Most Americans use the terms asphalt and blacktop interchangeably, referring to roads and driveways. However, blacktop comes from asphalt and it's a totally different mixture. If they're different mixtures, why do potholes appear in both roads and in driveways in the winter?
How Asphalt and Blacktop Are Made
Blacktop and asphalt are both made stone and bitumen. The stone ingredient in both is crushed and mixed with the bitumen, which is a dark material that binds the crushed stone together. Asphalt is used on major highways and other main roads that get more traffic than the roads in your subdivision or your driveway. This means that the mixture must be more durable than the mixture that you'd find on residential streets.
Blacktop has more crushed stone in the mix and must be heated to a higher degree than asphalt before being laid on the graded road or driveway. And because both asphalt and blacktop are black, heat is quickly absorbed into it, melting winter snow and ice, which makes your morning commute a bit safer. Even so, you still get potholes the size of Texas and they can be annoying to drive over.
So How Do Potholes Form?
Potholes, or chuckholes as they used to be called, develop through a process called the freeze-thaw cycle. Water gets into cracks in the asphalt or blacktop and freezes. Water expands as it becomes ice and over time creates larger and larger cracks as it freezes and thaws. Coupled with the weight of vehicles driving over the weakened roads, you get winter potholes that can throw your vehicle out of alignment or give you a flat tire after you hit them.
The road salt that is sprinkled over the roads to melt ice increases those freeze-thaw cycles and can contribute to the widening and deepening of the potholes. You might notice pockmarks on your driveway if it's iced over and you sprinkle salt to melt the ice and don't shovel it off quickly. Read all directions before adding salt to your blacktop so you can better keep your driveway intact. Your driveway is also subject to the freeze-thaw cycle that besets asphalt on the major roadways. It just doesn't get all the traffic and takes longer to create those annoying potholes.
Fixing the Problem
Winter potholes are not only annoying, but they are also a safety hazard. If you see a major pothole, now you can report it via your smartphone. For the potholes in your driveway, you'll have to DIY or call an asphalt paving pro.