Matthew,

I did a web search to attempt to determine the density of asphalt and on the SImetric site I found

• Asphalt, crushed 721 kilograms per cubic meter
  
  
• Concrete, asphalt 2243 kilograms per cubic meter

One is three times as heavy as the other so the type of asphalt is extremely important.

Once you know the density you can have Google do the calculations, even if the density is in metric units. I'll illustrate with the crushed asphalt density.

Type 12 cubic yards in cubic meters into the Google search engine at it returns 12 (cubic yards) = 9.1746583 cubic meters. Multiply by the density (721 kg/m³) to find the weight in kilograms (6614.929 kilograms). Finally type 6614.929 kilograms in tons into Google to get a response of 6 614.929 kilograms = 7.29171106 short tons.

I hope this helps,
Penny