somewhere in between 1/8 and 3/16 inch,” he explains. “The spec calls for 90% of the material passing the No. 4 sieve and 100% passing the 1/2 inch. Some states spec a material that is a bit coarser; all are different. We have found that more and more states are requiring a finer material so the Wildcat trommel will play a more important role in the upcoming seasons. The Wildcat trommel with multiple sections of screen that we can adjust quickly helps us to create a lot of variables and flexibility on how we size our final product.”

All of the overs (material that is too larger to meet the specs) are recycled back through the grinder and end up getting ground down further, a closed loop process that results in all the raw material used and no waste-so no asphalt material ever ends up in the landfill. Everything gets used.

Expanding and streamlining the processes

Dem-Con has reached out to recyclers across the country and worked with state Departments of Transportation (DOTs) to expand asphalt shingle recycling nationwide. This has required establishing an in-depth knowledge of the asphalt paving industry and the hot mix process used for completing road construction and parking lot projects.

“When we were getting this started, a lot of state DOTs didn’t have a hot mix spec using shingles, but more and more are coming online,” Pahl says. “Whatever the DOT spec is, we are able to meet it. Were competing with virgin asphalt because that’s what the asphalt recovered from the shingles replaced. Using shingles in the mix allows the  hot mix producer to lower the use of the high price virgin asphalt. So its really a cost saving to them and this is what enables this process to be economically viable.”

Dem-Con works hard to presell a majority of final product, a necessary component of Pahl’s business operation because of preparing product specifically for so many different state DOTs and asphalt suppliers. “We have quite a bit of money invested in the process and we make sure the product has a home before we process it,” Pahl explains.”We are also working with local recyclers who are involved with collecting shingles throughout the country to help them as well. So there are times where we may assist  the company, just trying to market the material, before we ever show up to process it. It benefits everyone to be as cost-effective as possible so we will assist in whatever way possible to try to drive the process.”

Growth and expansion expected

According to Pahl, asphalt shingle recycling has been occurring for several years, but the process has just recently become more refined, mainstream and is gaining efficiencies. As more states adopt specs for hot mix materials, he is optimistic that the industry will continue to grow.

“The key for expansion is to get more and more state DOTs onboard,” Pahl explains. “Most hot mix manufactures wont put any material in their mix unless its approved by the DOT. So, if you don’t have the state DOT approving the material used on their road projects, recyclers and processors aren’t going to make the investment in the equipment or technology necessary to make it an efficient business model. We have been an integral part of advancing the process here in Minnesota by working with DOT, the Minnesota Pollution Control Agency, as well as hot mix producers and associations in getting ground tear-off shingle material approved as a permissive spec throughout the state.”

Jason Haus of Dem-Con Cos. LLC, Shakopee, Minn. , said an end market exists for scrap roofing shingles, provided state transportation agencies could not send a green light signal to hot-mix asphalt (HMA) plant operators.

At the 2010 C&D World Conference & Exhibition, which was March 28-30 at the Rio Casino Resort in Las Vegas, Haus outlined how his company went about cooperating with the Minnesota Department of Transportation (MnDOT) and HMA plant operators to change his company’s asphalt shingle diversion rate from 3 percent to 75 percent in just four years.

Haus, who noted there are some 11 million tons of scrap asphalt shingles generated annually, says insight he gained from meeting with HMA plant operator’s convinced him the creation of a permissive spec recycled asphalt shingle (RAS) spec from MnDOT would be a key to gaining acceptance for his product.

In the four-year span from initial meetings to the creation of the spec, Dem-Con also researched and invested in processing methods and conducted numerous tests to assure customers that the presence of asbestos was a rarity and occurred at extremely low levels when it was present.

Rich Krock of the Vinyl Institute, Alexandria, VA., remarked that about 76 percent of vinyl consumed goes into building products, such as pipes and fittings, vinyl siding, windows and doors, decking and fencing and flooring.

He said since pipe manufacturers have their own exclusive compound formulas, they often accept only their own products back as scrap. “It’s a little bit of a challenge, “said Krock.  Vinyl siding can baled and shipped and was starting to be used by siding manufacturers as a substrate material, said Krock.  He singled out Cedar Boards vinyl siding made by CertainTeed Corp., Valley Forge, PA., which is made from 60 percent recycled material, as an example of this type of siding, which has a recycled-content substrate.

As published in C&DR May/June 2010

In a presentation at the 2010 TERRA Pavement Research Conference, Curt Turgeon, a pavement engineer at Mn/DOT’s Office of Materials, discussed the department’s use of asphalt obtained from tear-off roofing shingles scrap (TOSS) in pavement.

