2018 Asphalt Repair Guide: Sealcoating, Crack & Pothole Repair
Table of Contents
- Asphalt Repair Overview
- Alligator Cracking
- Longitudinal (aka Linear) Cracking
- Block Cracking
- Transverse Cracking
- Slippage Cracks
- Joint Reflection Cracks
- Edge Cracks
- Patch Failures
- Other Asphalt Repair and Maintenance Issues
- Asphalt Repair: Bottom Line
Asphalt Repair Overview
There are several reasons why asphalt is a fantastic choice for a wide variety of paving jobs. It’s durable, easy to install, environmentally friendly, and not to mention the fact that it’s one of the most inexpensive paving materials on the market.
A properly installed asphalt paving job can provide decades of service but as the old saying goes, nothing lasts forever.
You might start to notice that certain areas of the pavement are beginning to crack, or you could see potholes or other surface irregularities begin to emerge.
Some of these issues may appear gradually over time, while others might take you by surprise. Below are some of the most common asphalt problems to look out for, as well as what your paving contractor can do to help remedy those issues:
This extremely common pavement problem definitely lives up to its name, since once the blacktop has become riddled with these types of cracks, it can begin to look like the scales on an alligator’s back.
There are a number of reasons why this type of structural failure can occur, including weaknesses in the subgrade or subbase, inadequate drainage, an asphalt surface that is too thin, or some combination of all of these factors.
On paved roads, alligator cracking often starts as longitudinal cracks in the wheel path, but over time it can worsen due to increasing traffic.
Since this type of asphalt defect is the result of a structural failure, your paving contractor will more than likely have to perform what is known as a full-depth patch, which is where the pavement and base below will need to be dug out and rebuilt.
Longitudinal (aka Linear) Cracking
In other words, these cracks will typically be parallel to the edges of the road or driveway.
One of the primary culprits of longitudinal cracking is reflective cracking, which are breaks or cracks in the underlying layers of asphalt.
This is due to movement taking place at the point of the original surface crack. Poor joint construction and/or pavement fatigue are additional reasons why longitudinal cracking can develop.
For this type of paving problem, your contractor will more than likely seal up the cracks up to prevent moisture from seeping down into the subbase. This can only work, however, if the cracks measure no more than half an inch deep.
Any deeper and your paving contractor will probably have to remove the cracked layer of pavement entirely, replacing it with a completely new overlay.
You can think of block cracking as how alligator cracking would look if you were to see it at 10x magnification.
Unlike alligator cracking, however, block cracking is not associated with load stresses. Instead, it is typically caused by shrinkage of the blacktop pavement due to problems with the binding agent that is part of the asphalt mix.
When this binding agent cannot expand and contract with fluctuating temperatures, it creates stress within the asphalt that can basically only be resolved by cracking.
Sometimes this happens due to the way the asphalt mixed at the initial installation. If the mix was too dry when it was placed, it can have this type of effect later down the line.
Block cracking can also be caused by using low-quality asphalt binder, or by mixing low penetration asphalt with fine or absorbent aggregates.
To solve this problem, your paving contractor can seal the cracks but only if they’re less than half one-half inch in depth. If they run deeper than that, your paving contractor will probably have to remove the defective layer and replace it with a fresh overlay.
In this regard, they basically run in the opposite direction of longitudinal cracks.
This type of cracking is usually a symptom of problems with reflective cracking under the surface layer.
Transverse cracks are considered to be a type of thermal cracking because they can sometimes stem from the stresses of daily temperature fluctuations, but they can also be the result of unskilled usage of paving equipment during installation.
In addition, there are cases where transverse cracking can result from the structural failure of an underlying subgrade and/or subbase.
Similar to longitudinal and block cracking, for your paving contractor to fix this they will more than likely seal up the crack as long as it measures less than a half-inch in depth. Any more than that, the entire pavement layer will need to be removed and resurfaced with an overlay.
As the name implies, slippage cracks occur when the surface layer basically “slips” over the underlying layers, creating what in effect are “stretch marks” in the asphalt.
A common reason for this lack of adhesion between layers of pavement is the presence of excessive oils, dirt, or other contaminants that basically block the adhesive from taking hold.
As with many other asphalt repair problems, slippage cracks are usually the result of poor installation practices.
Subpar paving contractors will often fail to apply what is known as a “tack coat” between the asphalt layers as they’re being laid down.
