Asphalt Repairs and Issues
WHAT IN TARNATION
WHERE did that pothole come from? Why does the parking lot look like the surface of the moon? And when was the last time you thought about your asphalt-maintenance program?
Not long ago I was asked to evaluate the paving in a community that had recently spent $80,000 on an asphalt overlay that was already showing signs of reflective cracking. One of the first things I did was ask to see all the bids that had come in for the project. At first, this confused the board members.
The two losing bids were each over $100,000 – quite a bit more than the winning bid, which immediately triggered alarm bells for me. It turned out that both of the losing contractors had proposed milling out the parking lot prior to the overlay, whereas the winning contractor took a shortcut and eliminated the milling. That seemingly small detail set the community up for a fall as soon as the new asphalt was in place. Within seven months, it was left with the same cracking it had sought to repair – and was $80,000 poorer.
It’s funny that we tell people to keep their eyes on the road when they’re driving, because they rarely look at the roadway itself. In fact, probably nobody in your community looks at any of your asphalt surfaces-roads; parking lots, bicycle paths-until potholes, sinkholes, slip-and-fall accidents, or other problems arise. But recognizing your asphalt needs before something happens can help save your community thousands of dollars. Start by educating yourself on proper asphalt maintenance, including the correct terminology.
Oxidation. Asphalt is made up of 93.5 percent rock and sand (known as “aggregate”) and 6.5 percent tars and oil (“binder”), which are mixed and compacted, creating an asphalt surface that is typically called the asphalt “cap.” As asphalt is exposed to weather, irrigation, fluid spills, and traffic, the tars and oils begin to break down, thus loosening their hold on the aggregate. Known as “oxidation,” this process marks the natural deterioration of your pavement.
Raveling. As your pavement oxidizes, it begins to “ravel,” meaning it loosens its hold on the aggregate and starts breaking away. You’ll see signs of raveling near drainage areas, including in your gutters, and you’ll also be able to feel them underfoot. When your pavement begins to oxidize, it’s time to begin a customized asphalt program that makes your maintenance dollars work for you.
Bases. First, it’s important to determine the type of base material in your roadways and parking areas. In most parts of the country, bases are constructed using granite, river rock, or whatever is readily available. But in Florida, for example, two materials are most commonly used: soil cement and lime rock. Soil cement is mostly used for areas that have a high water table. These bases are designed to “float” as the water table rises and settles, and have a very distinct characteristic-as the surface oils evaporate and dry out, your asphalt will crack in a checkerboard or quilt pattern. Lime rock, which is more stable, is used in areas without lakes or high water tables. Cracking can and does occur with lime rock, but it’s usually more related to stress cracking as the pavement dries out or to some external problem, such as tree-root or vegetation damage. If a lime-rock base is used in a low-lying area, the results are devastating and will be quite costly to repair. Because these two bases react differently to oxidation, it is especially important to know what you’re dealing with before you undertake any maintenance.
Once you’ve established your base material, take note of any problem areas that need attention immediately, such as potholes, cracking to the base, trip hazards, and “alligatoring,” all of which can become quite costly if left unattended. Then you’re ready to figure out the extent of the work you need.
The products and processes you choose should be determined by how badly your pavement has deteriorated. Repairs can range from small potholes to washout areas to sinkholes, and are usually best treated upon discovery. Since there are so many types of repairs, it’s hard to go into detail about all of them, but the basics are almost always the same.
Sawcutting. The best repair method is always to “sawcut” out the defective asphalt one foot away from the edge of the damage, remove all debris, and stabilize the base. (Sawcutting involves using a concrete saw to cut a clean line around the area of repair.) Apply liquid tack coat-tack oil-to the surrounding edges, install hot-mix asphalt, and compact it to the proper density, so it’s flush with the existing pavement.
Milling. Repairs involving raveled or low areas might necessitate “milling” out-grinding away-the defective area. Again, remove all debris and apply tack coat, then install hot-mix asphalt and compact it to the proper density. If you don’t perform milling when you’re installing a complete asphalt overlay of one to one-and-ahalf inches, you’ll end up with a lip along the edges of the repair, which eventually will start to ravel. This is because milling out the old asphalt will allow the new asphalt cap to sit flush with the existing area, while simply installing a one-inch lift atop the old pavement will cause the edges to be elevated one inch higher than any sidewalks, gutters, and so on. Once traffic starts driving over these areas, the weight of vehicles will cause the new asphalt to thin along the edges, become brittle, and eventually crumble.
Overlays. The most thorough repair process is “overlaying,” in which a contractor applies tack oil and installs hot-mix asphalt directly on top of the existing pavement. Make sure to ask your contractor whether they recommend that your existing asphalt be milled out prior to installing the asphalt cap, to help prevent reflective cracking. Along those lines, if your pavement has severe, deep cracking, more than likely a contractor should include a crack sealant or milling in the price prior to a new asphalt cap being installed.
Investigation. If you’re experiencing dips or sunken areas in your roadways or parking lots but aren’t ready to spend the money for a full-blown search-and-discover effort, one quick, cost-effective solution is to apply hot-mix asphalt to the problem area, compact it to the proper density, and see what happens. If the asphalt begins sinking rapidly within a few weeks of the repair, you’ll have to bring in an underground specialist to explore the area further. If the area doesn’t sink, the problem may have just been a “void” underground, and the repair should remain stable. Voids can be the result of a rotted tree root, water pocket, washout area, shifting underground stones, or, worst of all, a sink area. To figure out how to proceed, look around the area of the void for any sewers, sewer covers, or other drainage areas that suggest the presence of a cracked pipe, which might be leaking water and destabilizing the pavement.
