Coal Tar Sealer Vs. Asphalt Cutbacks – What is best, and when to use?

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Overview

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There are basically two kinds of sealers: shiny and dull. Sealers that dry shiny are asphalt-based, such as Gilsonite or Blackmac, they are basically a cutback asphalt with a solvent. Gilsonite salesman will tell you that oil base sealant is the best because it penetrates deep into the asphalt to rejuvenate and refurbish it by adding asphalt back into the oxidized surface. Part of this statement is true, these types of sealers can be beneficial in some cases. An asphalt cutback for example may be beneficial when applied to highly oxidized pavement as it will replenish lost oils, basically asphalt that is 20-30 years old. 

However, for newer asphalt cutback sealers may cause problems as it is much too hard and can actually cause the asphalt to become brittle and crack. The sealer’s softening point is 200-210 F. The softening point of asphalt used for paving is 120-130 F. The Gilsonite Salesmen also won’t tell you the solvent dissolves and breaks down the asphalt binder when applied incorrectly.Cutback sealers also wears away within a year and can leave behind damaged and weaker binder, essentially requiring re application every year.

Cutback sealers were very popular 30 years ago, However as coal tar emulsions have improved, environmental concerns have been raised and cutbacks are no longer the best available option. Oil based sealers are bad for the environment, don’t meet Federal Specs, and are outlawed in several states due to high VOC’s. (pollutants) Here’s what pavementpro.org the industry association for asphalt maintenance has to say:

Gilsonite, or North American Asphaltum is a natural, resinous hydrocarbon found in the Uintah Basin in northeastern Utah. Gilsonite in mass is a shiny, black substance similar in appearance to the mineral obsidian. It is brittle and can be easily crushed into a dark brown powder. Some companies manufacture pavement sealers with Gilsonite as a base material. A drawback to these sealers is the necessity of solvents, usually mineral spirits (paint thinner) to dissolve the Gilsonite. Improperly or over-applied these solvents can damage asphalt pavements.

Here’s what the University of Nevada has to say about coal tar:

Based upon it’s historical performance and widespread usage compared to other available products, refined coal tar emulsion remains the most effective and continues to be the preferred pavement sealer throughout the U.S. and Canada. Refined coal tar emulsion gives the unsurpassed wear characteristics and protects the pavement from motor oil, gasoline and other petroleum products.

Pavement Coating Technology Center, Dept of Civil Engineering, University of Nevada, Reno

Here’s a condensed version of this article from the state of NY about oil based sealers.

http://www.dec.ny.gov/hearings/36795.html

DECLINATION TO ISSUE DECLARATORY RULING WITH RESPECT TO 6 NYCRR PART 205

The promulgation of Part 205 was one of several actions undertaken by New York State, in concert with EPA and other States, to control and reduce emissions of ozone precursors such as VOCs so that New York State and States in the Ozone Transport Region. VOCs contribute to the formation of ground-level ozone. Ozone is unhealthy to breathe, especially for people with respiratory diseases and for children and adults who are active outdoors. Even death can result from exposure to excess amounts of ground-level ozone.

Department Staff have been in discussions with Petitioner concerning its LN-11 – Equinox Asphalt Gilsonite Rejuvenator into the proper category for compliance requirements. Petitioner’s letter contained product information for LN-11, describing it as follows:

The LN-11 Equinox Asphalt Gilsonite Rejuvenator functions unlike any other pavement surface coating.… With an obtainable VOC level of 400 grams/liter.

Petitioner’s second issue concerns the application of Part 211 to LN-11, specifically Section 211.4, which prohibits the use of VOCs to liquefy asphalt used for paving from May 2nd through October 15th (the ozone season) Asphalt to which VOCs have been added, such as LN-11, is also known as cutback asphalt… The composition of LN-11 clearly states that LN-11 includes Asphalt CAS 8052-42-4, Solvent (mineral spirits) CAS 64741-41-9, and Gilsonite CAS 12002-43-6. The Solvent (mineral spirits) constitutes a VOC within the meaning of 6 NYCRR 200.1(cg) and is included in LN-11 for the purposes of liquefying the Asphalt so it can be applied to bituminous surfaces. Because LN-11 is an asphalt product which has been liquified with VOCs, its use in paving applications falls squarely within the prohibition in Section 211.4.

According to EPA guidance, cutback asphalts were responsible for copious amounts of VOC emissions nationwide in 1975, estimated at 655,000 metric tons. In most applications, cutback and emulsified asphalt are sprayed directly on the road surface . VOCs evaporate to the atmosphere as the cutback asphalts cure. The VOC in cutback asphalt will range from 20 to 50 percent by volume averaging 35 percent. EPA’s intention was that cutback asphalts would be replaced by emulsified asphalts. Emulsified asphalts have a much lower content of petroleum distillate, and thus significantly lower VOC content. They can be used as a substitute for cutback asphalt and at a lower cost.

The Department estimated that annual VOC emissions in the State could be reduced by as much as 10,800 tons by the adoption of 6 NYCRR 211.4. Since then, the use of cutback asphalt has largely been eliminated in New York State with the widespread availability of low VOC compliant asphalt-based products.

Cutback sealers do not contain sand and can be very slippery:

Arkansas law suit: Use Sand – http://www.pavementpro.org/sandin.htm

Here’s a PA Court Case about how Gilsonite is slippery. Unfortunately, in Pennsylvania there is no liability created by a general slippery condition on the surface of a parking lot because nobody has taken the time to prove it yet.

http://www.lycolaw.org/cases/opinions/2008/Kingsley052108g.pdf

Ask questions:

Most times, contractors won’t tell you what product they’re using – so its important to ask. They have very little equipment overhead as they don’t need big tanks that agitate the product and they use a LOT less product per square foot. They could care less about cracks and their profit margins are very high. 

Conclusion

All sealers have their place, Coal Tar is the industry standard in the US. We import our product as it is relatively new in our area. There are no major manufacturing plants in Canada. Coal tar is used on many commercial parking lots across the US and it is the product of choice for major companies like Penske Truck Rentals, and Sure Shot Dispensing. Coal Tar Sealer is never slippery, lasts much longer, and provides the best protection.