“How is asphalt made?” is a common question among homeowners who plan to use this material in their DIY home projects as well as construction companies who regularly use asphalt for their business projects. In this blog post, we will learn what asphalt is and how asphalt pavements are made. Discover what the different types of asphalt are and what base preparation is needed. Finally, find out how much asphalt costs by getting a free estimate for asphalt services in Utah.
What Is Asphalt?
Asphalt is a black or gray material that comes from petroleum. Britannica explains that it is made up of compounds of hydrogen and carbon mixed with smaller amounts of sulfur, nitrogen, and oxygen.
Asphalt concrete, which is a mixture used in construction, is a combination of aggregates, fillers, and binder. Traditional aggregates used in asphalt include gravel, sand, and crushed rock. Some examples of modern, recycled aggregates are demolition debris and construction scraps. Bitumen, a petroleum substance, usually serves as the binder, although bio-based binders are also being developed.
Asphalt is typically used in building, maintaining, and repairing driveways, patios, streets, sidewalks, parking lots, airport runways, and bicycle lanes.
How Is Asphalt Made?
Asphalt is generally made in an asphalt plant, either at a permanent location or a mobile one. An asphalt plant can generate up to 800 tons of asphalt every hour. While the exact procedure may vary depending on the type of asphalt produced, these are the typical steps of the asphalt making process:
- Step 1: The asphalt manufacturer mixes the aggregates. The components of the mixture will depend on the particular requirements of the construction project.
- Step 2: The aggregate mixture is washed and dried.
- Step 3: The asphalt cement or binder is thinned out by heating, emulsifying it in water, or adding a solvent.
- Step 4: The aggregate mixture and asphalt cement are mixed together using industrial mixing machines like pugmills or drums and heated, although certain modern methods are capable of producing asphalt at lower temperatures.
What Are the Different Types of Asphalt?
There are various kinds of asphalt and several factors are considered when creating this construction material. These factors include the amount of asphalt needed, the level of durability or weight load required for the project, whether or not the asphalt project requires the asphalt to be permeable or impermeable to water.
The asphalt needs to be tough and resistant to prevent deformation caused by external pressure. At the same time, it has to be flexible enough to avoid cracking from outside forces. The asphalt must have suitable properties based on the application.
These are the three main types of asphalt:
1. Hot Mix Asphalt
Hot Mix Asphalt (HMA) is heated at temperatures that fall between 302°F and 356°F and should have initial compaction at 220°F-290°F. It is created by heating both the asphalt cement and aggregate while being mixed. It is then laid, and compacted before it cools. It is the most popular kind of asphalt since it is strong enough to withstand wear and tear in high-traffic highways and streets.
2. Warm Mix Asphalt
Warm Mix Asphalt (WMA) is formed at temperatures that are lower by 50°F to 100°F compared to HMA temperatures. The WMA process requires a lower amount of energy so it generates fewer fumes. Since the required temperature is cooler, it allows more time to work the asphalt which allows for longer trucking distances and paving in cooler seasons.
- Cold Mix Asphalt
Cold Mix Asphalt (CMA) can be made without heating the aggregate. Bitumen is emulsified in water, which breaks during the mixing or compacting procedure to generate the aggregate coating. CMA becomes more durable as the water evaporates while the mixture is cured. Cure time is longer than warmer mixes and is appropriate for streets that have low-volume traffic or for pothole repair.
What Are the Various Layers of Asphalt?
There are a variety of layers present in asphalt pavement. These layers are paved on a road base layer that is either bound or unbound.
The surface course is the top layer of the pavement. Its purpose is to create a durable, fairly even surface that is easy to plow, holds up the expected loads and is comfortable for pedestrians and vehicular traffic. The surface course ought to have noise reduction and skid resistance properties. It should be long-lasting enough to survive constant traffic and external pressure with limited cracking. Some examples of a surface course are Asphalt Concrete (AC), Hot Rolled Asphalt (HRA), and Porous Asphalt (PA).
The binder course is the second top layer, just below the asphalt. It must be sturdy and stable.. It is positioned between the surface course and base course to minimize rutting. Stone-on-stone contact, along with the use of stiff or modified binders, contributes to its stable characteristics.
The base course may be the lowest layer besides the subgrade, yet it is a vital component of the asphalt structure. It has the largest aggregate and must be adequate to hold whatever weight load will be applied without sinking.
Get a Free Estimate From Top Job Asphalt
You may be wondering how asphalt is made and which type of asphalt is ideal for your home venture or business construction project. At Top Job Asphalt we are ready to help you choose and use the asphalt that is perfect for your needs. We offer excellent asphalt paving and maintenance services for homeowners, companies and cities in Logan, northern Utah and southern Idaho.
Get a free estimate now to learn how our experienced, skilled team of experts can assist you with your asphalt construction projects.