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Driveway sealants

Which products are best for your asphalt driveway



ealcoating an asphalt driveway every three years not only will make it look better, it actually will make it last longer. Sealing shields paving from the sun's ultraviolet rays, which can deteriorate the binder and expose the aggregate. Sealcoating also prevents water and ice from getting into the paving and causing it to crumble. The sealcoating materials and crack-filling products available to doit-yourselfers are not as good as those available to the trade. However, few tradespeople use the best products available, so you can often still do the job better yourself if you use the right materials -- and you'll save up to 65 percent of the cost of professional maintenance. For most of you, choices will be limited to what's available at your local home center or hardware store. Many larger cities have a distributor of asphalt coating products used by contractors. You may be able to purchase these professional-grade sealers and fillers, but remember that contractors buy in bulk. Most pro-grade sealers come in 55-gallon drums, not the 5-gallon buckets you'll find at the home center. If you want to get the top-of-the-line sealer, check with your neighbors about buying enough to seal several driveways at the same time.

Sealer choices include (from left) plain, filled, sanded and airport-grade. Warranties range from one to three years (plain), three to four years (sanded), four to five years (filled) and up to 10 years (airport-grade).

Coal tar vs. asphalt

Most consumer-grade driveway sealers are water-based emulsions containing water, clay fillers, latex, polymers, additives and either coal tar (a byproduct of baking coal to make coke) or asphalt (a byproduct of petroleum refining). Some so-called "asphalt"

emulsions also contain some coal tar. Although significant improvements have been made in asphalt-based sealers in recent years -- the use of polymers and other additives that increase durability and resistance to oil and gas, for example -- coal tar products still are most popular. According to the sealer manufacturers, coal tar sealers are more durable and much more resistant to oil or gasoline penetration than asphalt-based sealers because gasoline and oil are both solvents for asphalt but not for coal tar. Asphalt-based sealcoating products are better for air quality because they do not emit high levels of volatile organic compounds (VOCs) like the petroleum-based products do. They also smell better and are less of a skin irritant.

Judging quality

Both coal tar and asphalt-based products are available in plain or filled-sealer formulas. Filled sealers contain sand or other solids that fill small cracks and holes. According to Rick Noon, technical director at SealMaster, the more solids (asphalt, coal tar, polymers, etc.) in the formula, the better the sealer quality and the more expensive it will be. You'll get what you pay for, and you get more solids in better- or best-grade sealers. Comparing the various additives and solids used by different manufacturers is difficult because the formulas are considered proprietary information. The general rule is that the top-quality sealers will have the greatest amount of solids left on the asphalt after the liquids evaporate and cure.

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The best way to determine quality is by the length of the warranty. The best-grade sealers typically have a fiveto six-year warranty. The better-grade sealers are generally warrantied for three to four years. Plain sealers will carry a warranty of one to three years. Each manufacturer has its specific prorated warranty, which is usually clearly displayed on the label. A fourth category of sealer has been developed within the last five years or so. It's best described as airport-, racetrack- or pavement-grade. This grade of sealer has more durable acrylic polymers and lasts longer than other formulas. Some come with a 10-year warranty.

Cost and coverage

Asphalt sealers are more expensive than coal tar sealers, primarily due to safer environmental factors (lower VOCs) and the technology (polymers, etc.) that must be added to asphaltbased sealer to improve its otherwise poor performance. Low-end sealers range from $5 to $8 for a 5-gallon pail that covers about 400 sf. These are usually just a thin coal taror asphalt-based paint-like coating. Don't expect them to last more than one season. Unsanded or "plain" sealers (the better grade) with heavier solid content range from $8 to $11; the best-grade filled sealers cost about $12 to $15. Heavy-duty or racetrack-grade sealers sell for around $20 for a 5-gallon bucket.

A complete asphalt driveway sealing job includes (from left), crack fillers, sealer, hole patch mix and spot sealer for oil stains. It's best to repair cracks and holes in the fall and then apply sealer in the spring.

Coverage varies between grades. A 5-gallon bucket of low-end sealer covers around 400 sf. The better- and top-grade sealers typically cover 250 to 350 sf, depending on the condition of the driveway.

