By Garrett Simmons
On a humid Wednesday morning the last week of July, crews inside the asphalt plant on Poplar Tent Road are starting up another 10-hour workday. Movement on the ground is steady, the atmosphere calm despite the commotion of processing machinery and the rumble of trucks pulling into and out of the plant’s gated service entrance. For the last three months, this and five other Blythe-owned facilities in the Charlotte area have been busily chugging away, supplying paving crews throughout the region with the material needed to stay ahead of the packed summer schedule.
At first glance, the scene appears to be just like any other asphalt plant in the country. But in a remote corner of the site, concealed by mounds of unprocessed stone and reclaimed road material, Blythe Construction technicians have been quietly but determinedly creating a product that is leading the way of the paving industry.
Meet Recyflex: a highly durable, cold-mixed base material for new roads. It has twice the bearing capacity of conventional products, thereby reducing a typical 16-inch subbase by half, and has been shown to both increase drainage and reduce frost penetration when compared with existing products. Simply put, it’s a game changer. And if Recyflex represents the future of asphalt technology, as leaders at Blythe Construction, Inc. believe it does, then it’s worth mentioning that it is also changing how we look at the past.
That’s because Recyflex is literally made of material from roads that were once driven every day. In fact, 50 percent of every batch consists of reclaimed asphalt product, or RAP, gathered from old, worn out, or damaged roads around Charlotte. Meaning that for every resurfacing project that Blythe takes on today, the company gains material for building new roads in the future. As plant Manager Steve Nearhood explains, this marks a major step toward sustainability in an industry not known for being environmentally conscious.
Any time you’re able to reuse old material, you reduce the amount of stone you take out of the earth,” he says. “This cuts down the cost of building new roads, and reduces the environmental impact as well.
With Recyflex, we’re taking less new material from the ground, plus getting rid of waste that already exists from previous jobs. And because it’s stronger than conventional products, we’re able to use smaller total amounts of Recyflex than a typical subbase.”
In fact, recycling has long been a standard practice within the asphalt industry, according to Nearhood. What makes Recyflex significant is just how far advanced it is beyond other renewable practices. “Recycling old asphalt has gone on for 30 years or more,” Nearhood says. “Just not at this level.”
Nor in quite the same way, according to Allen Hendricks, Vice President of Asphalt at Blythe Construction, Inc. Hendricks played a central role, as a member of Blythe’s asphalt technology committee, in introducing Recyflex to the company’s operations. Prior to its development, he says, Blythe was able to reuse only about 30 percent of all RAP taken from resurfacing jobs, and even that could only be used for hot-mix surface coating, not for subbase material. “The remaining 70 percent just piled up at our plants,” he says. “We’re always searching for creative ways to reuse old materials. With Recyflex, we recognized the potential to use all of the leftover RAP we needed for subbase material on new roads.”
Hendricks recalls first learning about Recyflex in the mid-2000s, when Blythe Construction’s parent company, Eurovia (VINCI), introduced the technology at an international construction industry meeting. The product, which was designed and patented by Eurovia, was unusual in that it was made using a cold-mix method, rather than the standard hot-mix process requiring Fahrenheit temperatures of greater than 300 degrees. Also unique were the ingredients used to make it. Recyflex breaks down to approximately 50 percent recycled RAP, 50 percent Aggregate Base Course (ABC) stone from a quarry, 2.5 percent emulsion for binding, and 1 percent cement. Not only were the ingredients and production process highly unconventional, research and test results actually showed increased performance over conventional paving methods. Recyflex at that time had already been used outside of the United States, on runways at the Montreal airport in Quebec, and was proving to be a formidable product.
Impressed by what he saw, and eager to test Recyflex in the US, Hendricks included it in a 2007 contract proposal for the NCDOT. Unheard of and unproven in the States, Recyflex was ultimately cut from the project by NCDOT in lieu of further testing. In response, Blythe commissioned a study by the National Center for Asphalt Technology (NCAT) the following year, which would examine the durability of Recyflex under realistic conditions. Results of the study persuaded NCDOT to allow Blythe to use the material in 2008 on a temporary road that was part of the I-485 outer loop project—about 3,000 tons of recycled material altogether. Hendricks invited NCDOT to perform onsite tests on sections paved both with Recyflex and with conventional methods, using an instrument known as a “falling weight deflectometer”. Again, the results were overwhelmingly positive.
“The tests actually showed the Recyflex to be more durable than the section using conventional methods,” Hendricks says. The temporary road was in place two years, servicing high volumes of car and truck traffic, and “performed beautifully,” he says. “The Recyflex held up under heavy conditions without any issues whatsoever.”
Introducing new paving technology is an incremental, and occasionally slow, process. Following the completion of I-485 and demolition of the temporary road made with Recyflex, at least two years passed before Blythe was able, in 2013, to incorporate it into another major bid proposal. That year, the NCDOT awarded Blythe with a major I-85 corridor expansion contract. Recyflex was approved for use on all shoulders, for a total of 16 miles and more than 50,000 tons of material. That’s more than 25,000 tons of RAP that would have otherwise continued to sit, taking up space in the asphalt plant, which is now being recycled instead.
Recyflex Production at 1,200 tons per day
With the expansion of I-85 well underway this summer, Nearhood and his team are producing 1,200 tons per day of Recyflex, all of it on-site at the Poplar Tent Road facility, at a rate of approximately 200 tons per hour.
To accommodate this schedule, Blythe has installed a new silo to store one of Recyflex’s key ingredients, cement. Another key ingredient, CSS-1h emulsion, is produced at a separate Blythe facility and delivered in tankers to the site. At the base of the silo, crews have set up a portable processing machine called a “pug mill”, on loan from Blythe’s sister company, Hubbard Construction, in Florida. Four workers—one operator, one ground person, and two loaders—are required to mix the four ingredients that make up Recyflex and load the final product into the delivery trucks. Nearhood explains that once it’s loaded, the Recyflex must be taken directly to the jobsite where it is being used.
“Having cement as an ingredient shortens the lifespan of the material, because it will set.” He says the quickened timeline is possibly the only downside he has observed in Recyflex. “Because of its nature, we can’t produce large quantities at one time and store it for later. It must be made to order, at very close to the rate it’s being applied.”
Otherwise, says Nearhood, the process of making it is similar to most other conventional paving materials. “We did some initial training, going over how to operate the machine properly and ensure safety. We’ve had no issues at all so far. Overall it’s been a smooth process from the start.”
As of now, Nearhood and his crew members have produced and loaded approximately 30,000 tons of the total contracted amount. That’s more than half of all the Recyflex material that will leave the Poplar Tent Road facility this summer to be delivered to I-85. While there are currently no other scheduled projects that include Recyflex, for Nearhood there is little question of its continued use in the future. “This is the leading edge of the paving industry,” he says. “That’s exactly where we enjoy being, and where Blythe has always been. Out in front, showing the way.”