If you have an old concrete driveway, parking lot, or roadway that’s starting to crack and wear out, you might be wondering: Can you put asphalt over concrete? The short answer is yes; you can but it’s not always the best choice in every situation.
In this guide, we’ll explain how asphalt overlays work, when it’s a good idea, what challenges to expect, and how to make your new asphalt surface last for years.
Understanding the Basics: Asphalt vs. Concrete
It is only after we know the difference between the two materials that we will proceed with the answer to how asphalt can go over concrete.
What Is Concrete?
Concrete is a hard substance that is composed of cement, sand, gravel and water. It is very powerful and hard and that is why it is commonly applied in foundations, sidewalks and driveways. Nevertheless, concrete may crack and move with time particularly in the regions where there are freeze thaw conditions or on roads with high traffic.
What Is Asphalt?
On the other hand, asphalt is a pavement material which is flexible and composed of crushed stone and bitumen (a product of petroleum). It is mostly applied to roads, highways, and parking lots throughout the States as it is smooth, cost effective, and simple to fix.
The Short Answer: Yes, You Can Pave Asphalt Over Concrete
Most property owners would rather install asphalt over the concrete already there than to strip the concrete off entirely. This process is referred to as asphalt overlay or asphalt resurfacing.
This can save you when it is done right:
- Time
- Money
- Disruption to your property.
Nevertheless, one should know how the process functions and what circumstances should be ready to achieve a long-term effect.
How Asphalt Overlays on Concrete Work
Laying concrete over asphalt is not a simple task of simply laying new asphalt over it. It involves meticulous planning and assessment of the current concrete surface.
The way professionals usually do it is as follows:
Inspect the Concrete Surface
The initial one is to examine the current concrete in case of cracks, joints and damaged places. Concrete slabs contain expansion joints that can move, and they can make cracks in the new asphalt layer in case they are not controlled.
Repair or Fill the Joints and Cracks
Contractors will also fill the joints and cracks in the concrete with a strong and flexible filler, before laying the asphalt. This aids in the formation of a smoother surface and it also minimizes the chances of reflective cracking (when cracks located beneath the surface reflect through the asphalt on top).
Apply a Tack Coat
A tack coat (thin coating of emulsive asphalt) is used to ensure that the new asphalt bonding is firmly fixed to the concrete base. The step is essential in the effort to make the two materials collaborate.
Add a Leveling Course (if needed)
In case the surface of the concrete is not even a leveling course, a thin layer of asphalt is applied to even things out, and then a final layer is laid.
Lay the New Asphalt Layer
The last step is the new overlay (asphalt) with a roller (usually 1.5 to 3 inches thick). What is produced is a smooth surface that appears and feels new.
Advantages of Putting Asphalt Over Concrete
Using asphalt instead of concrete has a number of advantages particularly when the underlying concrete is structurally sound.
Cost-Effective
The process of concrete removal may be costly and tedious. You save on the demolition and disposal expenses by coating the top with asphalt.
Faster Installation
Asphalt can be installed usually within a day or two which means that you may use your driveway or parking lot much sooner.
Smooth and Quiet Surface
Asphalt causes a smoother and quieter ride and that is why most of the American highways are paved with asphalt.
Easier Maintenance and Repairs
Asphalt can be easily patched with small cracks or potholes as compared to concrete which in most cases needs bigger and more expensive repairs.
Enhanced Curb Appeal
New black asphalt immediately enhances a good look of your property making it look clean and well maintained.
Potential Drawbacks and Challenges
Although one can place the asphalt on top of the concrete, it is not always ideal. These are some of the things to be wary of.
Reflective Cracking
The concrete is not flexible and thus it is prone to cracking at the joints such that the cracks may later be transferred to the asphalt layer that has been laid over it. This is not always about performance, but it can be about appearance.
Drainage Problems
Concrete driveways usually include slope of drainage. When the asphalt is laid irregularly or excessively, then the water may not drain and cause puddles or early deterioration.
Stability Issues
When the concrete is wiggly, fractured, or unsteady, the asphalt applied over it will not resolve the issue, it will merely mask the issue in the short run. The weak spots can crack or sink over time on the asphalt.
Height Adjustments
The addition of the asphalt layer raises the heights of your surface and this may cause problems at the entrance of the garages, curbs, or sidewalks.
When Asphalt Over Concrete Is a Good Idea
An overlay of asphalt performs optimally when:
- The concrete base is well structurally sound.
- Minor cracks, no significant movement.
- You need a low-cost method of updating the surface.
- Proper drainage and slope can be adhered to.
It’s commonly done for:
- Driveways
- Parking lots
- Private roads
- Industrial yards.
When It’s Better to Remove the Concrete First
There are occasions when the concrete is too broken to allow the addition of a new layer of asphalt. Where the better long-term investment is to be made is in such cases one of full removal.
You ought to take away the concrete in case:
- It has big cracks, potholes or sinking slabs.
- The surface is not smooth or stable.
- Drainage problems or frost heave problems.
- The traffic is high in trucks in the area.
A clean base will enable the contractors to construct a stable asphalt base which will be much more durable.
How to Make Asphalt Over Concrete Last Longer
To get the most life out of your asphalt overlay, follow these maintenance tips:
Sealcoat frequently – Sealcoat should be applied every 2-3 years to prevent UV rays, oil and water damage.
Repair cracks promptly – Cracks do not take long to expand; by sealing them, water is not allowed to creep into the crack.
Eliminate excessive weight – Attempt to avoid putting very heavy weights on the surface.
Keep it clean – Clean up oil spills and sweep off debris.
Proper drainage – Standing water is the foe of asphalt life.
A good maintenance ensures that an asphalt overlay on concrete lasts 10-20 years or beyond.
Cost of Asphalt Over Concrete
It may range in price depending on the location, size, and condition on average:
Asphalt overlay: $3-$7 per square foot.
Removal and installing new asphalt: $8-$15 a square foot
This would imply that thousands of dollars can be saved by putting asphalt over concrete particularly in case of a large driveway or a parking lot.