What Causes Potholes to Form?

May 12, 2020

For road crews, the spring and summer are often spent filling potholes and other types of road deterioration that occur over the winter and early spring. There are a variety of causes of potholes in Nashville, TN, from temperature shifts to other environmental conditions. Here’s a quick overview of what you need to know.

Freezing and thawing cycles

Most people know that freezing and thawing cycles are perhaps the biggest issue for roads and pavement. Any area that sees freezing and thawing throughout the winter and spring will likely have to deal with this issue.

When small cracks and holes form in pavement, or when pavement does not have sufficient drainage or slope, water can puddle on top or seep underneath the surface. When it gets cold enough, the water that seeps below can freeze, expanding as it does so and pushing against the surface of the pavement, causing it to crack and weaken. As vehicles then drive over the top of this weakened pavement, potholes begin to form.

The problems with potholes are likely to be worse in areas where the roads have not been properly maintained, and where cracks do not get patched up before the winter months. Melting snow and ice will seep through those cracks, where it will become even more problematic.

Road salt

You may not know that road salt also plays a part in the formation of potholes, especially if the roads are already deteriorated due to frequent freezing and thawing cycles.

Salt can exacerbate the problems described above when water seeps under the surface and freezes to expand and create weak patches. The salt keeps the water in liquid form at a lower temperature, meaning it will not freeze until around 15 degrees. Any water that’s been mixed with road salt will go through the freezing and thawing cycles at lower temperatures than water without salt. Lower temperatures for these cycles increases the total number of freezing and thawing cycles that salt-bearing water will go through, which means a greater likelihood of potholes developing.

Rock salt used for roads is much coarser than standard table salt. It has the same molecular makeup, but it hasn’t been purified. It also has some additives to make delivery easier and to prevent it from sticking together when applied. Unfortunately, there’s little that can be done to prevent the additional damage to roads caused by road salt—it becomes a choice of whether you’d rather have dangerous, slippery roads, or roads that have more freezing and thawing cycles due to the use of the salt.

Ultimately, the repairs that need to be done to roads each year due to the freezing and thawing cycles and formation of potholes is almost unavoidable if you live in an area where freezing occurs. The more freezing and thawing you experience, the greater the problem will be.

For more information about the steps you can take to repair potholes after they’ve formed over the winter months and to learn more about the causes of potholes in Nashville, TN, contact RoadBuilders today.

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