All pavements eventually experience wear and fatigue, and some may even experience total failure. Several factors that determine how well your pavement behaves are the original design, quality of construction, vehicle usage, and the maintenance it received.
As your pavement ages and weathers it becomes brittle, cracks, and may develop holes and depressions. Catching these small problems early may help prevent larger and more costly problems later. Many times simple repairs can correct irregularities or stressed areas in your parking lot without getting into a more extensive reconstruction.
It's fairly easy to determine when your parking lot or roadway needs repair. But, without experience in pavement construction and maintenance, it can be difficult to decide just what should be done.
Although the following does not cover every type of pavement problem and/or repair method, this information should give you a good working knowledge of what we call PAVEMENT CPR.
"C" (CAUSE) What made this type of damage happen?
"P" (PROBLEM) What type of damage is this?
"R" (REPAIR) How is this type of damage repaired?
With any kind of pavement damage, it's important to determine what
has caused the problem. Without this information it would be difficult
to properly repair the problems and prevent their recurrence. A careful
inspection of the pavement will determine why it is in its current condition
and what potential problems may be present.
Although there are other types of pavement damage not mentioned here,
the following is meant to be a guide to the most common types of problems
you will find:
Pot Holes
These are small bowl-shaped holes
from which the asphalt surface is
missing.
A weak area in the pavement structure, water infiltration to
the base, poor maintenance, or asphalt material problems can cause
potholes.
Depressions
Depressions are small low areas in the pavement that typically hold
water longer than the remainder of the pavement. These can be caused by
poor construction or from settlement somewhere in the pavement structure.
Raveling
Raveling is a separation of the aggregate (stone) from the pavement
surface, giving it a rough texture. An inferior asphalt mix, age hardening,
lack of proper compaction, or construction of the pavement during bad
weather can all contribute to pavement raveling.
Slippage cracks are crescent shaped tears in the pavement. A surface layer of asphalt that was installed with a poor bond over the lower layer of asphalt is the usual cause of this damage.
is a series of cracks that form a grouping of small pieces resembling an alligator's skin. These are either caused by a pavement structure that isn't sufficient for the weight of the loads using the pavement or by oxidation, which causes a loss of pavement resiliency.
Shrinkage
Cracking
Shrinkage (or block) cracks are interconnected cracks that form groups
of large blocks with cracks that usually intersect each other at right
angles. The asphalt mix losing its flexibility due to age and oxidation
normally causes this type of cracking.
Pavement depressions in the wheel paths are called rutting. When the asphalt pavement is displaced under traffic or an unstable asphalt mix is installed, there is a good likelihood the rutting will occur.
This type of crack occurs in areas that have been resurfaced. The cracks in the original pavement continue to move and eventually reflect upward through the new asphalt layer.
Just as there are many types of pavement problems, there are also many methods of repair available. Knowing what repair methods are correct for your type of problem is the first step. After that you must make certain that the contractor performing the work uses the proper materials and techniques.
The issue of materials is fairly simple. Most of the local suppliers in our area only sell materials that meet the Ohio Department of Transportation specifications. If you see the letters ODOT included on your bid, you can assume that the material is properly designed.
The issue of technique is another matter. It is extremely important to make sure 1) that you are dealing with a reputable contractor, and 2) that the contractor is using the proper repair method. Following are some guidelines that will assist you in resolving your pavement problems:
Skin Patching
This method can be effectively used to repair surface failures such
as depressions, raveling, or potholes. The area to be repaired should
be thoroughly cleaned, dried, and a tack coat of hot liquid asphalt or
emulsion should be applied. Next, the asphalt is installed. It is critical
to the success of the repair that the material is hot, is spread to the
proper elevation, and is compacted using the equipment best suited to
the size of the job. Finally, the patched area should be sealed around
the perimeter with either liquid asphalt, emulsion, or rubberized crack
filler. Filling potholes is slightly different due to the depth of repair,
but should follow the same procedure.
Remove and Replace
Problems
that are more than surface failures will require more extensive repairs.
Removing and replacing the top layer of asphalt can repair slippage cracks,
while removing and replacing the entire thickness of asphalt is the best
way to repair block cracks, alligator cracks, and rutting.When the problem
is severe, or the base is found to be unstable, the removal should continue down to a solid subgrade. With any of these removals, it is important to neatly saw cut the edges of
the area to be patched. This should extend 1' - 2'
Resurface
If
your pavement has little or no obvious base failure, or if you've repaired
your structural problems and are looking for a way to prolong the life
of your pavement, an asphalt overlay can be a cost effective repair. The area should be thoroughly cleaned and any visible vegetation treated
and removed.Then a tack coat should be applied, with a distributor truck
at a rate of .05-.10 gallons per square yard. A surface course of ODOT
#448 asphalt is then installed at the specified thickness, usually a minimum
of 1 1/2". It is recommended that
Paving Fabric
Reflective cracking is quite common with most overlays, as the original
pavement will continue to move and the old cracks will reappear. One widely
accepted method to reduce the incidence of this reflection is the use
of a pavement reinforcement fabric. The additional cost
can be justified by the retardation of the cracking and the water proofing
benefit of the material. The
fabric must be installed by an experienced contractor. Prior to the overlay,
the area receives a heavy tack coat, approximately .25 gallons per square
yard. The fabric is spread either manually or by a mechanical spreader,
depending on size of the area. It is then broomed to assure complete contact
with the tack coat. A good fabric crew will make certain that all wrinkles
or large creases are slit and laid flat. The fabric is then ready to
be paved over.
Preventive maintenance is perhaps the most important gift that you can give to your pavement. This process involves the early detection of problems and the repair of minor defects before they become major headaches. An experienced and qualified pavement maintenance contractor can save you from spending major repair dollars over the life of your pavement.
As your pavement ages, it weathers from the effects of sun, salt, gas, oil spills, and water penetration. With the loss of its original resiliency, the pavement becomes brittle and begins cracking. Proper crack filling will prevent water penetration into the subbase. Sealing will help to slow down the aging process and protect your pavement investment.
Crackfilling
Periodic crack filling with the proper material is critical to prevent
water infiltration and to slow down further pavement damage. Cracks 1/4"
or wider should have any vegetation removed and be cleaned and dried.
This is critical to assure a good bond. The cracks should then be filled
with a hot applied, elastomeric-type crack fill material. There are several methods that can be effectively used to fill cracks.
The most common is the banding technique, which leaves a 2" - 3" wide
band over the crack. The other method involves routing (widening) the
crack to create a reservoir for the material.
Sealing
Your parking lot does not necessarily need to be sealed every year
or every other year. In fact, too much sealer is not good for your pavement.
However, if done timely and correctly, sealing can extend the effective
life of your
pavement. Sealer needs a clean, dry surface for the best results.Oil and grease spots should be pre-treated and/or primed. Either of two common application methods, spray or squeegee, can be used with success. The material must be mixed according to the manufacturers recommendations and should include the proper proportion of sand additive. Your parking lot is an investment, and like any other investment, needs to be managed carefully. Proper maintenance, along with timely repair, should be employed by your pavement maintenance contractor. This will insure that your pavement life is extended as long as possible, as economically as possible.
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