 |
1. How is an asphalt pavement built?
|
 |
The pavement is built in layers. The first step is to remove topsoil and compact the earth. Then, a base that will help to carry the load is placed and compacted. (The base may be constructed solely of stone, or it may include both stone and asphalt.) Then, two or more layers of hot mix asphalt are placed and compacted.
For further information on how asphalt pavement is built, please click here. |
|
| [ top ] |
| 2. How is Hot Mix Asphalt is Produced? |
|
In its most basic form, Hot Mix Asphalt (HMA) is produced at the plant by drying and heating the aggregates and then mixing and coating them with warmed liquid asphalt. However, this process is a very intricate process utilizing state of the art equipment to ensure the highest quality HMA.
For further information on how Hot Mix Asphalt is produced, please click here.
To learn more about this process, you can watch the video below which details the process of making HMA at the plant. There are two versions of this presentation. One involves an HMA plant which gets its aggregates from a pit. The other involves an HMA plant that gets its aggregates from a quarry. This presentation shows you how the blasts are controlled to allow excavation of the aggregates.
To learn more about Hot Mix Asphalt, please click here. |
|
| [ top ] |
3. How thick does the asphalt need to be for a road?
|
|
That’s an engineering decision, based on what kind of stresses the pavement must withstand (trucks vs. cars) and other factors such as soil conditions and climate. It also depends on what materials will be used in the asphalt and what materials might be present in the lower layers of the pavement.
For further information, please click here. |
|
| [ top ] |
| 4. What can asphalt be used for? |
|
The first thing that comes to mind when you hear asphalt is roads. But the versatility of asphalt makes it the ideal material for other applications and locations: from driveways to runways, from the barn floor to the ocean floor.
HMA is also used worldwide as a practical solution to water storage, flood control, erosion, and conservation problems. Asphalt has been approved by the Environmental Protection Agency and used successfully as a primary liner for both sanitary and hazardous waste landfills.
You'll find asphalt all around you in a variety of uses, including:
Transportation - highways, railbeds for transit systems, airport runways
Recreational - running tracks, greenway trails, playgrounds, bicycle and golf paths, racetracks, basketball and tennis courts
Aquatic - fish hatcheris, reservoir liners, industrial retention
pond, sea walls, dikes and groins to control beach erosion
Residential - driveways, subdivision roads
Agricultural - cattle feed lots, poultry house floors, barn floors, greenhouse floors
Industrial - work sites, log yards, ports, freight yards, landfill caps
For more information, please click here. |
|
| [ top ] |
| 5. What is Hot Mix Asphalt? |
|
Source: http://www.wispave.org/contentviewer.aspx?cid=41
Hot mix asphalt (HMA) is high-quality, thoroughly controlled, engineered material. In general, there are two basic ingredients to HMA, aggregates and liquid asphalt.
Aggregates can come in the form of stone, gravel and sand. Which aggregates are used in a given mixture of HMA depends largely what is available locally. It can also be affected by the specifications for the HMA. Generally, aggregates represent about 95% of the total weight of HMA. Aggregates come from either a pit or quarry. A pit is defined as an open excavation where unconsolidated materials are removed for construction, industrial or manufacturing purposes. A quarry is defined as an open excavation where consolidated materials are removed for construction, industrial or manufacturing purposes. In general, quarries require controlled blasting of the consolidate materials.
The remaining 5% is liquid asphalt which is also referred to as asphalt cement or asphalt. Liquid asphalt is a derivative of the crude oil refining process. It is the binder or “glue” in the HMA. Liquid asphalt is one of the heaviest, most viscous parts of the petroleum. This is why it is ideal for “holding” the aggregates together. The two ingredients are mixed together at a plant to make hot mix asphalt. To learn more about how HMA is made at the plant click here. |
|
| [ top ] |
|
|
