Coal Tar vs Asphalt-Emulsion Sealer in Champaign: Which One?

September 9, 2026

Two sealer chemistries, one Illinois disclosure law, a list of local bans that does not include Champaign, and a decision that depends on what the pavement is used for.

What the two products are

Pavement sealer comes in two families. Coal-tar emulsion is refined coal-tar pitch suspended in water with mineral filler; ASTM D3320 specifies it as a weather-protective, aliphatic-solvent-resistant coating for airports, parking areas and driveways. Asphalt-emulsion sealer is asphalt suspended in water, specified under ASTM D8099 as a protective coating for roadways, parking areas and driveways. Both go down the same way and both are black. The differences are chemistry, regulation and where each is allowed.

A U.S. Geological Survey fact sheet puts the chemistry in one number. Coal-tar-based sealcoat is typically 20 to 35 percent coal-tar pitch, and pitch is 50 percent or more polycyclic aromatic hydrocarbons, or PAHs, by weight. The result is a product with about 1,000 times more PAHs than asphalt-based sealer: on the order of 50,000 milligrams per kilogram against about 50. Coal tar was long the common choice in the central, southern and eastern United States; the rules below have redrawn that map.

What Illinois and its towns have done

Illinois has not banned coal-tar sealer statewide. What it has is the Coal Tar Sealant Disclosure Act, Public Act 102-242, which, per the Illinois Department of Public Health, applies to public schools and districts, licensed day care centers and state agencies. It defines a regulated product as one containing coal tar or a PAH content above 0.1 percent by weight, or 1,000 parts per million, and IDPH advises scheduling such applications for school breaks or weekends because PAH volatilization is greatest right after the sealer goes down.

The outright bans are municipal. IDPH counts at least 16 Illinois municipalities that have banned coal-tar sealants, naming Evanston, South Barrington, Riverwoods and Winnetka, and at least 12 more with government-use restrictions, including McHenry County. Cook County adopted a 1.0 percent PAH limit that took effect in September 2024. Every Illinois entry on the published ban tracker is a Chicago-area suburb, county or agency. Champaign, Urbana, Savoy and Champaign County do not appear on it, so a Champaign homeowner is choosing on merit rather than under a mandate, unless the property is a school or day care. Ordinances change; confirm the current local rule before quoting elsewhere.

Where the PAHs go

Towns act because of what leaves the pavement. USGS describes PAHs moving off sealed pavement by storm runoff, adhesion to tires, wind, foot traffic and volatilization. Friction grinds the cured film into dust that washes into storm inlets or gets tracked indoors. In the USGS work, house dust in residences next to coal-tar-sealed parking lots carried PAH concentrations about 25 times higher than in homes without them, and coal-tar sealcoat accounted for about half of all PAH inputs to the urban lakes studied.

That matters most on lots with heavy turnover, where abrasion is constant, and on any pavement that drains to a storm inlet, which in a flat city like Champaign is nearly all of it.

How they perform on Champaign pavement

On durability, both chemistries work when applied in two thin coats over a clean, crack-filled surface in the right weather, and both fail when sprayed thick and watered down onto dust. Coal tar's specification is written around resistance to aliphatic solvents, the family that includes gasoline and diesel, which is the traditional argument for it on fuel-drip pavement. Asphalt emulsion is the same material as the pavement beneath it.

Champaign's climate does not favor one over the other. The cure window is identical: air at 50 degrees F and rising, pavement at 55 and rising, up to 24 hours before rain, two hours of daylight after the last pass. The freeze-thaw load of 123.5 freeze days a year and the shrink-swell clay underneath are structural problems no surface coating addresses; the sealer changes the surface's resistance to oxidation and water, not the base.

How to decide

Ask for the sealer type on the written scope. A quote for driveway sealcoating or parking lot sealcoating that does not name the chemistry, the number of coats and the crack-filling step is not a scope yet. Price moves with the product and the mix design, and the cost page walks through what actually changes the number.

• School, day care or state property: the Illinois disclosure act applies to coal-tar and high-PAH products, so specify the chemistry in writing and schedule around occupancy.
• Lot in a Chicago-area municipality: check the local ordinance before quoting; at least 16 have banned coal tar and Cook County caps PAH content.
• Residential driveway in Champaign, Urbana, Savoy or Mahomet: no local ban; the decision is about runoff, tracked-in dust, children and pets.
• Fuel-drip pavement such as a fleet yard: the case for coal tar's solvent resistance is strongest here, and a detergent scrub or oil-spot primer under asphalt emulsion is the alternative.
• Either way: two thin coats, cracks filled first, applied above 50 degrees F with a dry day behind it. The chemistry never rescues a bad application.

The Champaign bottom line

There is no rule in Champaign or Urbana that makes the choice for a homeowner today, and there is a state law that makes it for schools and day cares. What does not change with chemistry is the local physics: a coat put down in the September window over filled cracks will outlast a coat put down in a wet May over open ones, whichever family it belongs to. Get a Champaign sealcoating quote that spells out the product, and let the calendar and the cracks decide the rest.

More from the blog

• Sealing a New Driveway in Savoy or Mahomet: When the First Coat Should Go On
• Edge Cracking on Rural Driveways Around Rantoul and Mahomet
• Snow Storage on Commercial Lots: Where Plow Piles Kill Pavement