What is asphalt?
Asphalt is a composite: mineral aggregate glued together with bitumen. By weight it is roughly 95% crushed stone, gravel and sand, and about 5% bitumen — the heavy black petroleum fraction that binds it. That ratio explains most of what asphalt does, including what it weighs, why it has to be compacted hot, and why it cools rather than dries.
What it's made of
Aggregate is the structure. It is a deliberately graded blend — coarse stone, fine sand, and mineral filler — proportioned so the particle sizes interlock and leave as few voids as possible. A well-graded mix carries load through stone-on-stone contact; the binder is not doing the structural work.
Bitumen is the glue. At around 5% by weight it coats every particle in a film thin enough to measure in microns, holding the aggregate together while remaining flexible enough to tolerate traffic and temperature swings. It is a petroleum product, distinct from tar, though the two names get used interchangeably in casual speech. Most modern mixes also includereclaimed asphalt pavement — old road milled up and recycled into new mix, which is why asphalt is among the most recycled materials in construction.
How it's made and laid
At a hot mix plant, aggregate is dried and heated, then combined with hot liquid bitumen and mixed until every stone is coated. The mix leaves the plant at around 150 °C and is trucked hot to site — which is why delivery distance matters, since a load that cools too far cannot be compacted properly. A paver spreads it, and rollers compact it while it is still hot.
Compaction is the whole game. It drives out air voids and turns a loose mat into a dense, effectively waterproof pavement. Under-compacted asphalt lets water in, and water in a pavement is what produces potholes after the first freeze. It is also why the thickness you order against is thecompacted thickness — loose mix occupies noticeably more depth than the finished layer.
What asphalt weighs
Compacted in place, hot mix asphalt runs about 145 lb per cubic foot — around 3,915 lb, or 1.96 US tons, per cubic yard. TheAsphalt Institute publishes the range as142–148 lb/ft³ and recommends ordering against the top of it so a load does not come up short.
The rule of thumb worth remembering: at 145 pcf,one ton covers about 83 square feet at 2 inches thick. Halve the thickness and you double the coverage. You will also see the same rule quoted as "about 80 square feet", and both are right — 80 is what you get at the heavier 148 lb/ft³ the Institute recommends ordering against, 83 at the145 lb/ft³ planning figure. Order to the smaller coverage number and you will not be short. Ourasphalt calculator does this properly for your dimensions, and thedensity reference shows the source quoted verbatim alongside every other figure we use.
Asphalt doesn't dry — it cools
This is the most common misunderstanding about new paving, and it changes what you should expect. There is no water in hot mix asphalt, so nothing evaporates. What you are waiting for is heat to leave the mat. In mild conditions that is roughly 24 hours before normal car traffic; in hot weather it takes longer, because a warm mat sheds heat more slowly — pavers often say 48 to 72 hours in a heatwave.
Separately and much more slowly, the binder continues to harden overmonths. That is why a driveway that feels solid can still take an impression from a motorcycle stand, a trailer jack or a wheel pivoted on the spot weeks after laying. For the first season: spread out where you park, keep turning wheels rolling rather than twisting them stationary, and put a board under anything that concentrates weight onto a small point.
Asphalt and concrete are different materials
They are easy to confuse because both are aggregate plus a binder, but the binder changes everything. Concrete uses cement, which reacts chemically with water and sets rigid — it genuinely cures, and it cracks in slabs with joints. Asphalt uses bitumen, which stays viscous and flexible, so the pavement bends slightly under load and can be resurfaced in a layer rather than broken out. Flexible also means softer in heat, which is the trade-off.
A note on what we don't publish: the most-searched asphalt questions are about installed cost per square foot. We deliberately don't answer those with a number, because the figure is dominated by labour, haul distance and site access and varies far too much for a national average to mean anything. What we can give you exactly is the tonnage — price that locally.
Frequently asked questions
What is asphalt?
Asphalt is a composite paving material: mineral aggregate — crushed stone, gravel and sand — bound together by bitumen, a heavy black petroleum product that acts as the glue. By weight it is roughly 95% aggregate and 5% bitumen, which is why its density tracks the stone in it. The name is used loosely for both the binder alone and the finished pavement; in the trade the pavement is usually called hot mix asphalt, or HMA.
What is asphalt made of?
Two things: aggregate and bitumen. The aggregate is a graded blend of coarse stone, fine sand and mineral filler chosen so the particle sizes interlock and leave few voids. The bitumen — about 5% by weight — coats every particle and holds the structure together while staying flexible. Many mixes now also include reclaimed asphalt pavement, milled from old roads and recycled straight back into new mix.
How is asphalt made?
At a hot mix plant the aggregate is dried and heated, then combined with hot liquid bitumen in controlled proportions and mixed until every stone is coated. It leaves the plant at around 150 °C, is trucked hot, spread by a paver, and compacted by rollers while still hot. Compaction is the critical step: it is what squeezes out air voids and turns loose mix into a dense, waterproof pavement.
How long does asphalt take to dry?
Asphalt does not dry — it cools. There is no water to evaporate, so what you are waiting for is the mat to lose heat and stiffen. That takes roughly 24 hours before normal car traffic in mild conditions, and longer in hot weather because it sheds heat more slowly. Full curing, as the binder hardens over time, takes months, which is why a new driveway can still scuff under a turning wheel or a motorcycle stand weeks later.
Can you drive on fresh asphalt?
Wait about 24 hours for cars in mild weather, and longer in heat — a paver will often say 48 to 72 hours to be safe on a hot week. Even then, treat it gently for the first few months: avoid parking in exactly the same spot, keep sharp-turning wheels moving rather than pivoting on the spot, and put boards under trailer jacks, bike stands and anything else that concentrates weight on a small area.
How much does a cubic yard of asphalt weigh?
About 3,915 lb — roughly 1.96 US tons — at the standard in-place density of 145 lb per cubic foot. The Asphalt Institute publishes a range of 142–148 lb/ft³, and recommends using the top of that range when working out tonnage to order so a load does not come up short.
How thick should an asphalt driveway be?
A residential driveway is typically 2 to 3 inches of compacted asphalt over 6 to 8 inches of compacted aggregate base; heavier traffic and softer ground want more of both. The base does most of the structural work — a thick asphalt layer over a poor base still fails. Note that the thickness that matters for ordering is the compacted thickness, which is what our calculator expects.
About these numbers
The density figures and the ordering recommendation come from the Asphalt Institute, quoted verbatim on ourmaterial density reference and rendered onto this page from the same tested data theasphalt calculator computes with, so the two cannot disagree — read how CubicMath works. The mix proportions, plant temperature and traffic-timing figures are standard industry practice rather than a single published spec, and are described as typical for that reason; your paving contractor's instructions for your job outrank them. Building the base underneath? Thegravel calculator handles that layer.