How Is Asphalt Made?
Asphalt is a part of nearly everyone’s day-to-day lives. From the roads we drive on, the sidewalks we walk on, and the highways we use to commute to and from work, asphalt can be found everywhere.
Not only is asphalt one of the most commonly used pavement materials, but it’s also highly durable, easy to repair, and can be recycled to be used for various other pavement and construction projects. But have you ever wondered about the process of how asphalt is made?
In this article, we’ll examine how asphalt is made, the manufacturing process used to create asphalt, and the various types of asphalt that can be used for a wide range of needs.
Continue reading below to learn everything you need to know about asphalt and discover why South Central Sealing & Paving is Wichita’s preferred choice for high-quality asphalt maintenance services.
The Asphalt Manufacturing Process
Asphalt is a long-lasting paving mixture made of aggregates, hydrated lime, binders, fillers, and many layers of unbound and bituminous-bound materials used to bind aggregate together. The black, sticky, semi-solid petroleum product provides a smooth, long-lasting surface for driveways, sidewalks, tennis courts, playgrounds, airport runways, and parking lots.
Although asphalt pavement is typically made up of 5% asphalt cement and 95% aggregate, many manufacturers add additives and polymers to the mixture to create a stronger bond and greater flexibility. Additionally, the ingredients used to produce asphalt may vary slightly depending on the location where the asphalt will be placed.
Despite its widespread use, most people are unaware of how asphalt is made. Let’s take a closer look at the properties of asphalt and its manufacturing process.
The asphalt manufacturing process begins with rapidly heating crude oil for distillation. Once heated, the crude oil is transferred to a distillation container, where a series of condensing and cooling mechanisms separate the more volatile and lighter-weight components called fractions.
The crude is subsequently separated to produce gasoline, diesel fuel, kerosene, and other petroleum products. Any remaining deposit from the distillation process is used as “topping” crude, which is utilized to make heating oil or other products, such as asphalt.
Asphalt can be “cut back” using a volatile ingredient to produce a more flexible product at lower temperatures than regular asphalt. When cut-back asphalt is used for paving or construction, the volatile element evaporates when exposed to air or heat, leaving only the solid asphalt.
Asphalt can also be emulsified to produce a liquid that can be readily pumped via pipes, mixed with aggregate, or sprayed through nozzles. During this process, asphalt is ground into globules 5 to 10 microns in size and mixed with water. After that, an emulsifying agent is added to reduce the tendency of the asphalt and water to separate.
Hardened asphalt is occasionally crushed to make powdered asphalt, and the asphalt is pulverized and then passed through a series of sieves to produce granules of uniform size. Powered asphalt is typically mixed with oil and aggregate. Heat and pressure are also used to combine the powder, aggregate, and oil to gradually harden the mixture to a cement-like consistency.
During the air-blowing process, asphalt is heated to 500° Fahrenheit, and air bubbles are blasted into the liquid for several hours to produce a substance that softens at a higher temperature than what is used for asphalt paving. As a result, when cooled, the asphalt remains liquid.
Asphalt Quality Control
Due to the various oil resources and refining technologies used to produce crude oils with significantly varying properties, crude petroleum oil’s inherent qualities significantly impact the quality of asphalt cement. As a result, three crucial aspects must be considered when using asphalt for construction purposes to ensure the highest quality asphalt surface.
Asphalt’s consistency or viscosity changes with temperature, and asphalt is graded based on consistency ranges at a standard temperature. As a result, a standardized viscosity or penetration test is commonly used to measure the consistency of paving asphalt.
As it leaves the refinery, asphalt cement must be free of water or moisture. Thus, asphalt’s purity must be evaluated to measure its ability to be pulled, dragged, or distorted. A conventional asphalt cement briquette formed under standard conditions and dimensions is pulled at a normal temperature until it breaks under stress to determine elasticity.
While asphalt is moisture-free after production, a delivery vehicle’s holding tank may contain trace amounts of water. When heated over 212° Fahrenheit, the moisture in the asphalt may cause it to foam, posing a safety issue. In the event of a spark or flame, the foam will emit fumes that can flash or ignite all at once.
The Various Types of Asphalt
Because of the various applications of asphalt, the mixture must have sufficient stiffness and deformation resistance to cope with each application’s applied pressure. Things, such as the amount of traffic, the number of heavy vehicles, environmental temperature, and weather conditions, must be taken into consideration to ensure the asphalt can withstand the varying pressures exerted on the surface.
Asphalt mixtures are classified into three types: warm, hot, and cold. The various types of asphalt can be manufactured to create even more distinct combinations to better fit the objectives of a project’s end goal.
Hot Mix Asphalt (HMA)
Hot mix asphalt, or HMA, refers to asphalt mixtures that are heated and poured at temperatures ranging from 300° to 350° Fahrenheit. Due to its flexibility, weather resistance, and ability to repel water, this type of asphalt is the most commonly utilized in the United States for highways, interstates, and roads.
Cold Mix Asphalt (CMA)
Cold mix asphalt is produced without heating the aggregate, resulting in a lower production cost, and it is typically recommended for less frequently used roads. CMA relies on bitumen emulsified in water that breaks down either during compaction or mixing, producing the aggregate coating. The water then evaporates, and the asphalt’s strength increases during the curing time.
Warm Mix Asphalt (WMA)
Warm mix asphalt is produced without heating the aggregate, resulting in a lower production cost, and it is typically recommended for less frequently used roads. WMA relies on bitumen emulsified in water that breaks down either during compaction or mixing, producing the aggregate coating. The water then evaporates, and the asphalt’s strength increases during the curing time.
Wichita’s Number One Choice for High-Quality Asphalt Paving and Maintenance Services
Asphalt is one of the oldest engineering materials known to man, dating back to 2600 B.C. Because of its strength, durability, and low cost, asphalt is one of the most frequently used materials to construct everything from irrigation systems to highways. Although asphalt manufacturing is a complex and precise process, it can last for decades if professionally installed and properly maintained.
Are you getting ready to start a new project and want to work with a team of asphalt experts? Look no further than South Central Sealing & Paving.
At South Central Sealing & Paving, we aim to ensure your asphalt surface is built to last. With over 30 years of experience, cutting-edge equipment, and extensive industry knowledge, we’re proud to offer our Wichita customers a wide range of asphalt paving and maintenance services.
From sealcoating and slurry sealing to pothole repair, crack, and joint sealing, our asphalt experts know what it takes to deliver high-quality solutions on time and within budget.
We’re honored to be Wichita’s number one asphalt paving and maintenance company, and we can’t wait to learn more about how we can assist you. Contact us today to learn more about our extensive services and speak with one of our experts about how we can help you.