Nothing that about 230,000 tons of discarded shingles go into Minnesota’s landfills every year, Turgeon said there was initial enthusiasm about this source of asphalt when it was first discussed several years ago.  “But then reality set in!  People pointed out that shingle asphalt is not paving asphalt.  They worried that spending 10 to 30 years on a roof probably doesn’t improve the asphalts’ qualities.  Furthermore, shingles come off roofs along with a lot of junk—and they might contain asbestos.”

Accordingly, Turgeon said, it was decided that there would need to be both quality control and limitations on how much asphalt from TOSS could be included in pavements.  To address the asbestos issue, the Minnesota Pollution Control Agency funded a Mn/DOT research project.  Testing The office of Materials test 17 different asphalt samples with varying combinations of asphalt from four sources:

• Tear-off roofing shingle scrap (TOSS)
• Manufactured waste shingle scrap (MWSS)
• Reclaimed asphalt pavement (RAP; all from a shingle source except in one formulation)
• Virgin Asphalt

A chemistry test showed that, when subjected to bending stress, four of the samples (see table) with formulations likely to be used in pavements had essentially identical properties.

Another test showed that, in general, the more old asphalt from tear-off shingles is included in a mix, the stiffer the mix is at low temperature—and therefore the more likely it is to exhibit thermal cracking.

Asbestos in pavement?

Turgeon referred to the possibility that TOSS might contain asbestos as a “lighting rod issue”. However, in tests conducted by a third-party laboratory on more than 1,000 samples taken from DemCon, a shingle recycler in Shakopee, Minnesota, no asbestos has yet been found, he reported.  Turgeon directed anyone with questions about the asbestos issue to Wayne Gjerde at wayne.gierde@pca.state.mn.us.

Purity standards

Turgeon also discussed strategies for avoiding contaminants in TOSS.  Working with DemCon, Mn/DOT has developed a four-part strategy:

• Charge roofers less if they pre-sort and bring in cleaner loads.
• Workers pull out the largest non-shingle material such as boards and pallets.
• Workers hand-sort materials moving past them on a conveyor.
• Run the resulting material through a shredder that also pulls out nails with magnets.

Mn/DOT’s standard for the resulting material is that 100 percent must pass through a ½-inch sieve, 90 percent must pass a #4 screen and there must be less than .05 percent “deleterious material”. Turgeon added that the maximum amount of deleterious material is half a percent of five percent—that’s pretty low.  However, a slightly larger pieces of TOSS occasionally gets through—so you have a little ‘tab’ popping up on the surface of the pavement, and that doesn’t seem to be much of a problem.” Standards for MWSS and TOSS are part of Mn/DOT’s bituminous standard and can be found at www.dot.state.mn.us/materials/bituminousdocs/Special_Provisions/2009/Shinlges/Table%202360.3-B2_Agg_Reg_2010.pdf.  LTAP –Richard Kronick, LTAP freelancer

Source: Minnesota Technology Exchange: ‘Pavement Conference’

Recycling of tear-off asphalt shingles is ready for full-scale, commercial operations.  That’s the message from two companies that sponsored a special event held in Shakopee, MN on October 21.  The main barrier is the need for a permissive materials specification from the Minnesota Department of Transportation (MnDOT).

Dem-Con Recovery & Recycling, a subsidiary of Dem-Con Companies, is a local recycling company that has recently invested in the equipment and systems needed to turn tear-off shingles into a culpable recycled product.

Once residential asphalt shingles have been sorted and cleaned to remove contaminants and then ground, the product can be introduced into the mix at hot mix asphalt (HMA) plants.

One recent study indicated that on a statewide basis, tear-off shingles recovery could reach at least 156,000 tons per year by 2012.  Given the oil content within tear-off shingles (at least 20 percent), about 32,000 tons per year of binder (virgin liquid asphalt oil) would be conserved by recycling shingles into HMA pavement.

Rotochopper Inc. is the equipment manufacturer that sold its “RG1” grinder to Dem-Con.  “We have seen numerous successful tear-off shingles recycling businesses around the United States and Canada” says Vince Hundt, vice president of Rotochopper.  “Our RG1 grinder can produce a high-quality, finely ground RAS product in one pass.  Recyclers like Dem-Con will be able to sell a valuable recycled product to HMA producers”.

Plehal Blacktopping installed the asphalt pavement at Dem-Con’s Shakopee plant.

“Our paving crew didn’t notice any difference,” says Jack Van Remortel, president of Plehal Black-topping. “The bituminous mixture was installed using normal equipment and procedures.”

MnDOT has been a leader in the country among other state departments of transportation when it adopted an earlier specification in 1996 for the use of manufacturers’ shingle scrap for use in HMA.

