Thursday | February 22, 2018

How to Use Stamped Asphalt and Preformed Thermoplastics

Each contractor brings a unique flavor to the job, whether that be the longevity of his staff, a commitment to customer service, the highest job quality using the highest caliber equipment, or a mix of all those factors. No two contractors offer the same secret sauce, but stamping and preformed thermoplastics can add a unique ingredient to your recipe of perfection.

Both stamping and preformed thermoplastics can be used on asphalt jobs for communities and commercial businesses that want some extra curb appeal or need utilitarian markings for clarity.

Stamping is the process of placing and rolling patterned stencips, like brick and stone, on heated asphalt—either new asphalt or reheated existing asphalt—and then rolling your mat. Then, the pattern will be stamped into the asphalt and a contractor can paint the asphalt itself.

Preformed thermoplastics can be placed over existing asphalt and heated to affix.

A Look at Preformed Thermoplastics

Introduced to North America by Flint Trading Inc., now Ennis-Flint, in 1987, preformed thermoplastics offer another decorative option. Ennis-Flint continues to be a leader in this market according to Zina Brooks, marketing and customer support director for Ennis-Flint.

“Preformed thermoplastic have been proven for long-lasting performance, even in cold climates using snow plows,” Brooks said. Ennis-Flint’s preformed thermoplastic products are most often used for decorative crosswalks and traffic calming guidance, but also for streetscape enhancements and beautification, Brooks said.

Ennis-Flint offers a variety of decorative preformed thermoplastic solutions. In the company’s TrafficScapes Portfolio, it has three options for stamped asphalt applications:

  • DuraTherm, which inlays pre-cut patterns into asphalt that has been stamped. First, you must prepare the surface. Then, the asphalt must be heated, the template is applied and stamped, and then you must position DuraTherm into the pattern and heat to fuse with the asphalt. DuraTherm requires custom plastic templates that can be reused.
  • TrafficPatternsXD, which lays a 150 mil sheet of preformed thermoplastic over asphalt and then stamp. To use this product, you must prepare the surface, position the preformed thermoplastic sheets, heat the material and then stamp the material with a pattern grid. TrafficPatternsXD requires wire rope grids that can be reused.
  • TrafficPatternsLT is another alternative. For this product, you must clean your surface, position sheets over previously imprinted asphalt where coating has worn away and then heat the material so molten thermoplastic will flow into the grooves of previously stamped asphalt.

The TrafficScapes line of preformed thermoplastic products must be applied by a TrafficScapes Certified Applicator, of which there are about 75 to 80 nationwide. Brooks recommends contacting Ennis-Flint for more information. Ennis-Flint also offers StreetHeat grids and infrared heaters for application of the TrafficScapes products, as well as for asphalt reheating and stamping prior to applying specialty coatings.

Some of the most popular TrafficScapes patterns include Running Bond, Offset Brick, and Herringbone using traditional brick-like colors. Although there are many standard designs, some companies allow you to send in a digital design to be transferred onto preformed thermoplastic rectangles for you to put together and place on the pavement, according to Krystal Strassman of DRS Limited, an asphalt paving company based in Madison, Wisconsin, and Asphalt Reheat Systems. 

Today, ARS offers both portable and seam heaters. Portable heaters are most often used to fix patches, whereas seam heaters attach to any paver and heat up the seam ahead of the crew to minimize longitudinal joint failure.

ARS’ portable heaters come in four sizes, a 1×4, 2×4, 4×4 and 4×6. All of the heaters are versatile in that the handles and wheels can be switched around to avoid rolling over your finished product and enable crews to work close to buildings. For stamping applications, Krystal recommends the 4×6 size, which could handle a standard crosswalk. Although Krystal’s own paving company, DRS Limited, doesn’t do much stamping and preformed thermoplastics, she has been a resource to other contractors and city engineers who want to use these methods.

In the past, she’s used preformed thermoplastics without stamping, though she said they do hold up better if stamped.

