Asphalt is a popular surface for driveways and parking lots due to its durability and low cost. However, asphalt can crack over time if it’s not maintained correctly. This blog post will look at the top seven reasons why asphalt cracks and how you can prevent it from happening!
Any paved surface can develop cracks if you don’t keep up with maintenance. Cracks in a driveway or parking lot develop due to asphalt surfaces exposed to water, heavy vehicles, seasonal temperature changes, heavy traffic, and sun exposure. But with maintenance, asphalt can look good and maintain its beauty for decades!
1- Harsh Weather
Seasonal temperatures can cause the expansion and contraction of the pavement. The shrinkage of the asphalt when it contracts during the warmer months, combined with the expansion during the colder months, can be rough on asphalt.
With timely maintenance of your asphalt, extreme temperature cycles are not a problem. However, without a good seal coat every couple of years, asphalt shrinkage can occur with continuous exposure to the elements, bringing cracks with it!
2- Water Seepage
If your contractor did not plan for proper drainage when installing your asphalt, cracks could appear regardless of your maintenance routine. Poor drainage allows water to sit on the pavement surface.
As asphalt expands in the summer, water seeps into the asphalt. However, as winter approaches and the pavement contracts, cracks form where the water turns into ice. Further damage occurs as the cycle of water seepage continues, bringing a weakened base.
3- Poorly Designed for Traffic Flow
Traffic loading is a crucial concept for asphalt contractors. They must ensure that the types of asphalt they install can withstand the heavy pressure typically caused by heavy machinery or extreme traffic.
Load-related deterioration occurs when a contractor uses a low-strength asphalt mix for a high-traffic area.
4- Not Using Quality Materials
The pavement surface can crack due to many stressors without proper maintenance. However, asphalt cracks often begin with poor installation.
An improper paver operation generally uses a weak asphalt mix with a poor underlying layer, contributing to pavement failures. The asphalt should have the right amount of binder, aggregate, and air voids.
Binder Considerations
Too much asphalt binder makes the material soft and susceptible to rutting. With too little binder, the material will be too brittle and susceptible to cracking.
Binder is a “waterproof, thermoplastic adhesive. In other words, it acts as the glue that holds the road together. In its most common form, asphalt binder is simply the residue from petroleum refining.” (1)
Aggregate Considerations
The mix should also have the right amount of aggregate. If there is too much asphalt aggregate, it will be susceptible to raveling (the deterioration of pavement by losing asphalt and rocks). If there is too little aggregate, it will be susceptible to rutting and potholes.
“Aggregates (or mineral aggregates) are hard, inert materials such as sand, gravel, crushed stone, slag, or rock dust. Properly selected and graded aggregates are mixed with the cement- ing medium asphalt to form pavements. Aggregates are the principal load-supporting components.” (2)
An experienced asphalt contractor understands that poor-quality materials can cause cracking down the road. A poor mix with a lack of asphalt binder creates a poor bond between the asphalt materials.
5- Laying Over a Poor Surface
Another issue bringing cracks to your surface right from the initial paving is laying a new asphalt surface over the old pavement with previous cracks. Underlying layers contribute to the stability of pavement. Without a suitable subsoil and aggregate layer, cracks develop quickly.
The asphalt mix seeps into those cracks, and as the new asphalt surface cools and contracts, the previous cracks reappear.
6- Asphalt Pavement Thickness
The pavement thickness can also contribute to cracks. An experienced contractor will lay three inches of asphalt above the base layer.
A contractor with shoddy business practices can easily cause your pavement problems by laying too little asphalt.
7- Poorly Constructed Joints
Joints occur when your contractor lays a fresh batch of hot-mix asphalt (HMA) adjacent to an existing lane. (3)
A poorly constructed joint can fail prematurely from raveling or cracking and may allow water infiltration into the base and subgrade.
A knowledgeable contractor will “roll transverse joints parallel to the joint” to prevent lumps and bumps that can lead to cracking down the road. (4)
Another type of poor construction to watch out for is when segregation occurs. “Areas of coarse aggregate (rock pockets) [can] occur randomly across the length and width of the layer… as a longitudinal area along one side of the paver width, or… transversely across the lane at the end of a truck-load of mix.”
A reputable asphalt contractor will have the experience to avoid these problems so that you don’t have to deal with asphalt cracking down the road.
Asphalt Cracking Types
Longitudinal Cracking
Longitudinal cracks run parallel to the asphalt’s centerline or laydown direction. These cracks typically occur due to asphalt pavement failures such as a poorly constructed joint, overloading conditions, traffic congestion, hardening of the asphalt, and insufficient asphalt mix.
Transverse Cracking
Transverse cracks usually come from thermal expansion and contraction of the asphalt. This happens when there are extreme temperature changes within a short period of time. These cracks can also come about through traffic congestion, poor asphalt mix design, and heavy loads on the pavement.
Block Cracking
Block cracking (rectangular cracking) is a pattern of large (typically square) interconnected cracks. Block cracks form when asphalt pavement dries out in the sun or when a contractor lays down a thin layer of pavement.
Fatigue Cracking
Fatigue cracks, also called alligator cracking, form in the shape of an alligator’s skin. These cracks come with “load-related deterioration resulting from a weakened base course or subgrade, too little pavement thickness, overloading, or a combination of these factors.” (5)
Transverse Cracking
Cracks forming because of thermal expansion and contraction are called transverse cracks. This happens with extreme temperature changes within a short period of time. Longitudinal cracking is a type of transverse cracking that occurs parallel to the pavement’s centerline or laydown direction.
Slippage Cracking
Slippage cracks are crescent-shaped cracks that form when asphalt pavement lays over a surface that is not compacted correctly.
Edge Cracking
Edge cracks typically occur at the pavement’s edge due to poor compaction, raveling, and lack of support at the border.
Reflection Cracking
Cracks reflecting an existing joint “occur directly over the underlying cracks or joints. ‘Joint reflection cracking’ refers to cracks arising from underlying PCC pavement joint movement. Reflection cracking can also occur over existing HMA pavement cracks, cement or lime stabilized base, etc.” (6)
How To Prevent Asphalt Surface Cracking
A good maintenance routine is the best way to prevent asphalt cracking. This includes sealcoating your asphalt every two years and fixing any cracking as soon as it appears. The surface treatment of your pavement can prevent cracks before they start!
Sealcoating protects asphalt from the sun’s UV rays, which can cause asphalt to dry out and become brittle. Sealcoating also protects asphalt from the elements, such as water, oil, and gas.
It’s crucial to fix existing problems as soon as they appear. The best way to repair cracks is with a hot asphalt filler. This type of crack filler is heated to 400 degrees and applied. The heat from the asphalt crack filler helps to seal the cracks and keep water out.
Hot asphalt crack fillers are also less likely to cause patch failures in the winter when the ground is cold. Cold asphalt crack fillers can freeze and contract, causing them to break down and allow water into the cracks.
Finally, the best way to prevent asphalt cracking is to hire a reputable asphalt contractor. A good asphalt contractor will have the experience to avoid these problems so that you don’t have to deal with asphalt cracking down the road.
When it comes to asphalt, cracks are inevitable with time. But by following these tips, you can help extend the life of your asphalt and prevent costly repairs.
Our Experienced Asphalt Contractors Can Help
At AMP Paving, we work with you to ensure your asphalt is properly maintained and repaired. We are asphalt experts with decades of experience in asphalt paving, repair, sealcoating, and more. Our commercial asphalt services include roadways, parking lots, striping, ADA requirements, and signage.
We take pride in our work and go above and beyond to exceed your expectations. Contact us today to get started on your project!