If you want to see the exact process of making the paving asphalt, you can check the video from the popular Discovery Channel show “How it’s Made”, below:
Asphalt cement is a byproduct of the crude petroleum refining process. It is a black liquid substance that is the most important ingredient in creating the asphalt, although it makes up only 5% of the asphalt mix, it makes it malleable and possible to blend to a form that is used to pave roads, driveways, etc.
The other four ingredients of the asphalt mix are:
All of the above makes up for 95% of the mix, depending on what the asphalt will be used for.
The process starts at a paving plant’s quarry. Big boulders of granite are blasted off the rock walls and then collected by heavy machinery operators to transport them to trucks that will take the rock material to paving plant nearby.
Boulders are dumped to a primary crusher, the big and powerful machine that can turn them into smaller pieces.
The machine empties the load on a mobile conveyor belt that transports material to the outdoor storage area.
Next, another conveyor belt transports the crushed material to the screening building where it is classified by size, as the rock avalanche goes down the incline set of screens allows only 10cm rocks to drop in.
Bigger elements go to the secondary crusher that reduces the side of the rock to 10cm or less just to send them to the tertiary crusher that further reduces rocks size to 2cm or less.
After the process, the materials can be segregated into four piles:
Materials are taken from piles and put into feed bins, separate containers used during the process of manufacturing the asphalt.
How much of given material is going to be used depends on what needs to be paved, insulation or roofing shingles will have different proportions of materials than asphalt used for paving roads.
The final process of making the asphalt starts with a set of conveyor belts that transport a certain amount of given ingredient from the feed bins to the main collecting belt that leads to a dryer.
To remove all humidity the materials must stay in the dryer for 1 minute.
This is a crucial step to make sure that the materials will bond together with liquid asphalt cement.
After drying, a screening equipment is used once again to make sure that amount of the used materials is correct and will create a high-quality end product.
To make sure that the mix will combine smoothly, the mixer blends the dried and thoroughly selected material.
The last step in making the asphalt is to pour hot asphalt cement into the mix and let it bind the ingredients in about 30 seconds.
Finally, the asphalt is ready to be dropped on the truck and taken to the paving site. On the site, the paving machine will spread the asphalt on a road bed, then a compactor roller will pack it down to create nice even road.