If your community is fairly well established, it may have already begun an asphalt-maintenance program using either “sealcoating” or “rejuvenation.” Reviewing your records will help you determine which type of program has already been started.
Sealcoating. Asphalt sealcoating is a water-based, coal-tar emulsion that coats the surface of your pavement, lending it a black appearance and providing minimal protection from oxidation. Because it’s water-based, it has no way to actually penetrate or adhere to your pavement, meaning you need to reapply it every 12 to 24 months. What’s more, within weeks of being applied, the sealcoating will begin to “delaminate,” or peel up, leaving your travel and turn lanes uncoated and the edges dark. Eventually the areas where the sealcoating is still present will begin to crack due to the asphalt and sealcoating expanding and contracting at different temperatures. Through repeated applications, the cracks will become larger and larger, until eventually the pavement will need a complete overlay.
Sealcoating has served our marketplace as well as could be expected, especially considering that, until the 1980s, it was the only process available. Indeed, the original concept-to cover or coat the underlying surface and protect it from the given environment-was an inexpensive way to improve curb appeal. But once the pavement is exposed to weather and traffic, the inherent flaking, chipping, and peeling make sealcoating valuable only for as long as it’s in place. Plus, over time, people become addicted to the uniformity of its aesthetic properties, overlooking the repeated costs of having to apply it every two years and the long-term liability it imposes by accelerating deterioration of the asphalt cap.
Rejuvenation. A more modern alternative can be found in tar-based rejuvenators, which are designed to replenish tar oils that have been lost due to oxidation, thereby reconditioning your pavement and allowing it to adjust to ever-changing conditions. Because rejuvenators are made of the same products as your pavement, they penetrate the asphalt surface. And, unlike sealcoatings, they don’t delaminate but rather oxidize in the same capacity that new asphalt does. That means rejuvenation reconditions your asphalt, giving it back the flexibility it needs to expand and contract-as the weather dictates-without cracking.
Generally you want to perform rejuvenation every three years, although there have been properties that have gone five to seven years between treatments. Because each application extends the life of your pavement by such a significant margin, incorporating rejuvenation into your maintenance program can help you extend the life of your pavement indefinitely.
Choosing one. If your property has not begun an asphalt-maintenance program and has untreated virgin asphalt, you can begin a sealcoating or rejuvenation program. However, if you’ve already started a sealcoat program, you must continue with it until an entirely new overlay has been installed. Oil and water, as it were, don’t mix-rejuvenators can’t penetrate the sealcoating and asphalt, and instead would leave a tarry, sticky mess on the surface. Thus, even though sealcoating provides minimal protection to begin with, it’s best to reapply it when you can see down into the cracks, because protecting your base is vital.
If you’ve already begun a rejuvenation program, then you’re on the right track and should check with your contractor about what the manufacturer recommends for application. You can apply sealcoating on top of rejuvenation, but why would you? Yes, sealcoating is less expensive. But the problems that sealcoating causes and the frequency of applying it-along with the cost of the overlay that sealcoating necessitates-far surpass the expenses associated with rejuvenation.
GETTING IT DONE
Now that you have grounding in the basics of asphalt maintenance, you’re ready to get to work. At this point, two things are important: Making sure your maintenance records are in order, and finding a contractor with whom you work well.
Keep good records. Because board members and managers change, it’s important to set up an asphalt-maintenance file. Include such information as a property overview map, total square yards of paved surfaces, records of any previous maintenance work, signs and striping details, and anything else that might pertain to your parking lots and roadways. (See “The Asphalt Files,” below.)
Find a contractor. Any contractor you select should be fully licensed and insured. Make sure you choose a firm that does its own work. Otherwise a company may act as a contractor, then subcontract all the work to other companies and tack on a 10 to 15 percent profit for itself-similar to a finder’s fee. One of the potential downsides to this is the company might subcontract to a firm with whom you’ve had problems in the past, or that isn’t insured or qualified to do the work you need.
During the bidding process, tell your contractors exactly what you want. If you need specific repairs-say, a surface coating and striping-give all your bidders the same information. If one of the contractors discovers additional issues on-site, make it a point to notify the other bidders that changes have been made. It’s impossible to compare apples to apples when someone brings you an orange.
If one contractor’s bid is much higher than the others, ask why. Or, try something different-rather than ask the highest contractor why they’re so expensive; ask the lowest bidder why they’re so cheap. This might reveal a process or shortcut with which you’re not comfortable. Certainly the community mentioned in our introduction could have benefited from this tactic.
Likewise, it’s a warning sign if a problem is serious and the other contractors make no reference of it. Of course, you also have to allow for honest, professional differences of opinion.
For example, if one contractor states you need to mill out to the base and another one doesn’t, ask for additional information from both of them, and ask them to back it up in writing. The company that won’t back it up in writing is the one to avoid.
Lastly, look for a contractor that’s attentive to your needs. Many times I ask my customers about garbage pickup days, disabled residents in the community, special events that might be held at their clubhouses, and so on, and they always seem surprised by my questions. But these are all important things to know when scheduling asphalt maintenance to make sure everyone in the community is well-informed.
And information is what this is all about. Educating yourself about asphalt and the proper way to maintain it can help you transform your pavement from an expense to an investment. As you map out your asphalt-maintenance program, you’ll be on your way to saving thousands of dollars over the lives of your parking lots and roads. Remember-the euphoria of a low price is nothing compared to the hangover of a poor quality job.
CONNIE LORENZ is president of Asphalt Restoration Technology, in Orlando, Florida.
COMMON GROUND magazine September-October 2005Share