Asphalt’s durability and value for money make it a popular choice for parking lots, driveways, and roads. However, weather, aging, lack of maintenance, high traffic load, or even poor site preparation may all lead to issues from time to time.
Here we look at some of the more common asphalt paving issues, their causes and how to fix them.
The Best Defense is a Good Offense
You can extend the life of your asphalt pavement by performing regular preventative maintenance. These measures include keeping the surface free of debris, sealcoating, and repairing as soon as you notice them. But before you can fix an issue with asphalt pavement, you need to know what they are.
Here are eight common asphalt paving issues, their causes, and how you can fix them.
1. Raveling
Figure 1. An example of raveling. Raveling is the breakdown of asphalt as particles dislodge from the surface. This breakdown results in uneven surfaces and accumulation of loose debris and standing water.
Have you ever walked through a parking lot and noticed loose gravel and grit? If so, you have likely seen raveling first hand. Raveling is the breakdown of pavement by the loss of asphalt and rocks.
Over time, the pavement thickness decreases and loose gravel abrades the remaining asphalt. Once gravel has penetrated the asphalt, water seeps in and make the problem even worse. Raveling can leave you with an uneven surface (trip hazard!) and standing water.
How to fix raveling in asphalt
The first step in repairing raveled asphalt surface is to remove all loose material.
- If the raveling is limited to a small area, apply a simple asphalt patch.
- If you have, large raveled areas of pavement, this suggests general asphalt failure. When this happens, the best long-term strategy is to remove the damaged pavement then overlay with fresh asphalt. This will require the services of an asphalt professional.
2. Depressions
Figure 2. A water filled depression. Depressions in asphalt are usually caused by poor compaction during the paving process.
Depressions are low areas of pavement that do not penetrate the asphalt and they are typically caused by poor compaction during the paving process.
If not fixed quickly, the water and debris that typically collect in depressions can wear on the asphalt surface and weaken its integrity.
How to fix depressions in asphalt
- A temporary fix for minor depressions is a simple asphalt patch on top of the existing pavement. However, patching will not solve the underlying problem of poor compaction so the affected area may continue to sink.
- Permanent repair of asphalt depressions requires that the affected area be removed, the poor sub-grade be replaced, and a full-depth patch be applied over the repaired sub-grade.
3. Potholes
Figure 3. Potholes in asphalt pavement are often due to changes in weather, standing water or an influx of heavy traffic.
Potholes are small, bowl-shaped depressions in the pavement surface that penetrate all the way through the asphalt layer down to the base course. The edges of the potholes can be quite sharp and potholes in asphalt pavement will increase in size over time as moisture infiltrates the affected area.
Potholes in asphalt are typically the end result of alligator cracking (also known as fatigue cracking.) As alligator cracking becomes severe, the interconnected cracks create chunks of pavement, which can be dislodged as vehicles drive over them. A pothole is what we call the hole that is left after the pavement chunk is dislodged.
These notorious safety hazards are one of the most common pavement defects. The depth of the pothole and the roughness of its edges can cause serious damage to vehicles and can be a trip hazard to pedestrian traffic.
How to fix potholes in asphalt
There are multiple ways to fix potholes. Below, we describe two common methods.
Throw-and-roll [1]
- Place the patching material into the pothole without any preparation or water/debris removal.
- Compact the patching material using the patching truck tires (usually 4 to 8 passes).
- Check the compacted patch for a slight crown. If a depression is present add more patching material and compact.
Semi-Permanent Pothole Patch [1]
- Remove water and debris from the pothole.
- Square up the pothole sides so they are vertical and have intact pavement on all sides.
- Place the patching material into the clean squared-up hole. The material should mound in the center and taper down to the edges so that it meets flush with the surrounding pavement edges.
- Compact the patching material using a vibratory plate compactor or a single-drum vibratory roller. Start compacting in the center and work out toward the edges and check that the compacted patching material has a slight crown. This is done so that subsequent traffic loading will compact it down to the surrounding pavement height.
[1] Federal Highway Administration (FHWA). (June 1998). Long-Term Monitoring of Pavement Maintenance Materials Test Sites, Publication No. FHWA-RD-98-073. Office of Engineering Research and Development, Federal Highway Administration. McLean, VA.
4. Alligator Cracking
Figure 4. Alligator cracking is caused by structural failures in the asphalt combined with continuous heavy traffic.
Fatigue cracking (a.k.a. alligator cracking) is one of the most common ways that asphalt pavement can deteriorate over time. It gets its name from the distinctive cracking patterns that resemble the scales on an alligator’s back.
