PM Program Keeps Asphalt Parking Lots Up-To-Speed

Drive through your parking lot and view it through the eyes of a customer, visitor, or employee.


Drive through your parking lot and view it through the eyes of a customer, visitor, or employee. What is the initial impression? Is the lot smooth, clean, and well maintained? Or is the surface bumpy, cracked, and riddled with tire-grabbing, ankle-turning potholes? Are the stripes and arrows clearly visible, or faded and hard to decipher?

As the television commercial wisely said, "You only get one chance to make a first impression." Potential customers and employees often form a positive or negative impression of your business just by driving through the parking lot. A well-maintained parking lot presents the business at its best by conveying quality, professionalism, and pride.

If driving through the lot resembles a roller coaster ride, a flat tire or bad impression could be the least of your worries. If someone trips in a pothole or catches a heel in a pavement crack and falls, a large liability suit is probably on the horizon.

And if appearance and liability aren't good enough reasons to practice regular maintenance, there is another very significant factor. The parking lot is one of the plant's major capital investments, and maintaining it properly saves significant long-term dollars.

Anatomy of a pothole

Asphalt parking lots are built in layers: earth on the bottom (subbase), stone in the middle (base), and hot mix asphalt on top. The top surface is made of liquid asphalt (glue) and aggregate (stones). Liquid asphalt holds the aggregate together and provides a solid surface for traffic.

As the sun beats down on the unprotected black surface, liquid asphalt eventually evaporates, allowing the stones to break loose and wash away. In addition, as asphalt ages, small cracks develop, allowing air and water to penetrate beneath the surface. As these elements work their way down to the lower levels, particularly the bottom layer of earth, the pavement becomes less solid. Passing traffic pushes down on the softer area, forcing the base material out the cracks. Eventually, a small depression is created on the surface, and as the layers give way, a pothole is born.

The problem is most acute in winter, particularly areas where the temperature alternately rises above 32 F and then falls below, creating highly destructive freeze-thaw cycles. The freeze-thaw cycle begins with just a tiny crack. Water seeps in and travels down to the stone and earth layers.

When temperatures drop below freezing, the water-soaked ground freezes and expands. This action forces the stone layer up into the asphalt and widens the crack further. Then, when temperatures rise, ice thaws and the earth base and stone subbase contract, leaving an air pocket beneath the asphalt.

Each time the cycle repeats, the crack and space beneath the surface enlarge. Eventually, traffic crushes the unsupported asphalt, creating a pothole.

If you wait for spring before repairing the problem, the freeze-thaw cycle keeps repeating, working away at the sides and bottom of the hole. Water, ice, and snow collect in the pothole and seep into the surrounding subbase. An ever-enlarging area of the parking lot is destroyed.

Establish a PM program

If your lot contains any of the problems noted in the "Take a walk" section, correct them immediately -- regardless of season -- before the damage gets worse and more costly to fix. Then initiate a year-round maintenance program to keep the lot in good shape.

Find a reputable contractor to do the work through personal knowledge or referrals. Visit the sites of the contractor's work and examine its quality.

When the contractor comes to your plant, walk through the lot and discuss the problems. If you don't know much about asphalt repair, ask questions and get educated. It is your money wearing away in a bad lot.

Find out what kind of warranty comes with the work, how long the job will take, and what kind of materials will be used. If you request bids from multiple contractors -- which is advisable -- define the parameters of the job so cost comparisons are possible. Identify the services needed and specific areas to be repaired.

Once the parking lot is up to par, keep it that way with a regular maintenance program. A long-term, systematic PM plan of 2 to 5 yr allows budgeting of necessary repairs, money for regular upkeep, and greater overall control of parking lot expenses.

Resurface every 15 to 25 yr, if a regular PM program is in place. This interval is about the time it takes for asphalt to erode to about half its original thickness. Without preventive maintenance, 7 to 10 yr between resurfacing is the norm.

Cracksealing is the first step in preventing potholes. Fill all openings 1/4-in. wide or larger with a hot pour material. Be sure the cracks are cleaned and dry prior to applying the material. Cracksealing should be done on an as-needed basis.

Sealcoat every 2 to 4 yr, depending on traffic volume and condition and pavement porosity. Sealcoating protects the surface by preventing the sun's rays from drying out the oils in the asphalt. The procedure also seals hairline cracks that eventually lead to potholes, and protects the pavement from petroleum decay caused by car oil.

Sealcoat in warm weather. For example, in the Midwest, the work is done between May and September when temperatures are above 50 F. Paving is performed from April through November. Potholes and cracks should be filled as they occur, regardless of the season, to prevent problems from growing.

Remark after paving and sealcoating. If sealcoating, paint again after 60 days in order to brighten the stripes and build up the thickness. Occasionally, as a result of chemical incompatibilities between sealer and paint, the new color fades almost immediately after application. Check for other paint possibilities in this case.

Quality materials and installation are critical to long-term success. Material cost is a minor percentage compared to labor, equipment, and overhead expenses.

-- Edited by Ron Holzhauer, Managing Editor, 847-390-2668,

Key concepts

The parking lot provides the company's first impression for all visitors and customers.

Repair all potholes and cracks immediately to minimize future problems and lower costs.

After the parking lot is returned to top shape, initiate a year-round maintenance routine to keep it that way.

Year-round job

Regardless of plant location, parking lot maintenance requires 12-month attention.

January-February -- Repair potholes and large cracks as they appear.

March-April -- Solicit bids for maintenance, including asphalt and concrete repair, sealcoating, catch basin repair, bumper blocks, and lot marking.

April-May -- Install hot asphalt over the surface as soon as weather permits. Sealcoat once temperature holds 50 F for at least 24 hr.

June-August -- All phases of maintenance can be performed.

September-October -- Schedule and complete all remaining work before arrival of cold weather.

November-December -- Solicit bids for next year's work to get on the contractor's early schedule and possibly avoid price increases.

Take a walk

Even if you know next to nothing about paving, you can evaluate the state of the parking lot with a simple walk through, which is best done in warm weather. Be alert for several culprits.

Unsealed cracks. Fissures are a pothole in the making. Seal them with hot pour crack sealer before winter.

Spider webbed or alligator cracks. Replace cracks before they become hazards.

Depressions. Look for puddles of standing water after a rain. The depressions are prevalent where car tires continually rest. They are early-stage potholes that must be fixed.

Worn away sealer . If the sealer is gone, or the lot is over 1-yr old and never been redone, sealcoat the pavement with a high-quality product. Plan to do the work between May and September, since sealcoating requires warm temperatures.

Poor parking lot markings . If the lines are not bright and clearly visible, it's time for repainting.

Insufficient handicapped parking . Make sure your lot is in compliance with local ordinances and federal regulations.

More info

The author is willing to answer technical questions about this article. Mr. Rose is available at, website: www.rosepaving. com.

Texts of recent Plant Engineering articles can be found on our website, www. Copies of articles may be purchased by calling 847-390-2692.

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