What Is Asphalt Made Of? A Complete Guide

When planning a paving project, it’s helpful to know what types of materials are available and what those materials are composed of.

This allows you to make an informed decision on the best products to use for your project.

Asphalt is one of the most commonly used paving materials because of its flexibility, durability, and long lifespan.

In this blog, we’ll explain what exactly asphalt is made of and what occurs during the manufacturing process.

Key Takeaways

• Asphalt pavement is a combination of aggregates, which are solid mineral materials, and a binder, which is the sticky substance holding the minerals together.
• Asphalt is traditionally mixed, stored, transported, and poured at high temperatures.
• Mixes can vary in composition, and the best mix for a project depends on the climate of the area and what the surface will be used for.

Asphalt 101

Asphalt pavement is a popular material for roads, driveways, parking lots, and many other surfaces.

If you’re considering using asphalt for a paving project, you should know exactly how the paving process works.

This starts with learning what asphalt is and what it’s made of.

Core Ingredients of Asphalt

The specific makeup of asphalt pavement can vary from product to product.

It usually includes the following:

• Aggregates: solid mineral materials of varying sizes
  • Crushed stone
  • Gravel
  • Sand
  • Recycled materials
• Asphalt Binder: the sticky substance holding the aggregates together
• Bitumen: a black, viscous substance derived from the oil refining process
• Additives: extra ingredients that give the pavement specific properties
• Polymers: reduce rutting and increase weather resistance
• Rejuvenators: restore performance of old asphalt binder
• Anti-stripping additives: protect against moisture damage
• Polyphosphoric acid (PPA): increases resistance to high temperatures
• Mineral Fillers: optional fine-grain minerals that change the properties of the pavement
• Lime
• Cement
• Diatomite

Most asphalt pavement is made of about 95% aggregates and about 5% bitumen. 

When they’re used, additives and fillers make up a very small percentage of the product.

Common Uses

Asphalt pavement is most commonly used to build roads and driveways.

Here are just a few of the many other uses for asphalt:

• Runways
• Racetracks
• Tennis courts
• Water reservoirs
• Bike paths
• Roofing
• Bridge decks

Benefits

Asphalt is one of the most popular paving materials for good reason.

Here are some of the key benefits of using asphalt pavement:

• Durable and flexible: Asphalt adapts to ground movements and changing temperatures without cracking.
• Weather resistant: Asphalt is resistant to rain, snow, heat, and cold.
• Absorbs the impact of traffic: Vehicles that drive on asphalt pavement are less prone to wear and tear.
• Easy to maintain: Although cracks may form in asphalt after extreme weather events or years of frequent use, it tends to have a long lifespan compared to other materials.

The Crafting Process

The mixing process varies depending on the type of asphalt pavement being manufactured.

Considerations When Making Asphalt Mixes

Climate is the most important consideration when making asphalt mixes. Asphalt pavement that needs to withstand hot temperatures will have different properties than asphalt pavement used in cold climates.

The type and volume of traffic is another key factor. Some asphalt pavement products are made to handle much heavier and more frequent traffic than others.

Sourcing and Preparing the Materials

Aggregates for asphalt pavement usually come from quarries. The specific types of aggregates are chosen based on the desired properties of the asphalt pavement being produced.

The manufacturer dries out the aggregates by placing them in a drum dryer.

Then, they heat up the bitumen to allow it to mix easily with the aggregates.

Mixing the Ingredients

The aggregates and bitumen are combined in an asphalt mixing plant. Sometimes, chemical additives are included in the mix to increase flexibility or durability.

Once finished, the asphalt mix is kept in a heated silo while it awaits transport.

Finally, the hot asphalt mixture is transported in specialized trucks to the construction site.

Environmental Considerations

There have historically been some concerns about the environmental impact of asphalt paving. 

As everyone works toward a green future, it’s important to understand the environmental risks and the efforts being made to reduce them.

• Asphalt is associated with oil production, a process known to be harmful to the environment.
• Asphalt absorbs heat and re-releases it at night, which contributes to the urban heat island effect.
• Asphalt pavement can heat up stormwater, which affects water quality.
• Workers exposed to asphalt’s fumes can experience headaches and rashes and may be at risk for long-term consequences such as skin cancer.

However, manufacturers, construction companies, and regulatory agencies are all working to make asphalt paving a safer process.

• Manufacturers are exploring new mixes for asphalt pavement that increase light reflectance and reduce the urban heat island effect.
• Protective measures for workers recommended by OSHA can reduce exposure to dangerous fumes.
• Asphalt is a 100% recyclable material.
• Reclaimed Asphalt Pavement (RAP) can be put into asphalt mixes and perform just as well as new asphalt.

Types of Asphalt Mixes

There are three main types of asphalt mixes: hot, warm, and cold. All three options have different manufacturing processes and uses.

Quality Control in Asphalt Production

The quality of asphalt pavement makes a significant difference in how long it lasts.

High-quality material will withstand extreme weather conditions and heavy traffic for a long time before showing wear and tear.

Quality control is key during manufacturing. Asphalt manufacturers test the product during each step of the process.

In addition to quality checks by the manufacturer, asphalt pavement is monitored by state and federal agencies.

The Federal Highway Administration’s Turner-Fairbank Highway Research Center (TFHRC) analyzes asphalt samples.

They use a machine called a dynamic shear rheometer (DSR) to test the stiffness of asphalt, which determines the highest temperature the asphalt can handle while maintaining its performance.

The TFHRC tests the asphalt for re-refined engine oil bottoms (REOB) as well. REOB is the residue left when waste engine oil from cars is recycled.

This substance is banned or restricted in many states because it can impact the lifespan of asphalt pavement.

Are You Looking for Asphalt Paving Services? Betz Works Is Here to Help!

Asphalt pavement is a great option for residential driveways. Betz Works has provided asphalt paving services for homeowners in Santa Cruz, Monterey, and Santa Clara Counties for over 65 years.

If you’re looking for a sturdy, safe, and smooth driveway that enhances curb appeal, we’re happy to help.

Contact us today to learn more or request a free estimate.

FAQs

How do I maintain my asphalt pavement?

Sealing can be a great way to maintain your asphalt driveway. It requires reapplication every two or three years, but it will reduce the risk of potholes and cracks and make your driveway easier to clean.

To repair your asphalt driveway, you should first remove all the debris from the crack with a leaf blower or pressure washer. Then, apply the asphalt mix and wait 24 to 48 hours for it to dry.

Is asphalt better than concrete?

Concrete and asphalt both have unique advantages and disadvantages. Asphalt is more cost effective than concrete, but concrete usually has a long lifespan. If you live in a cold climate, asphalt is typically a better option.

What’s the difference between asphalt and blacktop?

Blacktop contains more filler than asphalt, and it tends to be smoother and shinier. However, asphalt is tougher and less porous. Blacktop is often used for less-trafficked areas.