Without this key layer of adhesive material (also called “slow-setting emulsion”), it can be difficult for the previous layer to stay in place as a new one is being laid on top of it.
Your paving contractor will typically fix this type of issue by removing any area where the slippage cracks are found, and then replacing the asphalt with a partial or full-depth patch, depending upon the severity of the problem.
Joint Reflection Cracks
Joint reflection cracks can sometimes occur when a flexible paving material such as asphalt is laid over a rigid paving material like concrete.
In this sense, the cracks are simply reflecting the places where the joints are found in the underlying concrete. By definition, joint reflection cracks do not include reflection cracks that emerge in areas that are apart from the location of the underlying pavement joints.
To repair this issue, your paving contractor will normally seal the cracks so that water won’t be able to seep down into the subgrade.
Once again, the cracks cannot be more than half an inch deep for this to be effective. If the cracks are deeper, the cracked layer of pavement will need to be removed and replaced with an overlay.
They often mimic the path that the pavement edge follows so that if you were to cut off the asphalt at the cracks, you would simply have a narrower pavement path.
Edge cracks are often the result of poor drainage, as well as inadequate support at the edge of the pavement. This can happen due to improperly "tamping" (packing down) the asphalt at the time of installation.
Skilled paving contractors will usually tamp the edges of the asphalt at a 45-degree angle to provide the necessary support for the asphalt layer.
Other common causes for edge cracks are heavy plant growth along the edges and/or heavy traffic. Your paving contractor will usually remedy this situation by first removing any vegetation along the edges and addressing any slow or poor drainage issues.
After that, they will seal or fill the cracks to discourage any further crumbling or deterioration. If necessary, your contractor may also need to reconstruct the pavement area to full width to ensure that any lingering support issues are fixed.
You can often see rutting develop on highly trafficked roads or even on driveways from the wear and tear of studded snow tires.
Rutting is basically a shifting of the subgrade or asphalt pavement layers due to consistent traffic, and it is often caused by a lack of pavement thickness. When rutting happens, it can also produce "shearing" which is the uplifting of pavement along the borders of the rut.
It’s very easy to identify ruts after a rainstorm has passed through the area, as they will often be filled with water. On roadways in particular, puddle-filled ruts can be very dangerous as they can cause hydroplaning due to standing water.
Other common causes for rutting are weak asphalt mixes, lack of compaction of the subgrade, subbase or asphalt itself, or even the presence of moisture in the layers beneath the surface.
If the rutting is stabilized or if it is somewhat minor, your paving contractor can simply fill in the rut and overlay it with fresh asphalt. For more severe rutting scenarios, the entire rutted area will need to be removed and replaced with brand new material.
This expansion creates stress on the asphalt layers, resulting in the pavement being pushed upward and sometimes cracking when cars are driven over it.
Upheaval is quite common in colder climates, as ice "lenses" (layers) forming within the subgrade soil beneath the pavement, begin to expand as long as there’s an available supply of moisture on hand.
These ice layers can siphon water from all directions, even as far away as 20 feet from the main location of the ice lens.
Clay or silt soils are typically more susceptible to upheaval due to inferior drainage qualities, while soils that feature a good combination of sand and gravel can stem the flow of water via capillary action.
To fix this type of issue, your paving contractor will normally have to perform a full-depth patch, replacing not only the irregular asphalt layer but also the layers and subgrade beneath it.
It is not uncommon for shoving to develop in sections of asphalt that also have horizontal stresses, such as where one road meets another.
One of the most common reasons for shoving is excess asphalt being used in the installation by inferior paving contractors.
Other common causes of shoving include using asphalt that is too soft, a weak or insufficient granular base, and/or an asphalt mix that contains excessive quantities of fine aggregate. Shoving can also be caused by excessive moisture content in the subgrade.
Your paving contractor will address shoving problems by performing a partial or full-depth patch, depending upon the severity of the problem.
Like ruts, depressions can fill with water (hence the bird bath reference) and if left in disrepair, they can continue to worsen until they turn into an even bigger surface problem.
Depressions are often caused by settlement in the lower layers of the payment, or some other structural failure that has occurred beneath the surface of the blacktop.
We hate to sound like a broken record here, but depressions are yet another problem that can be traced back to poor installation practices.
Without implementing proper asphalt paving techniques, an unskilled or inexperienced paving contractor can set the stage for depressions and other distortions to develop.
