HOUGHTON - Zhangping You is taking recycling to a whole new level.
You, associate professor of transportation engineering and materials at Michigan Technological University, is conducting a study using recycled asphalt roofing shingles. Every year, 11 million tons of asphalt roofing shingles are dumped into landfills, he said. You, with his graduate students, are using recycled asphalt shingles to determine the amount of asphalt using extraction and recovery methods. Also, the group has been evaluating the performance of recycled asphalt shingles using tests.
Asphalt shingles combine asphalt binder, which acts like a glue that binds together, aggregates - tiny stones.
Daily Mining Gazette/Stacey Ashcraft
Zhangping You, associate professor of transportation engineering and materials at Michigan Technological University, shows some recycled asphalt shingles that he and his graduate students are studying as part of a possible recycling program.
Using two different forms of shingles - scrap left over from manufacturing companies and shingles removed from houses during reconstruction, known as tear-off shingles - You is looking for different ways to keep unwanted shingles out of landfills. Part of the project looks at the possibility of recycling the shingles into hot mix asphalt (HMA) pavements.
"The waste from the manufacturing companies is what we really like to use because left in the shingles, there are over 30 percent of asphalt by mass and that's really high quality materials," he said.
Aggregates, the little rocks seen on shingles, are a higher quality material and are normally better than the aggregates used on the road, he said.
Also shingles contain a high volume of fibers which help hold the shingle material together.
"If we have fibers inside, we can increase some of the performance," he said.
Tear-off shingles can be very old and are commonly dumped in landfills and sometimes, on the sides of the road or in forests, You said.
"It is very expensive to dump those in a landfill per tonnage," he said.
So the composition of asphalt shingles is similar to hot mix asphalt because of mineral fines and aggregates. The fibers serve as a bonus - a way to create a reinforcement for the HMA, he said.
Some of the unwanted aspects include some older shingles and shingles with wood chips.
"The older ... shingles, they age too much," You said. "Under rainfall and especially sunshine, and with oxygen, the asphalt actually becomes very hard."
So far, the project has been yielding ideal results.
You said during the process, asphalt binder was extracted from the asphalt shingle waste and was added to virgin asphalt at the rate of 5 to 6 and up to 10 percent.
Using Superpave binder testing, which tests aspects like stiffness and tension, the results show that asphalt binder containing the shingle waste improve rutting and fatigue resistance, he said.
"In that case, we can save, if not half, at least one-third of new asphalt we are supposed to use," he said.
That will save contractors a significant amount of money by using recycled materials.
The cost of using recycled shingles in HMA can range anywhere from $0.50 to $2.80 per ton depending on the cost of pure asphalt and use of tear-off shingles, he said.
You plans to continue research with the project, where students learn extracting and recovery techniques in the laboratories. As part of the ongoing research in the study, the group evaluates the rheological - or the way which matter, including water, flows - properties of asphalt shingles.
You said he's had the chance to talk to engineers downstate who like the idea but "can't afford a failure," therefore You plans to continue more research to refine the project.
"Just today, my students sent me more results with the project," he said. "That's why we spend more time in the lab."
Stacey Ashcraft can be reached at sashcraft@ mininggazette.com.