ELI5: How asphalt is made?

Imagine your mom baking a cake. Asphalt is kind of like that, but instead of flour and sugar, we use rocks and sticky stuff!

The sticky stuff is called bitumen. Think of it like super thick, gooey honey, but black. It's left over after we take oil from the ground and make things like gasoline for cars.

Here's how we make the asphalt for roads you drive on:

• Step 1: Get the ingredients. We need lots of small rocks, sand, and gravel. These are called aggregate. We also need the black, sticky bitumen.

• Step 2: Heat it up! We heat the rocks and sand really hot in a big oven-like machine. This dries them out and makes them easier to mix.

• Step 3: Mix it all together! Now, the hot rocks and sand go into a big mixer, like a giant cake mixer. We pour in the hot bitumen. The bitumen coats all the rocks and sand, making a sticky, black mixture. The recipe, or mix design, tells us exactly how much of each ingredient to use.

• Step 4: Load it up! The hot asphalt mixture is loaded into big trucks.

• Step 5: Pave the road! The trucks take the hot asphalt to where we need a new road or to fix an old one. Special machines called pavers spread the hot asphalt evenly on the ground.

• Step 6: Roll it flat! Big rollers, like steamrollers you might see in cartoons, drive over the hot asphalt to squish it down and make it smooth and strong.

• Step 7: Let it cool! Finally, we let the asphalt cool down and harden. Once it's cool, you can drive on it!