Paving Fabric Goes Green

By Lisa Cleaver

Paving fabrics have been long recognized as a way to help pavements last longer. According to AASHTO, the number one cause of pavement deterioration is water intrusion through the pavement. In addition to providing an effective moisture barrier for pavement, paving fabrics can reduce the need for repetitive maintenance and rehabilitation costs over time. The key benefits are reduced crack development and limited water intrusion.

Paving fabrics are typically a nonwoven, polypropylene fabric used as a water-proofing membrane. Applied with and in combination with a liquid asphalt tack coat, this system can be used under AC overlays and under chip seals.

Although paving fabrics have been around since the mid-1960s, like many other technologies these days, they are getting greener. TenCate Geosynthetics now offers a paving fabric created with post-consumer throw-away plastic containers. This “green” paving fabric is still manufactured with polypropylene, however, it’s blended with waste polyester, which is obtained from the recycled plastic bottles.

“The green paving fabrics meet AASHTO specifications for conventional paving fabrics, including installation,” says Mike Samueloff, engineer – pavement solutions with TenCate. “The installation process for green paving fabric is the same for a conventional paving fabric.”

Kevin McGrath, president of American Paving Fabrics, based in Hanover, MD, agrees, noting that his company recently used the green paving fabric on a parking lot project and there was nothing extraordinary about the installation process. “Same equipment, same process,” he says.

A more effective moisture barrier

The parking lot was located in Baltimore, MD at an industrial warehouse facility and had extensive reflective cracking throughout. It was suggested to the parking lot owners that a paving fabric would help mitigate the cracking. Nearly 20,000 square yards of the green fabric was installed over the surface area.

“The owners really like the fact that this particular fabric was green,” says McGrath. The TenCate fabric is manufactured with up to 25 percent post-consumer plastic waste. One difference between this fabric and conventional fabric, says McGrath, is that the fabric is a little heavier. This has both benefits and disadvantages.

“Because the fabric is a little heavier, we noticed the standard rate of AC, which is normally .25/gallon, went up to .27/gallon or .28/gallon,” he says. “On this project, we used a PG 64-22 grade asphalt at 315 degrees F. But the benefit of the paving fabric being heavier is there is more ‘meat’ in place fighting the moisture penetration that happens with asphalt.”

Green paving fabrics have an advantage over conventional paving fabrics because of its construction from plastic resin, says Samueloff. “Green paving fabrics are expected to have a higher effectiveness as a waterproofing barrier because of its increased amount of PG asphalt binder applied during placement,” he explains.

Samueloff also notes that this green stress-absorbing membrane interlayer (SAMI) can be used any where there’s asphalt paving – from roads to airports to parking lots. The fabric is manufactured to meet AASHTO M288 paving fabric specifications and meets all the tensile and physical properties necessary.

“This fabric can be milled up and used in RAP; it will go through the screening process, just like any other paving fabric,” he explains. “We also offer a two-year guarantee on the product, for an extra sense of security.”

American Paving Fabrics, which serves the Mid-Atlantic Region and uses fully computerized distributors and state-of-the-art lay down units, has been installing paving fabrics for 15 years. The company has up to 10 paving fabric crews operating at a time, says McGrath. “We’ve had a lot of experience with laying down paving fabric,” he says. “We’re very happy with the new green paving fabric. The installation procedure went well on this job; the paving contractor was happy. We couldn’t ask for more.”

For more information, contact Mike Samueloff at TenCate: e-mail, m.samueloff@tencate.com, or call 248-250-7714.

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