What is Hot Mix Asphalt?
Hot mix asphalt (HMA) is a combination of approximately 95% stone, sand, and gravel bound together by asphalt cement, a petroleum product. It is heated and mixed at asphalt plants, then transported to the construction site for paving. Asphalt is the most common paving material for roads, driveways, and parking lots due to its durability, cost-effectiveness, and ease of maintenance.
Asphalt density varies by mix type but typically ranges from 140-150 pounds per cubic foot (2.24-2.40 tonnes per cubic meter). This calculator uses a standard density of 145 lb/cu ft, which is typical for dense-graded hot mix asphalt.
Asphalt Calculation Formula
Recommended Asphalt Thickness
| Application | Minimum Depth | Recommended Depth |
|---|---|---|
| Residential Driveway | 2" | 3" - 4" |
| Parking Lot (light traffic) | 2.5" | 3" - 4" |
| Parking Lot (heavy traffic) | 3" | 4" - 6" |
| Municipal Road | 3" | 4" - 8" |
| Highway | 4" | 6" - 12" |
| Overlay / Resurfacing | 1.5" | 2" - 3" |
Paving Tips
- Always prepare a proper aggregate base (4-8 inches of compacted gravel) before paving.
- Order 5-10% extra material to account for waste and compaction.
- Asphalt should be compacted to 92-96% of theoretical maximum density.
- Do not pave when temperatures are below 50°F (10°C) or when rain is expected.
- Seal coat new asphalt after 6-12 months and every 2-3 years thereafter.
Frequently Asked Questions
How many tons of asphalt do I need for a driveway?
A typical two-car driveway (20 ft x 50 ft) at 3 inches thick requires approximately 10-11 tons of asphalt. Costs range from $1,000 to $1,500 for material alone, plus installation labor.
How much does asphalt weigh per square foot?
At 1 inch thick, asphalt weighs approximately 12 pounds per square foot. At the standard 3-inch driveway thickness, it weighs about 36 pounds per square foot.
How long does asphalt last?
Properly installed and maintained asphalt can last 15-25 years. Factors affecting lifespan include traffic volume, climate, drainage, base preparation quality, and maintenance practices like seal coating and crack filling.