What is asphalt made of?
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What is asphalt made of? Two big parts: aggregate (crushed stone, sand, and fines) and asphalt binder (bitumen). Ask what is asphalt made out of or what is in asphalt, and the short list is the same — rock for strength, binder for glue, mixed to a design the plant follows.
Typical hot-mix asphalt is mostly aggregate by weight. Binder is a smaller percentage, but it is what holds the stone together after compaction. Exact grades and percentages are set for traffic and climate; your paving crew or plant can name the mix they are delivering.
Estimate how many tons you need →Aggregate: the bulk of the mix
Aggregate sizes are controlled so the mix packs well and wears evenly. Surface courses for driveways often use a finer texture than a coarse base or binder course underneath. Dirty or poorly graded stone is a quality problem — plants wash and screen for a reason.
Binder: the black glue
Asphalt cement (bitumen) coats the aggregate when both are hot. Performance grades (PG) match temperature swings in your region. Homeowners rarely buy binder by the drum; you buy finished mix by the ton.
What else might be in asphalt?
- RAP — reclaimed asphalt pavement (millings) blended into new mix where allowed.
- Additives — polymers or other modifiers in some specialty mixes (ask the plant if it matters for your bid).
- Not usually in driveway HMA — coal tar, random construction debris, or roofing waste mixed in by accident. Those are different streams.
How the plant combines them is covered in how is asphalt made. For a plain definition of the finished product, see what is asphalt.
Cold patch and sealcoat are different recipes
Bagged cold patch is a repair product with its own binder system so it works cooler. Sealcoat is a thin surface treatment, not structural mix. Neither answers “what is in asphalt” for a full plant pave.
Base stone under the asphalt
Crushed stone base under the pavement is a separate layer. It is not “in” the asphalt mix, but failed base ruins good mix. Size base with the asphalt base calculator when you rebuild from the ground up.
Bottom line
What is asphalt made of? Mostly crushed aggregate plus asphalt binder, often with recycled pavement blended in. What is in asphalt on your driveway is that engineered mix — not gravel alone, and not roofing shingles. Use the calculator to turn area and thickness into tons once you know the product.
FAQ
Is asphalt made of oil?
The binder is a petroleum-derived product (bitumen). The bulk of the pavement by weight is still stone aggregate.
Does recycled asphalt count?
Yes — RAP is commonly used in new mix when the design allows. Loose millings used as a driveway surface are a different use case.
Can I mix asphalt at home?
Not like a plant. Homeowners use bagged patch products for small repairs. Full driveways need plant hot mix and compaction equipment.