Hot Mix Asphalt 101

Everything You Need To Know About This Common Aggregate Product Asphalt pavement is widely used in road construction and other urban infrastructure projects and can be found almost everywhere in and around urban centers. You may know asphalt pavement is a mixture of aggregates, binders, and fillers. But you might not know that there is […]

hot mix asphalt what is it anyway

Everything You Need To Know About This Common Aggregate Product

Asphalt pavement is widely used in road construction and other urban infrastructure projects and can be found almost everywhere in and around urban centers. You may know asphalt pavement is a mixture of aggregates, binders, and fillers. But you might not know that there is more than one kind of asphalt! We’re going to talk about one of the more common aggregate products, hot mix asphalt, and go over some of its uses.

What Is Hot Mix Asphalt?

Hot mix asphalt is a variety of asphalt that contains around 95 percent aggregates (like crushed rock, sand, gravel or slags). These products are stuck together using asphalt cement, a crude oil product. And, as the name hints, hot mix asphalt is produced at high temperatures, usually between 150 and 190 degrees Celsius.

Since it must maintain its temperature when poured, the weather cannot be too cold—the outdoor air temperature must be above 4 degrees Celsius (40 degrees Fahrenheit).

Common uses for HMA include the paving of highways, roads, driveways, and parking lots. HMA is flexible, weather-resistant, and can easily repel water.

How Is Hot Mix Asphalt Placed?

Hot mix asphalt is usually used to pave roads. When it’s used for paving, hot mix asphalt is brought to the paving site and then dumped into the hoppers of a paving machine. The asphalt is then applied (typically in 4- to 8-inch-thick layers) and compacted using a heavy heated roller. The road can usually be driven on as soon as the pavement cools!

The layering system for paving has the lower layers acting as support for the top layers. For a smoother surface, the lower layers are typically made up of aggregates that help prevent rutting and failure. The aggregates in the top layer are chosen for their friction and durability.

How Is It Categorized?

Hot Mix Asphalt is usually categorized into the following types:

  • Dense-graded mixes—depending on the size of the aggregates used, these can be further categorized into fine-graded and coarse-graded. Fine-graded mixes have more sand and smaller stones compared to the coarse-graded mixes.
  • Stone matrix asphalt—is manufactured with a high percentage of asphalt cement and has asphalt binders and fibres. Due to its expensive cost, stone matrix asphalt is normally only used for large projects.
  • Open-graded mixes—come in two types: friction course and asphalt treated permeable bases. Friction course mixes are used for the top layer of pavement and must have at least 15 percent air voids. Asphalt treated permeable bases are used as a base layer for dense-graded asphalt and Portland cement mixes to drain water away from the top layer of pavement.

Read More: How Hot Mix Asphalt Can Be Eco-friendly

What Are The Advantages Of Hot Mix Asphalt Over Concrete?

Asphalt and hot mix asphalt are preferred over concrete for a few different reasons. For starters, asphalt is more durable and has lower construction and maintenance costs than concrete. Asphalt is also smoother than concrete. This is important because smooth roads last longer, are generally quieter, and improve fuel economy and vehicle longevity.

How Is Hot Mix Asphalt Different Than Warm Mix Asphalt?

Because it’s manufactured at a different temperature. Warm mix asphalt (WMA) is manufactured at temperatures ranging from 200 to 250 degrees Fahrenheit. It often contains binding materials and additives, such as wax, emulsions, and zeolites, for an easier pour and spreading at lower temperatures. The lower temperature requires fewer resources and fossil fuels for manufacturing and also emits fewer fumes when being poured and spread.

WMA is used to pave cart paths, driveways, walking paths, roads, and highways. Due to its lower temperature and slower heat loss, WMA can be used during cooler weather.

Depending on its uses for the construction project, asphalt pavement will either be manufactured at very high temperatures—hot mix asphalt—or at lower temperatures—warm mix asphalt. Both types of asphalts have various qualities and each is preferred for different types of projects. If you need more information on which type of asphalt is best for your construction project, contact your local hot mix asphalt supplier.