To fix depressions, your paving contractor will first of all assess the severity of the problem. If the depression isn’t that bad, it is possible that only an infrared patch or thin surface patch will be needed.
For severe depressions, more than likely your paving contractor will need to remove and replace the problem area entirely.
In a sense, you could actually rename raveling “unraveling” because that’s essentially what the pavement material is doing – it’s continuing to erode away leaving pock marks, chips, chunks, and an overall jagged appearance in its wake.
There are several reasons why raveling occurs, but one of the most common culprits is – you guessed it – poor installation practices. If an inferior asphalt mix was used, or if the binder was of a poor quality, it can negatively affect the durability of the blacktop surface.
Sometimes there are cases where the asphalt repairs themselves will need to be repaired.
This can be due to a number of factors including poor compaction, the quality of the asphalt mix, and/or the quality of the underlying or surrounding pavement.
Unfortunately, in the world of asphalt repair, there are many unscrupulous contractors who would rather cut corners than do a high-quality job in order to boost their bottom line. As you can see, this doesn’t just apply to the initial installation, but to repair work as well.
Fortunately, an experienced paving contractor can remedy the situation by keeping patch failures from rearing their ugly heads again.
Depending upon the severity of the problem, your paving contractor will perform either a partial or full-depth patch to restore the defective area and bring it back up to the required standard.
Almost everyone is familiar with what these are, especially if you’ve accidentally hit one while you were driving.
Potholes typically have sharp or abrupt edges, and they can wreak havoc on tires and/or front end alignments.
They are often the end result of alligator cracking that has been left unattended. When vehicles roll over this type of area enough times, the persistent pressure can begin to knock chunks of pavement out of the affected area, making the conditions ripe for a pothole to develop.
Common factors that contribute to the formation of potholes include substandard asphalt mixture, weak areas in the subgrade or subbase, and/or using low-quality binding agents.
For this type of extreme surface damage, your paving contractor will need to perform a full-depth replacement patch to repair the damaged asphalt.
Other Asphalt Repair and Maintenance Issues
One of the best ways to curtail expensive asphalt repairs is to have your paving contractor perform regular routine maintenance on your blacktop installation which can include sweeping, sealcoating, and crack filling.
Sealcoating in particular is one of the most vital maintenance items to keep at the top of your list, as it will help protect the surface layer of the blacktop from moisture penetration as well as harmful UV rays from the sun.
When this happens, cracking and accelerated deterioration are basically inevitable. Your best bet is to have your paving contractor apply sealcoating to your pavement every 2-4 years for optimal results.
The exact amount of time will ultimately depend on the overall wear and tear of your asphalt surface and the severity of your climate conditions.
Below are some of the most common obstructions that need to be removed in order to apply proper sealcoating:
If you’ve ever seen a parking lot, driveway, or even a tennis court that has been neglected for a long time, you will often observe grass growing through the many cracks that have formed in the asphalt.
Of course, pavement jobs that are in such an extreme state of disrepair are typically the result of months or years of performing little to no maintenance.
The ideal scenario is for your paving contractor to clean out the cracks using a heat lance before sealing them, so that grass or other organic debris will not get a chance to grow.
A heat lance is basically a tool that burns out any vegetation while also evaporating moisture and blowing debris and dirt out of the cracks in the blacktop.
2. Oil Spots:
If left unattended, they will eventually eat away at the surface layer of the blacktop, causing damage and eventual deterioration.
Your paving contractor should thoroughly clean these areas before applying the sealant, which will help protect the blacktop from this type of damage in the future.
3. Tree sap, mud, berry stains, dirt, etc:
These types of natural substances can form a barrier between the sealant and the asphalt if the area is not thoroughly cleaned before application.
Your paving contractor will have all kinds of cleaning tools in their arsenal – from blowers and gas powered brooms to pressure washers and push brooms – to ensure that the asphalt has been sufficiently cleaned before applying any sealcoating.
Asphalt is one of the most durable paving materials on the planet but as you can see, it is far from invincible. The heavy and consistent use over time will eventually take its toll, which means that your pavement will eventually require some type of repair work.
Asphalt Repair: Bottom Line
The best route to go down is consulting with a qualified paving contractor who can assess whatever repair or maintenance needs might be necessary, and then carry them out with top-quality workmanship.
Contact us today to get your pavement installation on the fast road to recovery!
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