"Our part of the country had some of the worst curing conditions - temperature, humidity, and rain - we'd experienced in a long time. And that coincided with the time many contractors were getting their first taste of blends," he says. "It is pretty unlikely that we will see similar conditions again this year."
Crenson says additives can be used to enhance some of the properties of sealers, primarily shortening drying time and developing a tougher film membrane to alleviate some of the differences from coal tar sealers.
"Contractors considering additives should be sure to check with the manufacturer of the sealer because one additive might work with one manufacturer's formulation and not in another manufacturer's formulation," Crenson says.
Two different types of blends are available from Western Colloid, which produces asphalt-based sealers. Jeff Luzar, pavement products manager, says Western Colloid also produces two blended products designed to enhance the asphalt sealer's resistance to gasoline and oil. One product is a custom-made asphalt emulsion sealer fortified with up to 10% acrylic latex; the other is a blended product with 90% asphalt and 10% coal tar.
"If you order the custom product you get 10% acrylic latex, but we also produce that product with varying amounts of latex depending on the job it's going to be used on," Luzar says. "We'll often take a look at the pavement beforehand and if it's a rough pavement that gets a lot of traffic we'll recommend the 10%, but often we'll add just 3% to 5% if the pavement is in better shape."
He says the custom product is more expensive, and the higher the percentage of acrylic latex the greater the cost, so Western Colloid hasn't sold a lot of it in any one year.
"But we expect to sell quite a bit more this year as the situation with coal tar becomes more apparent," Luzar says.
He says the asphalt coal tar blend also is not a high-demand product, especially in western markets where coal tar materials are reserved for airports and gas stations, but he says it's a viable product that some contractors like to use.
"We stay at the 10% coal tar because much higher than that you start getting that coal tar smell and the workers start feeling the burn, and we're very sensitive to those issues in this market," Luzar says.
Vance says that when it comes to blends contractors really need to depend on their supplier. "Your supplier is going to have to know what he's doing because blends are a different animal," Vance says. "Coal tar is a known commodity but blends depend on what you're blending."
Sealer using ceramics
At least two other producers are taking a different approach to the sealcoating market, using ceramics with asphalt material to produce what they say is a new and stronger pavement sealer.
Ronnie Blacklidge, president of Blacklidge Emulsions, says the asphalt-based material they produce relies on a technology based on ceramics developed initially for the space industry. He says the technology enables them to emulsify what's known as "hard pen" asphalt, which has most of the gasoline and light-end oils removed.
"The more of the light-ends you extract, the tougher and harder the asphalt becomes," he says. "Until this process was developed no one had been able to emulsify hard pen asphalt."
Blacklidge licensed the technology from and began developing the sealer (and another product, which it refers to as a "trackless tack").
"This sealer has the same characteristics coal tar has, but it doesn't have the normal coal tar problems," Blacklidge says. "It doesn't burn, it doesn't smell, and where you had to wait 8 hours normally to open pavement to traffic for coal tar, you can open pavement up to traffic in two to four hours under the same weather conditions using our product."
He says the material is more fuel resistant than standard asphalt-based sealers and equally resistant as coal tar sealers because "the more light-ends you take out, the tougher it is."
He says depending on weather conditions in a region contractors might want to use a polymer additive to give the material more flexibility.
Another material using ceramics is produced by Raynguard Protective Materials, which also produces a standard asphalt emulsion sealer. The ceramic product, which according to Gordon Rayner, Raynguard vice president, costs about the same as Raynguard's standard asphalt sealer, uses a "carbonyte process" to strengthen the asphalt binder.