In the paving game, there are times when property owners have to ask if it’s possible to put asphalt over concrete. The answer can be both “yes” and “no”, depending on several factors. While it is safe to pave over a concrete lot, the conditions of the asphalt and the concrete both must meet specific requirements. These can include, but are not limited to, the age of the concrete to be used as a base, the physical condition of the concrete, and the quality of the asphalt itself.   In this article, we look at the physical attributes of asphalt and the results of laying asphalt over concrete. 

Why Do People Put Asphalt Over Concrete?

Asphalt paving is one of the most important investments a company makes in its property maintenance budget. The components provide a long-lasting surface capable of withstanding years of foot and vehicle traffic.  Known as “repaving”, laying asphalt on top of a concrete base as an overlay, can result in better compaction of the asphalt material. It is an alternative to spending time and money on clearing and removing concrete surfaces, such as in commercial lots and on roadways.  Here are some benefits of laying asphalt on top of concrete:

• More Robust and Lasts Longer Compared to Concrete

Both concrete and asphalt are comprised of recyclable materials, but asphalt is more durable, thereby creating a double layer of protection when laid on concrete. In terms of longevity, asphalt can last up to twice as long as a concrete surface. This is mainly due to its flexibility in contracting and expanding in certain temperatures. 

• Repair, Installation & Maintenance Are Cheaper and Easier 

Asphalt paving contractors will quote a lower price point for the installation, repairs, and maintenance with an asphalt surface. As concrete is more susceptible to fluctuating temperatures and heavy traffic flows, having an asphalt overlay can protect the surface from damage. 

• Maintains Its Aesthetic for a Longer Time

Using asphalt as protection of the concrete provides a unified and aesthetically pleasing look to the commercial lot. Leaving a plain slab of concrete, or any one of the various colours available in some areas, can draw attention to stains, cracks, and damage. 

Why You Should Not Put Asphalt Over Concrete

Just as there are reasons to use asphalt on top of concrete, there are just as many reasons not to. Things to consider include the condition of the concrete base, the potential for damage to both, and the costs associated with an asphalt overlay. 

• Concrete May Not Be Stable

Using concrete as a base for asphalt paving requires the concrete itself to be stable. Unlike asphalt, concrete can be poured over any type of surface and becomes an uncompacted surface once it hardens. With use, the components of the concrete can become unsettled, and they can shift, causing instability throughout the surfaced areas. 

• Expansion Joints Can Result in Cracking

Concrete can develop expansion joints or cracks. These form as sections between the slabs when poured. Traffic, weather, and fluctuating temperatures can see these joints move and pivot, leading the concrete to crack. Having an asphalt overlay will cause the movement to adversely affect the condition of the top. Asphalt can then be damaged, and cracks will appear in the areas where the concrete cracks form. 

• It Can Decrease Longevity

While in most cases, two layers are better than one, when it comes to laying asphalt over concrete, this is not always the case. With the uncertainty of the stability of the concrete and the base, the longevity of the asphalt coating can be reduced, in some cases quite significantly. Depending on the condition, asphalt repairs may be required more frequently. This can leave the surface needing replacement long before an expected time of 30 years.  

• Temperature Fluctuation Can Affect Durability

The fluctuating temperatures we see in Canada can affect the overall durability of concrete. Concrete alone is known to heave, buckle, and crack in subzero temperatures. Using a deicer and salt can also damage the concrete surface. These effects can be long-lasting, especially within the concrete components. Laying asphalt over concrete only hides these deficiencies and doesn’t actually repair them. 

• The Subbase Should Be Compact

Asphalt requires the concrete to be in excellent condition to act as a base. The subbase of the concrete can also affect not only the concrete surface but the asphalt as well. In many cases, knowing the condition of the ground below the concrete can only be confirmed by digging up the substance. Concrete doesn’t need a stabilizing base, thus allowing it to be used on sunken or surfaces with inadequate support. Only a compacted subbase will ensure the durability and longevity of placing asphalt over concrete. 

• Cost of Putting Asphalt Over Concrete

To avoid the hefty demolition costs of removing a concrete base, the cheaper option to lay asphalt over the concrete is commonly chosen. This can actually cost a business more money down the road due to frequent repairs for the reasons mentioned in this article. With these unforeseen circumstances, the entire project may need to be redone. 

Get a Professional Opinion from Sure-Seal Pavement Maintenance Inc.

So, to answer the question “Can you put asphalt over existing concrete”, it is better to leave it up to the professionals at Sure-Seal Pavement Maintenance Inc. to determine. We have the knowledge, experience, and advanced equipment to help you make an informed decision about whether your concrete lot can withstand asphalt paving.  As the leading commercial installation, repair, and maintenance asphalt contractor in the GTA, we strive to provide 100% customer satisfaction. Call us today to learn more!