This “new” shingle scrap comes from the three shingle manufacturers located in Minnesota.  Since then, MnDOT has participated in five demonstrations of road construction projects that have successfully incorporated tear-off or “used” shingles into HMA pavements.

MnDOT is currently considering how best to write requirements for an updated new materials specification that would allow tear-off shingles in HMA.

Source: Asphalt Contractor December 2008, Paving Innovations

Dem-Con Recovery & Recycling, a subsidiary of Dem-Con Companies, Shakopee, Minn., is ready to recycle tear-off asphalt shingles and is awaiting for the proper materials specification to be developed by the Minnesota Department of Transportation (McDOT) in order to meet market demand.

CMRA member Dem-Con is a mixed C&D recycling company that has recently invested in the equipment and systems needed to turn tear-off shingles into a valuable recycled product.  Once residential asphalt shingles has been sorted and cleaned to remove contaminants and then ground, the product can be introduced into the mix at hot mix asphalt (HMA) plants.  HMA plants manufacture asphalt mix that paving companies use for making flexible bituminous pavement for roads, parking lots, driveways.

Commercial Asphalt Co., a nearby HMA producer, has successfully tested the use of asphalt shingles (RAS) material produced by Dem-Con. Commercial Asphalt, a subsidiary of Tiller Corp., manufactures high-quality asphalt.  Commercial has been making and using recycled asphalt pavement (RAP) from old bituminous roads for more than 20 years.  Commercial has extensive experience with the quality control procedures needed to produce high quality products.  They believe the time has come for tear-off shingles to be a part of a viable HMA product.

“Recycling of tear-off shingles will be a significant new step forward in abating the need for land filling shingles,” said Jason Haus, vice president, Dem-Con. “Our landfill along receives about 50,000 tons per year of roofing waste.”

Dem-Con is serious about is commitment to produce the highest quality tear-off RAS product. “Based on other demonstrations in Minnesota and in other states, we not only invested in a new shingle grinder, but also a sorting and cleaning system to assure we can meet any material specification our customer’s needs,” said Haus.  “The quality and cleanliness of the RAS will differentiate companies that are looking to enter this market.  We have received samples of very high quality and low quality RAS and the main difference is the effort put forth to ensure the cleanliness of the product.  The cleaning and sorting process to eliminate foreign debris is critical in producing a high quality RAS.

“The next neede step for large scale recovery of tear-off shingles if a permissive MnDOT specification similar to the specification granted for manufactured scrap shingles,” said Haus.

“Once the permissive specification is determined and assuming virgin asphalt prices remain high, the land disposal of shingle material will become rare.  Our industry is prepared to provide his material to HMA producers on a large scale.  Without the MnDOT space, we will have to continue land filling valuable tear-off shingles.  We have a great opportunity to reduce materials being land filled while providing a substitute for virgin asphalt at a lower price.  Recycling and positive economics have always been a large debate within the solid waste field and with recycled asphalt shingles, there is very little debate, it just makes sense.”

“We have the capacity to do this,” said Robert Keuhborn, manager of product design/quality control, Commercial Asphalt. “Recycling tear-off shingles is now a well proven, feasible technology.  When we bring this new technology up to full scale, it will help us conserve asphalt cement and save money.  Part of this savings can be passed along to the driving public.  The time has come for tear-off asphalt shingles to be accepted as another standard recycled material into hot mix asphalt.  Tear-off shingles should be part of permissive materials specification similar to the way RAP and manufacturers’ asphalt shingle scrap are considered by MnDOT today.  In order to consume any meaningful quantity of tear-off shingles, the HMA industry needs a permissive specification because we want to produce MnDOT certified mixes on a standard, full scale basis.”

One recent study indicated that on a statewide basis, tear-off shingles recovery could reach at least 156,000 tons per year by 2012.  Given the oil content within tear-off shingles (at least 20%). About 32.000 tons per year of binder (i.e., virgin liquid asphalt oil) would be conserved by recycling shingles into HMA pavement.  Using a conservative price estimate of $400/ton of liquid virgin binder, this savings has an equivalent of about $12.5 million.

Source: C&D World: Industry News – January/February 2009

Recovery & Recycling Overview

Green doesn’t happen overnight; it happens daily…

Dem-Con Recovery & Recycling was established in 1999 as one of the first facilities in the Twin Cities to recycle mixed construction debris.

Over the past decade, processes have improved and currently, the facility has been expanded to nearly 40,000 sq. ft. of covered floor space dedicated to material recovery. This facility was designed to be a comprehensive service center that accepts a wide range of materials. The building handles demolition, construction, and mixed solid waste (household trash). This facility is primarily dedicated to the recovery of construction and demolition debris. A mechanized sorting system was installed in this facility in 2008…

Read more on Dem-Con’s Recover & Recycling….