Can You Put Asphalt Over Concrete?
We often hear the question, “Can you put blacktop over concrete?” There is a big difference between “can” and “should” when it comes to pouring asphalt over concrete. If elevation and climate allow it, newly poured concrete is a good base material to use before pouring asphalt down for your driveway. This technique is often done by multiple states and municipalities, though there are several considerations to make before choosing this option for your driveway.
If you’re considering laying asphalt over a concrete driveway, think about hiring a professional paver to handle the project. Putting blacktop over concrete can lean either way depending on the circumstances, so it’s best to get a professional opinion.
Can Asphalt Be Laid Over a Concrete Driveway?
The answer to this question is a bit ambiguous because it may be yes or no. Whether you should lay asphalt over concrete will vary depending on the situation. Asphalt can work well over concrete in some instances, while in others, it’s simply a recipe for disaster. Ultimately, it’s important to understand the situations in which asphalt can effectively be laid over a concrete surface and when it’s better to consider other options.
Before choosing to pave blacktop over your concrete surface, be sure you’ve considered all the downsides and side effects associated with this technique.
Things to Consider Before You Put Blacktop Over Concrete
While paving blacktop over concrete is a common technique used to create several types of roads, is it the right technique for your driveway? There are several long-term maintenance requirements you’ll likely need to be prepared to cover if you go this route. The biggest consideration you’ll need to make is how the stability of the concrete will affect the condition of the asphalt. This will vary depending on the climate, current condition of the concrete and other factors.
States in the northern part of the country are more likely to use asphalt due to its ability to withstand the constantly changing climate conditions. Concrete use can result in cracks and shifts, but this is not because of paving mistakes — it’s from temperature change.
If you are looking to pour asphalt over concrete, it’s important to know professionals must create a uniform base, clean and mill the concrete to ensure the asphalt overlay will have a good bond with the concrete. After milling, professionals will use proper adhesives and hot mix asphalt to correctly bond the asphalt over concrete.
Side Effects of Putting Blacktop Over Concrete
One of the biggest risks of laying asphalt over concrete is the potential for an unstable concrete base. If you’re using an already existing concrete base, it’s best to examine the quality and state of the concrete before adding blacktop.
An unstable concrete base can become compromised from the gradual cracking of concrete as it moves and shifts from the environment around it, with factors including:
- Temperature fluctuation
- Freezing and thawing of ice and snow
When pouring asphalt over concrete, the asphalt’s lifespan is determined by the quality and integrity of your sub-base, which in this case would be the concrete.
If there are cracks in the concrete or you have an uneven base, your asphalt driveway or parking lot can be compromised and crack where your concrete is cracked. One of the biggest concerns of putting asphalt over concrete is that the condition of the asphalt often depends on the condition of the concrete underneath it. If you don’t have a good foundation to build on, you will be running into trouble down the road with your driveway or parking lot.
To prevent the concrete from cracking and shifting, expansion joints are measured out no farther apart than two to three times the total thickness of each concrete slab. For example, if the concrete slab is 4 inches thick, the expansion joint should be between 8-12 feet apart. These expansion joints are most commonly made from rubber, metal or braided materials like stainless steel. After the concrete is poured with proper expansion joints, the asphalt can be poured on top of the concrete if you want that solution.
Is It Better to Remove Concrete First?
Older concrete that is cracked from the expansion and contraction of freezing and thawing ice should be removed and replaced before you pour asphalt. It is best to start from the ground up to ensure you have a structurally sound base. The quality and integrity of your driveway or parking lot can suffer if your concrete is not removed or replaced first.
Another reason to remove your concrete is to find out what is under the base of your current driveway. It could be sunken or shifted, revealing holes where water and ice can form, ruining your base of concrete. Sometimes it’s best to have the existing surfaces excavated so you can start fresh with a reliable sub-base.
Using asphalt for new driveways is often a better choice than using solely concrete for a few reasons. Asphalt has the ability to be flexible with temperature by contracting and expanding since it is not a compact surface like concrete is. It is much more affordable to install and maintain while having a fast installation time, so overall it is more economically efficient and cost-effective than solely using concrete.
Using primarily asphalt allows the surface to last longer and maintain its appearance for longer. Asphalt driveways with a proper, stable base may require less maintenance in the long run. Pouring asphalt over concrete can be cheaper in the short term, but you will have to spend money to fix and maintain it, costing more money over time. Digging up the concrete and laying asphalt may be expensive at first but can save you money in the long run due to asphalt’s longevity and little maintenance needs.
Discuss Putting Asphalt Over Concrete With CMI Paving
For the most educated and well-informed decision, consider having a pavement professional inspect your concrete surface.
We want our customers to have the correct information so they can make the right decisions when hiring professionals to pave their driveways or parking lots. Consider discussing your options with us to decide whether to pave blacktop over your concrete driveway or replace it. Don’t look anywhere else for professionals to newly install, repair or replace a driveway in Central Pennsylvania and beyond.
From residential and commercial paving to excavation work, we have the professionalism and expertise to answer your questions and deliver results that will satisfy your needs. Contact CMI Paving to discuss the possibility of laying asphalt on top of concrete.