Alligator cracking is a type of load-related deterioration resulting from:
- a weakened base course or sub-grade,
- too little pavement thickness,
- overloading, or
- a combination of these factors
Once alligator cracks form, the pavement will continue to deteriorate unless you take action.
How to fix alligator cracking in asphalt
- A short term fix is to apply crack filler or sealcoating to stop water and debris from getting into the cracks and making them worse. Next, if at all possible you should restrict traffic in the affected area because vehicles driving over the weakened pavement will damage the asphalt surface further.
- Permanent repair of an area of alligator cracking in asphalt pavement requires digging below the surface to discover the underlying problems, then strengthening the asphalt’s base. This requires trained experts who will remove the damaged section of asphalt and replace it with a properly installed sub-base and fresh asphalt surface.
5. Longitudinal Cracking
Figure 5. Longitudinal cracks in asphalt occur because of pavement fatigue or due to asphalt shrinkage during low temperatures.
Longitudinal cracks in asphalt paving are cracks that run in the direction of asphalt application (along a driveway or road.) They can be caused by various factors including:
- poorly constructed joints
- shrinking/expansion of the asphalt with temperature cycles, and
- cracks reflecting up from an underlying layer
The presence of longitudinal cracks in asphalt paving is not load-related.
How to fix longitudinal cracks in asphalt
- Smaller Cracks (less than ½” wide) – Use a crack sealant to stop moisture getting into the sub-grade layers through the cracks, and to prevent raveling of the crack edges. Follow crack sealing with a fresh application of sealcoating over a larger area.
- Larger Cracks (more than ½” wide) – Engage an asphalt professional to diagnose the cause of your severe longitudinal cracks and recommend a long term solution.
6. Block Cracking
Figure 6. Block cracking can occur as a result of poor paving technique or the use of older, dried out asphalt.
Block cracking is a patch of large (about one foot or more), rectangular cracks in an asphalt pavement’s surface. This type of cracking typically covers large areas and may occur even where there is no traffic as this type of asphalt defect is not load-dependent.
Block cracking typically happens when the asphalt binder can’t expand and contract with temperature cycles because of age-related hardening, or because of poor choice of asphalt binder in the mix.
How to fix block cracking in asphalt
The strategy for fixing block cracking depends on the size and severity of the cracks:
Smaller block cracks (less than ½” wide) with little raveling – Use crack sealant to stop moisture getting into the sub-grade through the cracks and to prevent raveling of the edges. Follow crack sealing with a fresh application of sealcoating over a larger area.
Larger block cracks (more than ½” wide) and with raveled edges – Engage an asphalt professional to remove and replace the cracked pavement layer with an overlay.
7. Edge Cracks
Figure 7. Edge cracks are mostly caused by heavy traffic that is near the edge of the pavement. Inadequate drainage, poor underlying layers, and asphalt shrinkage can also contribute to the formation of edge cracks.
Edge cracks are longitudinal cracks that develop within one or two feet of the outer edge of a pavement and are more commonly seen on rural roads and driveways than in city streets.
Edge cracking happens because of a lack of support at the pavement edge and, because rural roads and driveways tend to be narrow, traffic is forced to drive close to these outer edges.
Poor drainage, poor quality base/sub-base, and asphalt shrinkage can also contribute to the formation of edge cracks. If you don’t take care of edge cracks, they will expand and lengthen, and more will appear toward the centerline of the pavement.
How to fix edge cracks in asphalt
You are much better off preventing edge cracks than fixing them. Here are a few tips on how to do this:
- Make sure there is good drainage at the pavement edge
- Confirm that you have a strong, cohesive base set
- Apply a layer of sealcoating as soon as the asphalt is cured to protect it from damage caused by weather, temperature changes, and overall usage.
If edge cracks appear despite your best efforts to prevent them, you can fix the problem as follows:
- Minor edge cracks – Use crack sealant to fill smaller cracks at the first sign of damage.
- More significant edge cracks – Fix damage using a patching or replacing method that addresses the root cause of the edge cracks.
8. Asphalt Upheaval
Figure 8. Asphalt upheaval is caused by an expansion of soil underneath the affected area. This expansion is often due to increased moisture in the soil or expansion of water as it freezes.
Upheaval is a localized upward movement in your asphalt pavement due to swelling of the sub-grade due to freezing or excess moisture. Frost heave is one example of this type of distress.
How to fix asphalt upheaval
Since asphalt upheaval is caused by problems in the pavement sub-grade, the best solution is removal of the affected area and application of a full-depth asphalt patch.
At Murphree Paving, we provide high-quality asphalt paving, asphalt repair and asphalt maintenance to residential, commercial municipal and industrial clients.
Call (662) 844-2331 during business hours to get a guaranteed same day response.
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