Your Stamp on the Market

Stamping patterns are reusable and are often made of seven wires in a strand, strung into a set of seven strands to make a grid. Although you can use a fabrication shop to weld them back together, Krystal estimates that after four years, the stencils will be crooked and become difficult to lay.

Ensuring a long life for your stencils requires proper maintenance. Krystal says the first step is proper storage. “Don’t leave them out in the elements,” she said. To minimize the opportunity for stencils to be mismanaged, she said they have a truck dedicated to stamped asphalt projects that has all the required tools and can hold all the patterns in one place. She also suggests dispersing the weight evenly if you’re going to hang up your patterns.

Although stamping individualized patterns isn’t as easy as sending in a digital design, it’s still possible. Krystal recalls using stencils to create a Bucky Badger in a crosswalk on the University of Wisconsin-Madison campus.

“We made the grids we had work by putting rubber under areas we didn’t want to get stamped,” Krystal said. “Then we added detail and color with paint after the fact.”

Although Krystal has seen (and done) some impressive decorative stamping and preformed thermoplastics, she doesn’t expect it to be as mainstream as the functional uses until the price comes down. She estimates, on average, that preformed thermoplastics cost $20 per square foot and stamping, $10 per square foot. Use of preformed thermoplastics that also require stamping cost, on average, $25 per square foot.

However, stamping does require repainting, which can even out the cost difference. Krystal has seen the industry steer more towards preformed thermoplastics in recent years.

“Printing looks nice, but sometimes the paint isn’t adequate depending on the volume of traffic,” she said. For this reason, she recommends using preformed thermoplastics in high volume areas and using stamping in low volume areas. “The other aspect is traffic control. If you paint a crosswalk, you have to shut down that intersection in quarters and will need a couple people controlling traffic the whole time.”

For the most part, Krystal said she sees people using preformed thermoplastics and stamping in functional uses.

“They’ll use it in crosswalks to clearly distinguish that from the road, they’ll put highway signs on the road ahead of you in case a semi is blocking the overhead signs,” she said. “It’s another way for people to better understand the road system and be comfortable driving around.”

How to Use Preformed Thermoplastics

1. Think through the project. “Be methodical. Play it out in your head. Once you get started, the clock starts and you want to be ready with everything you need,” Krystal said. “The glue will harden, and the preformed thermoplastic looks the best when it’s done as one, not in patches.”

2. Clean surface.

3. Apply glue.

4. Apply preformed thermoplastic.

5. Set heater over preformed thermoplastic for suggested length of time. Make sure you’ve placed the heater in a way that you can remove it without damaging your completed work.

6. Take it slow to avoid burn marks. “Like a marshmallow, you can get that golden brown color when dealing with white, which is not good.”

7. Allow preformed thermoplastic to cure, undisturbed, for 20 minutes.

8. Clean up and go home!

*For Ennis-Flint product-specific applications, read bullet points within story.

How to Stamp Asphalt

1. Clean surface.

2. Place heater on desired printing area for suggested length of time. “Only heat what you can print right away,” Krystal said. She also suggests using a small enough heater for one person to control to cut down on labor costs.

3. Remove heater and place grid on the area. Use chalk lines or string lines to keep grids aligned. Overlap grids as you go to keep pattern aligned. “We do a rough print with big grids and have a clean-up crew with smaller grids following behind with a torch to heat any smaller areas, as needed, for an aesthetically pleasing job,” Krystal said.

4. Compact as needed until imprint depths are even.

5. Paint. “This can be done on the same day, or a different day,” Krystal said. However, the temperature must be above 50 degrees Fahrenheit, even at night. “If you paint when it’s too cold, you get a white dusting and the paint doesn’t hold up as well.” Krystal also recommends using a paint roller when painting just the borders and sprayer if you’re coating a large surface.

“Have extra spray tips and, if needed, run the paint through a strainer to get any small chunks out that might get clogged,” she said. “When spraying, you want one person mixing paint, one guy spraying and two guys painting with rollers in different directions so the paint is even.”

6. Apply three coats of paint for high-traffic areas and two in residential and low volume areas.

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