Crack filler/sealers

It's important to fill cracks and seal expansion joints between asphalt and other surfaces, such as concrete aprons or curbs, to keep water out and prevent erosion of the paving base. Filled sealcoating materials will handle cracks up to 1/8 in. wide. Hot-applied sealers are best for filling cracks from 1/8 to 1/2 in. wide. Pli-Stix driveway crack and joint filler,

made by Dalton Industries, is the only DIY hot-applied product. You press the coiled material into place and heat it with a propane torch (preferably with a flame-spreading tip) or a heat gun until it melts into the crack. Pli-Stix comes in a 1/2-in.-diameter, 30-ft. roll. It can be stretched to fit 1/4-in.-wide cracks or doubled up to fill 1-in. cracks. It also has a lifetime warranty. Most consumer-grade crack sealers are cold-applied asphalt emulsions with varying concentrations of latex and polymers. They are available in pourable jugs for cracks up to 1/8 in. wide, caulking gun cartridges for 1/2-in.-wide cracks, or as trowelable material for wider ones.

Filling cracks is the key to preventing the asphalt and its base from washing away. Pourable crack filler works best in holes up to 1/8 in. wide. Like sealers, it comes in regular and heavy-duty grades.

Dalton's Pli-Stix is the only hot-applied crack filler available to homeowners. Press the rope-style filler into the crack and then heat it with a propane torch until it melts. Pli-Stix comes in 1/2-in. dia. ropes. It can be stretched to fit 1/4-in. cracks or doubled up to fill 1-in. cracks.


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Sealing frequency

Sealer manufacturers and asphalt contractors agree that most asphalt driveways only need to be sealed about every three years. The exception would be in extremely harsh regions, such as the South or desert areas, or when the asphalt turns gray. Graying indicates that the surface is oxidizing and loosing the binder that holds the aggregate in the asphalt. According to sealer manufacturers and engineers at the Asphalt Institute, most driveways do not need filled sealer until they have begun to develop fine cracks. This generally happens after several years. Let new asphalt cure for about a year before sealing, and then use just a plain sealer. If you do like to seal every year to keep your driveway looking new, use budget-priced, unsanded or nonfilled sealers. The drawback to sealing every year is that the sealer can build up and will eventually peel, which also leads to it being tracked indoors. Sealer can permanently stain vinyl flooring even if you remove it promptly. While some brands boast special ingredients to prevent tracking, proper application and curing are key to avoiding problems. Finally, it's best to repair cracks and holes in the fall and let them cure over the winter. Then, come spring, hose off the driveway thoroughly and apply a single coat of sealer. One thin coat of sealer, regardless of the grade, will give you the best results. Multiple coats do not protect any better and actually will cause problems by cracking and peeling.

Sealer manufacturers recommend applying sealer with a wide squeegee for the most uniform coverage. A regular pointed trowel works best for laying in either deep or shallow hole patch.

If a manufacturer rates its crack fillers using a good-better-best scale, get the best quality product if you want it to hold up as long as the sealcoating itself.

Patching and leveling

Cut out potholes and badly damaged areas to the base material and patch them with packaged asphalt mix or, at a somewhat higher cost, special pothole patching material. The specialty material typically is more flexible and easier to use. The patches even work in wet conditions and can be driven on immediately after installation.

The best repair for really alligatored paving is removal and patching. But Gator-Patch by Maintenance Inc. and Gator Pave by SealMaster can stabilize and level badly cracked asphalt without removing it. You apply them like a filled sealer using a pole-mounted squeegee. Wheel depressions from parked vehicles are nuisances because they collect water. To fill them, use a series of 1/4-in.-thick coats of patching material that's intended for repairing alligatored pavement, or choose a preblended patching material recommended for thin-section repairs.

You'll mix the latter with water and spread it from a feathered edge to up to 1 in. thick in 1/4-in. layers.


American Stone Mix (Sakrete) Towson, MD, (800) 445-8250 Armor Manufacturing, Tacoma, WA (800) 846-9125, Dalton Enterprises (Pli-Stix) Cheshire, CT, (800) 851-5606 Gardner Asphalt, Tampa, FL (800) 237-1155 Gibson Homans/Black Jack Twinsburg, OH, (800) 433-7293 Henry Co., Kimberton, PA (800) 598-7663, Maintenance Inc., Wooster, OH (800) 892-6701, Neyra Industries Inc., Cincinnati, OH (800) 543-7077, Quikrete, Atlanta, GA (404) 634-9100, SealMaster Inc., Sandusky, OH (800) 395-7325, UGL, Scranton, PA, (800) 845-5227 Vance Bros., Kansas City, MO (800) 821-8549

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Fill deep holes and asphalt gaps with deep hole patch (left). Fill holes in approximately 1-in. layers, tamping each layer before applying more patch. Depressions from parked vehicles are best repaired with trowelable, shallow hole patch (right). Feather the edge for a secure bond.




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