by Jerry Lambert, Asphalt Shingle Grinding Service, LLC
Recycled asphalt shingles (RAS) are becoming a valued commodity in the recycling community as well as the asphalt industry. It has been estimated that around 11 million tons per year of waste shingles are produced and, for the most part, disposed of in traditional landfills every year. Since asphalt is 100 percent recyclable, this is an unnecessary waste of resources. As either post consumer (tear-off) or manufactures waste (MW), RAS can be used to replace or amend the “recipe” asphalt producers use in their production of hot mix asphalt.
The value of RAS lies not only in the asphaltic cement content, (typically between 20 and 25 percent) but also the grit and fiberglass that make up the shingle, which some producers say adds desirable properties to their final product. Tear-off shingles have a slightly higher percentage of AC than MW since the heavier “grit” has been washed away through years of exposure.
Sourcing tear-off shingles starts with convincing roofing contractors that it is worth their time and effort to recycle. While there is not enough value in RAS to pay the contractor for shingles, there is enough value to reduce the cost of tipping fees when compared to traditional landfills. They may also benefit from fostering a reputation as a “Green Company” by encouraging their customers to recycle.
One of the drawbacks of tear-offs is the potential for a higher level of deleterious material such as plastics, wood, or metal. States that allow tear-off in their mixes limit the amount of deleterious material in the RAS to less than 5 percent. If the final product is highly contaminated, the RAS has no value to anyone other than a landfill.
The roofing contractor is the first and best line of defense for keeping undesired materials out of shingles destined for recycling. It is far easier to remove contaminates before they enter the shingles than to try and separate them after stockpiling and grinding. The contractor needs to be encouraged to keep the other waste products from the job separate from the shingles. Since this generally incurs an extra expense, a lower tipping fee in exchange for the contractor’s efforts to provide clean material could prove to be an incentive.
Paying a penalty for “dirty” loads could encourage them to keep the loads clean, but if it’s too high, it could drive the raw material the recycler needs back to the landfill.
Without cooperation from the roofing contractor, a shingle recycler will not have a reliable waste stream, incur high sorting costs, higher processing cost caused by contaminated material and end up with a less desirable product to market.
When stockpiling post-consumer asphalt shingles for recycling into RAS, a chief concern for the recycling facility is receiving and maintaining clean shingles, free from wood, plastic, metal, and other deleterious materials. The recycler must do a balancing act between keeping those who bring in the raw material happy, providing the end user with a desirable product and staying profitable. Two methods are most often used, each with its own drawbacks and advantages.
Some facilities try the “Set It and Forget It” method. They will set aside an area for the shingles to be dumped, and rely on the person dumping to leave a clean load. Then, when the area is full, machines shove it all together into a pile. While the initial cost is low, the potential for contaminates is high. There are countless piles throughout the country, many of which have been abandoned, creating a black mark on the industry.
To process this type of pile into RAS, additional handling and support equipment is needed. An excavator will feed a trommel screen to pull out the fines. The remaining material is fed into a four or six person picking station where the remaining deleterious material is pulled out. A magnet at some point in this line would also be advisable. The cleaned shingles are then either stockpiled again or fed directly into the grinding unit.
This method is high cost, machine and labor intensive and time consuming. It puts little burden on the roofing contractor or homeowner, and may provide the facility with additional revenue streams from the recovered materials. The revenue from those streams will be small and may not be enough to cover the higher processing cost.
Other facilities provide an area to dump shingles, plus dumpsters for the deleterious material and site personnel to go through the loads as they are dumped. A loader or excavator will spread out the load to make picking through it easier. If contaminates are found in the load, the customer is invited to use the dumpsters (in some cases for an additional fee) or take it off site. The cleaned shingles are stockpiled until processing is cost effective.
This method shares the responsibility for cleaning loads between the facility and roofing contractor or home owner. Some may see this extra effort as a disincentive to bring material to be recycled.
Whatever method is used, the end result must be clean raw material. Without that, the end product will be impossible to market. Without a market, shingles will simply be buried in landfills and a totally recyclable product will continue to be wasted.
According to the National Asphalt Pavement Association, in partnership with the Federal Highway Administration, nearly 1.65 million tons of RAS were used in new pavements in the U.S. during the 2013 construction season. That is a 135 percent increase from 2009. Asphalt paving contractors save millions of dollars in virgin asphalt binder, millions of cubic yards of landfill space is saved, and millions of barrels of imported oil have been saved by the use of RAS.
Waste handlers have an opportunity to tap into this market and create another revenue stream by becoming RAS producers and segregating, sorting, storing, processing and selling RAS to paving companies.
To make the most of this opportunity, the waste handler should always check local and state regulations first. The regulations vary widely from State to State and even municipality to municipality. RAS producers must also consider regulations regarding particle size, moisture content, and deleterious material.
These regulations impact the type of equipment used to produce the RAS.
Many “would be” RAS producers have started stockpiling shingles, only to find they do not have the correct permits and face fines, penalties and clean up cost. Some have faced bankruptcy after assuming they have the legal affairs in order only to find themselves in the middle of a turf war between state and local authorities. Too often, they have just abandoned the piles, leaving the clean up to others often at the expense of the taxpayer.
To be used in asphalt mixes for state projects, the particle size must meet the spec called for by the state.
While the AASHTO standard is 100 percent passing half sieve, most states require 100 percent passing 3/8 sieve and some producers require even finer. The grinding equipment chosen should be able to produce the right product size in as few passes as possible and, if possible, without the use of a trommel screen.
However, in some instances the use of an external screen will be necessary.
Moisture content is another factor in choosing the grinding equipment. Nearly all asphalt shingle grinding equipment needs to use water in the grinding process. Some use more than others. The higher the moisture content, the more expense the asphalt company must use to dry the product to an acceptable level. Since most RAS is sold by the ton, they understandably balk at paying for water weight that must be removed before it can be used.
As long as asphalt paving companies can make money by using RAS, its use will continue to increase. By keeping up with state and local regulations, and choosing grinding equipment that will produce the right particle size, with low moisture in as few passes as possible, RAS producers can tap into this expanding market.