Last Updated on December, 2024
Despite its long existence, many people are unaware of asphalt -that is, until they need to repair small cracks in their driveway.
This predominant material is mainly used in road construction, pavement and surfaces such as roads, parking lots, and airports.
Asphalt is a composite material that is made with crushed stone, sand, gravel, and a dark-coloured liquid component called Bitumen, and a binding agent.
A regular asphalt pavement consists of layers of unbound and bitumen-bound materials that act as a base for the asphalt concrete poured on top.
Quick Summary
- Asphalt is a composite material primarily used in road construction, consisting of crushed stone, sand, gravel, bitumen, and a binding agent. It is widely applied in roads, parking lots, airports, and other infrastructure projects.
- There are different types of asphalt, including Hot Mix Asphalt (HMA), Warm Mix Asphalt (WMA), and Cold Mix Asphalt. Each type has specific properties, such as temperature requirements, energy consumption, and application methods, making them suitable for various project needs.
- Asphalt is durable, cost-effective, and environmentally friendly, offering benefits like improved skid resistance and reduced surface water risks. However, it requires regular maintenance, and its production can negatively impact the environment due to high temperatures and emissions.
How is Asphalt Produced in an Asphalt Plant?
Manufacturers decide which type of asphalt paving and ingredients are required based on the scale of the project and the environment. Asphalt mixtures vary for projects in different locations due to temperature fluctuations.
A hot asphalt mixture is a pavement mixture made by combining hot liquid asphalt with a heated aggregate in an asphalt production plant. This can be made in a factory or a mobile mixing plant.
Different Types of Asphalt
Based on the various requirements of a project, different types of asphalts are used with varying levels of flexibility and strength.
Hot Mix Asphalt (HMA)
Hot mix asphalt is used on highways and city streets due to its flexibility and water-repellent nature. The average temperature of a hot mix asphalt is between 150℃ – 180℃. This hot mix is loaded into trucks directly or stored in heated silos until it is needed.
Warm Mix Asphalt (WMA)
Warm mix asphalt concrete is produced at a temperature of 20 – 40℃ below that of HMA. Significantly less energy is used in the production of warm mix asphalt, with fewer fumes emitted because of its lower temperature.
The low maintenance in WMA allows for better working conditions for the workers during paving.
Cold Mix Asphalt
Cold asphalt mixes are made by using bitumen blended with water. It breaks during the compaction or mixing stage, hence producing the coating of the aggregate without the heating. Once left to cure, water evaporates, leaving the mix stronger.
Due to lower temperatures cold mix asphalt is much more affordable and operator-friendly. This mix is also convenient, as it can be packed into bags and sold at stores.
Different Uses of Asphalt
Asphalt is mainly used to construct infrastructure such as road surfaces, parking lots, bicycle lanes, highways, airport runways, and pavements.
The benefits of asphalt’s durability and its smooth surface allow it to be used for recreational purposes such as playgrounds, bicycle paths, running tracks, and tennis courts.
Benefits and Drawbacks of Asphalt Pavement
A pavement, road, or parking lot made from asphalt significantly improves accessibility to greater locations. Asphalt is cost-effective due to its low initial costs, durability and speed of construction.
Due to its reusable nature and durability, it can be built without having an expiry date.
Asphalt is also environmentally friendly, as bitumen is made from recycled materials. Reclaiming asphalt is just as valuable in paving, thereby being sustainable and cost-effective, as it reduces the need for new materials.
Asphalt pavements provide skid resistance to the user, which gives better vehicle traction and hence minimises the chances of an accident, making it much safer for the driver.
Asphalt types like porous asphalt surfaces also distribute and drain surface water, reducing the risk of aquaplaning and increasing visibility for road users.
However, regular asphalt maintenance is required, and if left forgotten, it may lead to potholes and cracks forming, harming users. While asphalt has a steady lifespan, it is shorter than alternative pavements like concrete.
There is also a negative environmental impact on asphalt production and transportation. The high temperatures and fumes emitted by the constant reheating of HMA to keep it ready for use can cause air pollution.
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Installation and Maintenance of Asphalt
The production process and installation of asphalt is quick and easy, since asphalt doesn’t have a long curing process. Drivers can use the new asphalt surface almost immediately.
After cleaning out the crack, apply the crack filler repair material. Keep in mind that multiple layers may be needed.
For a road surface, the top layer applied is the surface course, the second layer is the binder course, and the lower layer is the base course material. The binder is used to combine the aggregates to form a cohesive mixture.
For pavement cracks that are deeper than 2 inches, use finely crushed sand before adding the asphalt. Smooth out the crack to ensure there aren’t any air bubbles, and allow it to dry thereafter.
Extreme heat and harsh weather conditions are also factors that can soften and deform asphalt. It is essential to maintain an asphalt driveway with crack filling regularly to keep it in good condition.
Oil, grease, gas, salt, and transmission fluid can break down an asphalt pavement and can cause cracking. Driveways should be sealed every three years to prevent oxidation and crumbling.
