How do I calculate the percentage of asphalt in a mix?
The amount of asphalt cement in an asphalt concrete mix is based upon the total weight of the mix including the stone (aggregate) and the asphalt. In the case of cold mix made with emulsion, the asphalt cement is the amount left after the water has evaporated out.
The percentage of asphalt is:
% asphalt in mix = weight asphalt / total weight
The weight of the asphalt is the gallons of converted to pounds times the percentage of asphalt in the emulsion. Using just asphalt, as in hot mix, the percentage would be 100%. For emulsions you should check with supplier, but the range is typically 55-70% asphalt.
weight asphalt (lbs) =
gallons asphalt emulsion per ton * 9.4 lbs/gal * %asphalt in emulsion
The total weight of the mix is the weight of the asphalt plus the weight of the stone (aggregate). Be sure to convert the weight of the stone to pounds before adding the weight of the asphalt.
total weight = weight asphalt + weight stone
This attached spreadsheet shows the calculations. Just fill out the cells in Orange and the calculations will be done in the grey cells.
Asphalt Paving Principles (pdf)
CLRP workshop manual