Read More: Using Cigarette Butts In Hot Mix Asphalt

Hot Mix Asphalt Patching Tips

Sometimes, for whatever reason, damage can happen – most of the time you can blame it on the weather, salt and snow. But, there’s a solution to every problem. Asphalt patching is a cost-effective solution to repair potholes and cracks. Patching protects asphalt surfaces and foundations from continued damage. If left alone, this damage will worsen over time and become more costly to repair.

Asphalt patching improves the safety and appearance of roads, driveways, and parking lots. It is a quick solution that yields lasting results. And best of all, it’s not too difficult of a job.  By patching asphalt before the damage worsens, you can add years to the life of your pavement. And you will improve its appearance, safety, and function.

You can use either cold or hot asphalt mix for patching, but hot mix asphalt provides a longer-lasting result. To repair pavement on your property, consider the help of hot mix asphalt suppliers. And read on to learn more about patching techniques.

There are two common types of asphalt patching—surface patching and remove-and-replace patching. Surface patching is popular for residential projects. It is faster and easier than the latter type. When completing a surface patch, you will need to add asphalt glue to the patch area. You will then apply (or have a professional apply) hot mix asphalt on top of the existing asphalt surface.

Remove-and-replace patching takes more time. Although it involves more work, it can result in a longer-lasting patch. If you want to try the remove-and-replace patching method, follow these steps:

Remove Damage & Square The Hole

Remove damaged pavement with an asphalt saw, or with a hammer and a chisel or screwdriver. Square the asphalt, making the edges straight along the sides as well as up and down. This will make it easier to repair and ensure a longer-lasting patch. An asphalt saw is best to use for squaring potholes.

Clean The Pothole

To prevent future damage to the patch, remove any plant life in the pothole. You can pour vinegar on the plants to kill the roots if you are unable to uproot them. Plants left to grow will crack the patch and grow through it over time.

Remove any other debris and chunks of asphalt. Use a stiff broom to sweep out any leftover pieces. And clean as far down as needed to get a solid clean base.

Restore The Foundation

Fill the hole with a coarse gravel and sand mix until it is only one inch deep. Tamp the aggregates and compress as you fill in the hole. A solid base will provide a long-lasting patch.

Measure the size of the damage—this will determine how much asphalt you will need to patch the holes and/or cracks. Square the edges of the pothole so it will be easier to measure the size of the hole—and multiply the length by the width. For example, a 1-foot by 1-foot hole will be 2 square feet.

Your asphalt supplier can help determine how much asphalt you’ll need.

Patch The Hole

Although cold asphalt mix is easier to use, hot mix asphalt will provide a more durable patch. Hot mix asphalt suppliers will deliver heated asphalt for projects of all sizes. They can even do the final step of the patching for you professionally and efficiently.

To fill and patch the hole, add a half- to a full inch of asphalt. Tamp down and repeat until the asphalt is overfilling the hole. If you don’t have a vibrating plate or tamping machine, you can use a metal tamper or a lawn roller.

And if you don’t have these tools either, then you can use a piece of plywood. You may want to oil one side first so it doesn’t stick to the asphalt. Lay the plywood on top of the patch and drive over it with a vehicle.

If you notice the pothole is not completely full after this tamping, add more asphalt. Tamp and repeat until it is level with the surrounding pavement. The quicker you finish patching, the better. You will need to complete the patching before the asphalt sets, dries, and hardens.

Seal The Patch

To prevent the elements and de-icing salt from damaging your patch, make sure to seal it. Wait four hours before sealing the patch so it has time to cure.

Only seal patches in dry warm weather. If you have to patch a pothole in the winter, wait until warmer spring weather to seal it. Use a paintbrush or roller to apply a thin seal coat to the patch. Wait for it to dry before applying the second coat.

If using hot mix asphalt, wait at least 24 hours before driving on the patch so it will have time to harden.

The Takeaway

Although we see it around us every day, asphalt isn’t something we often think about. While we may not realize its importance, we rely on asphalt for getting us to where we need to go every single time we drive! That’s why it’s important to understand how it works and the difference a quality product can make. If you have any questions and are still not sure what to use in your next project, just give us a call – we got you.


Jon Blair
Jon Blair is an integral part of the A.L. Blair Construction team, a company that has been setting high standards in the aggregate industry since 1932. With a heritage deeply rooted in Eastern Ontario, Jon is committed to delivering quality and reliability in every project.

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