There’s no denying that asphalt is the king of road construction. As shown in this video, it's used in a whopping 94% of all roadways in the United States. The material is a mix of various aggregates and some liquid asphalt glue that holds everything together.
These aggregates make up around 95% of the mix. They contain stone, sand, and even some reclaimed products.
The type of stone used can actually vary, depending on the location. It's all about using what's available.
Now, here's where things get interesting. The size of these aggregates can make a big difference in the quality of the pavement. If asphalt contractors go with larger aggregates, they'll build a stiffer pavement that's not so flexible. On the other hand, if they use more fine aggregates, the road surface will be more flexible.
Then there’s liquid asphalt binder. This stuff is like a super adhesive that holds all the different layers of a road together. It comes from the heavy components of crude oil. Manufacturers take the thick and gooey parts of crude oil and refine it to create this sticky, yet flexible substance.
It’s possible to tweak the properties of this liquid asphalt binder to suit different road conditions. They do this by adding polymers and other additives to the mix. These little extras can make the binder more resistant to cracking in cold weather or more flexible in hot climates..