We’re going to break down the pros and cons of building a new driveway out of asphalt millings instead of gravel, and why you shouldn’t add them to an existing gravel driveway.
If you have a project coming up that requires gravel, you might want to consider using asphalt millings instead of gravel. Asphalt millings is the name for the top layer of asphalt roadways that has been removed and pulverized to a small material as part of an asphalt roadway’s maintenance process. Sometimes, those asphalt millings are reused in the new layer of asphalt roadway, but not always. Asphalt paving contractors are starting to move into recycling more of the old millings, but for now asphalt millings are still a nice alternative to gravel. There are many advantages to using asphalt millings over gravel in your next project.
Pros
- It’s less expensive. Using a recycled product like asphalt millings is less expensive than buying new materials. In 2023, the cost savings in southern Illinois were in the $7 dollar a ton range. Gravel is sourced from quarries along the Ohio river, crushed, cleaned, and transported, which all costs money. Utilizing asphalt millings rather than gravel can lower the material cost of your project by upwards of 25%. If you value recycling old material, this is also a plus for the pro side of this argument, as you’re using and old road top to create your new driveway.
- It’s durable. asphalt millings stand up to heat and cold as well or even better than gravel. When we say stand up to the cold, we mean that the freeze/thaw cycle in the wintertime around here isn’t as hard on your driveway when it’s built out of millings. Overall your driveway will not develop as many potholes as quickly as a gravel drive will, once it’s had a good amount of time to pack in – ideally over a long hot summer. That being said, once you have a pothole develop in an asphalt milling driveway, it will need addressed as it will continue to chunk out and get bigger over time.
- It’s Lower Maintenance. Gravel tends to shift over time, or even disappear due sinking down into the dirt, especially during the freeze and thaw cycle. Asphalt millings will harden into a thick crust or sheet over time and stay put much better than gravel. That also means it is less likely to need to be repaired or replaced in the future, no gravel driveways with deep ruts, and less maintenance than alternatives. This assumes your driveway is built and correctly to start with which is where we come in.
Cons
- Smell. Most wouldn’t ever consider it, but the smell of somewhat fresh millings on a hot summer day can be a turn off. It smells just like you might think, road construction. Over time this will go away, but the first summer this is certainly something to think about.
- Aesthetic. Some people don’t like the way it looks. A gravel driveway has a nice uniform white/gray look to it, which will match most of the neighbors driveways. Millings has a different look to it, it’s very dark, as you would expect. But it’s not as smooth and uniform of a dark color like a paved highway. It has some different shades to it, and some of our customers are turned off by this.
- Compatibility. Once you decide to go this route, which we do believe is a good way to go, you need to stick with it in the future unless you are doing a major overhaul of your driveway. Over time, your drive will need maintenance and re-coated with a layer of millings to smooth it out and refresh it, just like a gravel driveway does. If you were to add gravel onto of the hard layer of millings underneath, the gravel will work it’s way to the sides/middle and off of your driveway over time. You can think of this like pouring gravel onto of concrete and then trying to drive on it, it just doesn’t make sense. Over time, your tires will move the lose material out of the way and you will be down to the hard surface underneath. The same thing goes for asphalt millings. If you were to top coat the drive in another round of asphalt millings, those asphalt millings will fill any potholes and uneven surfaces, harden up, and be just as good as it was when it was new – no loosing of material.
Why you shouldn’t add millings to an existing gravel driveway.
In most cases – but not all, we don’t recommend adding millings onto an existing gravel driveway. The main reason is that once you mix your loose 3/4″ or 1″ gravel with the asphalt millings, you lose the best benefit of having them in the first place, and that is the durability and compaction that you would otherwise end up with if you just had asphalt millings. Those marbly rocks will mix in and not let the millings bond together. Asphalt millings retain a good chunk of the oil that they are paved with in the first place, and when they are drove on and compacted together, they go back together just like asphalt, but maybe not quite a smooth. That said, you mix loose rock in with it, and they can’t bond together.
The exception to this is when you plan to do some serious work and add a good 4″+ thick layer over an existing driveway. Once you get beyond a thickness of a few inches of asphalt millings, then you start to reach point when the rock doesn’t have a chance to make it’s way to the top and interrupt the bonding.
A good example of when adding millings to a gravel drive did make sense was a recent job we did for a customer with steep section of driveway. The main problem was water washing their gravel to the bottom of the hill, which was partially a gravel issue and partially a drainage issue. We were able to fix both by adding a thick 6″ layer of asphalt millings, and shaping it up correctly. We added a nice crown to split the water off to both ditches, and in doing so out of millings, compacted it enough to where when it does rain hard the water doesn’t take anything with it – because there isn’t anything loose left to take.