What is Asphalt Raveling?
Asphalt is one of the most popular paving materials in North America, and for a good reason – it’s versatile, tough, and affordable. There’s nothing better than the look of a shiny new blacktop, but that blacktop won’t keep shiny and beautiful without regular maintenance.
Though it’s tough, asphalt faces many enemies from the elements and from the people that use it. Without proper maintenance, you could see issues like cracking, pitting, and raveling. Raveling is one of the most common residential asphalt issues but doesn’t have to be if you take the right steps. Let’s learn what asphalt raveling is and how to keep it from happening to your asphalt.
Figuring Out Raveling
Raveling is the slow disintegration of your asphalt from the top down resulting from aggregate loss. Essentially the top layer of aggregate breaks free from the asphalt binder, which causes raveling issues.
Raveling starts subtlely but slowly makes its way through your asphalt, leaving you with an ugly pockmarked and gray asphalt driveway that is much more susceptible to damage than well-maintained asphalt. Raveling tends to occur in older, unmaintained asphalt driveways that are already showing signs of oxidation.
Causes of Asphalt Raveling
Issues with raveling begin when your asphalt’s aggregate particles separate from the asphalt’s binder. There are several causes for asphalt raveling including:
- Weather Issues – Sun, rain, and ice will cause subtle damage to your asphalt over time by weakening the bonds between the asphalt binder and aggregate. Weather damage leads to oxidation, a chemical reaction that further weakens the bond between aggregate and binder.
- Poor Installation – Inadequate compaction during installation can lead to premature raveling, which usually occurs when the asphalt is installed during temperatures that are too low.
- Separation of Aggregated Particles – Also known as aggregate segregation. Low-quality aggregate lacks fine dust particles (aggregate fines). (Asphalt contains a variety of aggregate sizes from ¾” rock down to sand. When it is installed, the asphalt must maintain a consistent internal distribution of these aggregates. During installation, if the laborers that rake the asphalt lack experience, they can accidentally cluster the larger aggregates into small areas. Without finer aggregates evenly distributed in these clusters, the asphalt binds poorly, causing the aggregates to ravel out of the asphalt mat). Without fine dust to bind to, the binder bonds to coarser particles, which are more likely to wash away, causing raveling.
- Mechanical Dislodging – Separation can happen from vehicles, especially vehicles likely to aggravate the surface like snowplows, snow tires, or oversized tires.
How to Repair Raveling
The type of asphalt repair for raveling depends on the extent of the damage. There are two basic types of raveling repair:
- Localized repair – If raveling is only happening in small spots or is not that extensive, you can execute a localized repair. If it is early enough in the raveling process, you can halt the process by sealcoating as soon as possible. If repairs are necessary, skin patching or infrared heating is the best solution. Mild raveling is not a structural problem that warrants a major concern; your driveway is still functional. But you do want to prevent extensive raveling because it is ugly and expensive to repair.
- Extensive repair – If your entire asphalt driveway is raveling and it has been raveling for many years, this may require a mill and overlay or full-depth removal and replacement to correct the problem. Extensive and prolonged raveling can become structural problems that lead to failed asphalt.
How to Prevent Raveling
Ideally, you’ll keep raveling from happening in the first place with a regular sealcoat. Sealcoating involves a topcoat of asphalt binder and other compounds that defend your asphalt against rain, UV damage, and raveling.
Homeowners can sealcoat the asphalt themselves, but professional sealcoating for the most thorough job is recommended. Regular sealcoating will keep your asphalt looking shiny and black and will keep away damage like raveling and other issues. Asphalt pavement experts recommend re-sealing your asphalt every four to six years.
No More Raveling
Raveling breaks up the bonds between your asphalt’s binder and aggregate, creating a host of issues and awful-looking asphalt. All raveling can be repaired, but homeowners should regularly sealcoat their driveways to keep raveling issues from happening in the first place. If you’re ever unsure how to handle raveling or sealcoat, contact Colorado Pavement Solutions for a free estimate on the best way to repair your raveling issues.