- Posted by: Ana
- Category: Roofing
Old Asphalt shingles are easily recycled, and have proven to be a win win for the municipalities’ who have accepted their use in asphalt roads. When the old roof is being torn off, the workers must separate the asphalt shingles from the other debris, and only load the shingles into the dump truck. This requires the individual contractors to train their personnel how to separate the material so it is ready to be recycled. The dump truck then delivers this “clean load” of asphalt shingles to the recycle facility. After it is dumped, the load of shingles will be will be chopped and ground into small pieces. The chopped shingles are passed over a magnet to remove any nails. The finished product, commonly referred to as RAS, is then ready to be used in Hot Mixed Asphalt.
The use of RAS in Hot Mix Asphalt (HMA) pavement has shown to have a number of benefits.
Benefits shown from many studies include:
•Recycling thousands of tons of usable material
•Reducing the amount of asphalt shingles being put into landfills.
• Reducing the amount of miles traveled by dump trucks traveling to outlying landfills.
•Increased stiffness of asphalt roads
•Decreased road cracking
•No effect on moisture sensitivity
•Decreased susceptibility to rutting
•Decreased optimum content of virgin asphalt cement.
Studies have been conducted in which portions of highways and roads have been paved with asphalt containing recycled shingles and have been monitored over time. Many laboratory studies have been conducted and may be found on the Technical Reports and Articles pages at Shinglerecycling.org.
Because of the benefits shown by using RAS in HMA pavement, a number of states allow a certain percentage of RAS to be used in HMA pavements.
Florida, Georgia, Indiana, Maryland, Michigan, New Jersey, North Carolina, Ohio, Pennsylvania, Oregon, Minnesota, Illinois, Texas, and Alabama.
- What are the costs?
COSTS: Debris segregation = $4-8 / ton; grinding (no-post screening) = $14-22 / ton (depending largely on whether you contract out the grinding or do it yourself)
- What is the Value of the RAS?
VALUE: RAS is worth the percent asphalt in it x price per ton asphalt. Old Asphalt shingles typically have 20-25% asphalt content. Price of asphalt varies widely. The value is off-set by the cost of the hot-mix producer having to potentially put in place new bins to add the RAS, the cost of new mix designs with the RAS (which may include need for different recipe of rocks and sand that can be more costly), and the potential cost of using softer asphalt to off-set stiffness of RAS asphalt at higher concentrations of RAS. HMA producers should consider RAS as a new recycled material because of its relatively high Asphalt content. RAS becomes a partial replacement of the virgin Asphalt. In the past, HMA producers have reported savings of approximately $1 to $3 per ton of finished HMA product with the use of 5 percent RAS. The total, average cost per ton for HMA production and sale varies with the grade of pavement and geographic location. Studies have indicated a savings of up to $3 per ton of final HMA.
- What are typical design specifications for Road Asphalt using RAS?
Designs: 25-40% total recycle content (replacement of asphalt which could include RAS and/or RAP) may include the use (or may require by state spec) of softer asphalt. Soft asphalts (depending on market) may not cost more or only 10-20/ton more, but typically cost $35-55/ton more (Some markets higher than that; like in the North West). Soft asphalts may also be difficult to come by in a market too if there isn’t demand, or given current refinery operating strategies. There are “rejuvenators” that are sold that are supposed to revitalize the stiff / old asphalt in RAP & RAS; I can’t say that these are widespread. They are typically hi-flash hydrocarbons
In reality, while asbestos was commonly used in many asphalt roofing materials, asbestos was rarely used in the shingles themselves. It is acknowledged by the asphalt shingle manufacturers that between 1963 and the mid 1970s, some manufacturers did use asbestos in the fiber mat of shingles. Manufacturer information on how many asbestos-containing shingles were sold is not available, but the amount of asbestos used in shingles was typically less than 1% [NESHAP defines ACM as any material containing more than 1% asbestos] and it was only in a small portion of the manufacturers’ production. Unfortunately, less is known about the possible presence of asbestos in imported roofing coatings.
Because of concerns raised over the possible presence of asbestos in asphalt shingles, several shingle recyclers have done extensive testing to confirm that asbestos is not a concern. The Construction & Demolition Recycling Association (CDRA) has compiled (and continues to compile) a database of test results for asbestos in asphalt shingles. These test results come from facilities that recycle asphalt shingles and from exploratory testing. Individuals interested in the raw data should contact the CDRA. In addition, individuals with additional sampling data are greatly encouraged to share the results with the CDRA so the information can be posted on the Shinglerecycling.org website.
If asbestos testing is mandatory it is possible to test each load. The loads would be segregated as they arrive at the facility and have a test facility set up on site and test each load before they are ground-up.