You likely see asphalt on a daily basis. Many driveways, roads, parking lots, and even walking trails are made of asphalt. This is because asphalt is the perfect material for areas where smooth flat surfaces are the solution and the sun is a factor in durability. Have you ever wondered how asphalt came to be or how they are manufactured to look like the end products you see on those surfaces?
This article will help you understand how asphalt is made – from the manufacturing process to how it is used in pavement.
Understanding Asphalt and What It’s Made Of
In oil refineries, petroleum from oil wells is separated into various factions. The heaviest part of petroleum is the asphalt in its natural state. This is then modified for malleability and consistency. For malleability, the asphalt is modified by adding a cutting agent. For consistency, the asphalt is either pulverized or emulsified. When used for paving, asphalt undergoes a mixing process. The mixing is either done in a drum mix plant for large output or in a batch plant for small output needs.
In general, the composition of asphalt is about five percent asphalt cement and 95 percent aggregate. The asphalt cement is the glue that binds the aggregate together.
Depending on the climate in the area and surface requirements, the aggregate varies. Essentially, you can find small rocks and sand mixed into the aggregate.
When used in pavements, large and smooth rock aggregates are placed in the lower section. Meanwhile, finer aggregates are used on the surface. Other additives may also be added for improvement, such as hydrated lime as a further bonding agent. Polymers can also be used to enhance flexibility. Sometimes, tiny particles called “fines” are also added to extend the pavement’s lifespan.
How to Get the Right Asphalt Mix
The right mix of asphalt is the key to a long-lasting pavement. There are a few ways of mixing asphalt, but the hot and cold mix is the most popular. The hot-mix asphalt is made by heating the aggregates, decreasing the viscosity of the building agents. The heating process turns the mixture into a more fluid substance. The asphalt is mixed at about 200 to 350 degrees Fahrenheit.
The hot-mix asphalt is then dried to remove any moisture. This mix is so-called not only because of the mixing process but because the mixture must remain warm while being paved and compacted onto the roads, parking lots, or driveways. This is also why asphalt paving is usually done during the summer.
On the other hand, the cold-mix asphalt is made of materials that keep the mixture soft and repel water. The mix is composed of a quarter-inch chip and proprietary oil. This asphalt doesn’t require heating. Instead, additives in the oil are necessary to keep the mixture soft and allow for easy asphalt repair in any type of weather.
Cold-mix asphalt stays soft and can significantly repel water even in cold and wet weather. Thus, making it the perfect mixture to use in pavement repairs during early spring or winter. No matter which type of mixture is used, proper control and transportation are necessary for keeping its viscosity, consistency, and purity.
Environmental Impact of Asphalt Manufacturing
If you are concerned about the impact of asphalt manufacturing on the environment, there’s no need. Throughout this process, emissions are rigorously monitored and controlled to reduce impact. There is the equipment used to re-collect dust and particles so they can be reused in the heating process.
Aside from increasing the efficiency of the heating process, this eliminates the possibility of being emitted to the environment. Asphalt can also be recycled and reused. Every year, 90 million tons of asphalt are recycled into new asphalt.
Benefits of Asphalt Pavements
There are many benefits to using asphalt instead of concrete on roads and pavements. First, asphalt surfaces are safer, quieter, and smoother for driving even at higher speeds. Splashing and spraying during the rainy season are also reduced on asphalt roads. Thus, also reducing the risks of collisions.
Asphalt is also low-cost and more durable compared to concrete. Asphalt is more cost-effective, will last longer, and will require less maintenance. Asphalt roads also help lower vehicle maintenance costs because of the reduced wear and tear. And since it is designed for various traffic volumes, asphalt pavements can last up to 20 years.