Using Asphalt To Patch Concrete

Over time, any asphalt paving will wear down. A combination of the water cycle (cooling and heating and expanding and contracting) and the pressure from vehicle tires will cause damage to any driveway, parking lot, or road. Weather and use will necessitate one thing: repairs. Asphalt, fortunately, can be repaired in various types of ways. From sealing cracks and plugging surface holes to full-bore repair, asphalt is easy to work with. Concrete on the other hand, is a bit tougher. Often, concrete can only be repaired by replacing entire slabs of it, meaning huge chunks of concrete must be removed and then new ones laid. This process is costly, time-consuming, and a main reason concrete is not the preferred road material. 

How it works

Fortunately, asphalt and concrete are very similar substances. That’s why they have so much overlap in their applications. Both concrete and asphalt are made primarily from aggregate. Aggregate are small rocks, pebbles and stones. They form the main body of asphalt and concrete. If you’ve looked at most concrete, and compared it to the asphalt in the road, you’ve probably noticed how much larger the aggregate in asphalt is. Concrete is composed of smaller particles in general, the size of grains of sand. Sometimes the size of the particles ranges up to a few millimeters, but usually it is under 1. Asphalt however is typically composed of a much coarser aggregate. Pieces of asphalt particulate range from under one millimeter up to under 10. In general, asphalt’s aggregate averages out to a larger size, of 1 or more millimeter in diameter each.

The other main ingredient in both asphalt and concrete is binder. Binder is a type of glue that holds everything together. In asphalt, binder is petroleum-based. It is made from refined oil, and it composes about 5% of the total body of the asphalt. In concrete, the binder is 10-15% cement, 15-20% water, and 65-75% aggregates. The cement is the substance that creates the glue –  functioning as a binder – in concrete. It is made from various different ingredients, such as lime, silica, sulfur trioxide, alkaline, iron oxide, alumina, and calcium sulfate. When water is applied, these ingredients form a tough and resilient binder that holds together concrete’s aggregate.

Due to the higher content of binder, and the smaller aggregate size, concrete has different uses from asphalt. Asphalt is often used for roads and other asphalt paving, like driveways, parking lots, and trails. Concrete can be structural, composing columns, walls, and more. 

Can asphalt be used to patch and repair concrete?

Simply put, the answer is yes. Now using asphalt patches to repair concrete isn’t a one-size-fits-all solution, but it is very common, and easy to do. Concrete actually makes a fantastic base material for asphalt. It allows strong compaction, and, every year, miles and miles of concrete roadway are paved over with asphalt. 

Laying asphalt on concrete provides several benefits:

  • Asphalt is highly weather resistant, especially when seal coated. Asphalt seal coating is the number one choice for durable and efficient protection.
  • Asphalt is much cheaper to lay than concrete. Rather than replacing huge slabs of concrete for repairs, you can work on the new layer of asphalt for much cheaper. Asphalt is also 100% recyclable, making it an environmentally friendly choice.
  • Because asphalt is 100% recyclable, it is easier to come by than concrete. Paving contractors can tear up existing asphalt, re-pulverize it, and lay it as new asphalt. Not only that, but they can do it all on location with the right gear.
  • Asphalt is more durable. It can handle weather and temperature fluctuations much better than concrete.

Patching concrete with asphalt

When it comes to patching holes and cracks in concrete, asphalt patch kits work great. Just follow a few steps:

  • Clean up the hole to be patched. Clean up any loose gravel or rocks, or other debris that may have made their way there. You can use a brush or broom to do so. 
  • Apply the asphalt patching material. Be sure to read instructions on the patch kit first. You may need a polymer sealant applied in the hole between the two.
  • Once the patch is applied let it set. You may need to blow hot or cold air on the patch depending on the kit you are using.

Why NOT to patch concrete with asphalt

Although it makes a good surfacing substance, there are some reasons not to use asphalt in tandem with concrete.

  • The concrete under your asphalt can crack. This can make the asphalt weaker, and be a real headache to fix. Now you have to repair two layers of different material. If you aren’t sure about the concrete you will be laying your asphalt on, then don’t do it!
  • Expansion joints. Because concrete handles temperature fluctuations differently, it has something called expansion joints. These will move over time and can cause the asphalt above to develop cracks along those lines.
  • When there is already a foundation for asphalt, the base underneath is unknown. How strong is the earth below the concrete? How many years will it last before totally new paving is required? Changes in the ground below concrete can cause the asphalt to shift, heave, and crack. This lowers the lifespan and necessitates more frequent repairs.

Figuring out how to repair your concrete?

Whether your paving conundrum is concrete, asphalt, or anything else, Reliable Paving, can fix it. We have been in the paving industry for 35 years, and offer a wide range of services.

  • Asphalt seal coating
  • Asphalt paving
  • Concrete paving
  • Concrete seal coating
  • Repairs, such as crack filling and patching
  • Re-striping
  • And much more!

Send us a message today to see how we can lay new pavement, repair damaged pavement, or see what our full range of services is.