Compute Bituminous Material
Several methods are used to calculate the amount of
hot-mix material required for paving projects; however,
when the weight of a hot-mix per square yard or cubic
foot is not known, two equations are used in the NCF to
compute the number of tons of asphalt required for a
project. These equations are as follows:
Equation 1
= Percent of Tons + Tons = Tons Required
Where:
L = length of project in feet
W = width of project in feet
D = depth or thickness of compacted mat. You
must change inches into feet by dividing
the number of inches by 12 (inches in 1
foot). For paver screed height, add 1/8
inch for each inch of the mat to be paved.
(Example: for a 2-inch mat, two blocks of
wood 2 1/4 inch thick will be required to
set under the screed.) The blocks must be
thicker than the finished compacted mat
to allow for additional compaction by
rollers
146 = This number represents the approximate
weight of 1 cubic foot of compacted
hot-mix asphalt. This number can vary
from 140 to 160 pounds; however,
146 pounds equals the 110 pounds per
square yard per 1-inch depth of asphalt
used in the second equation for figuring
tons require for asphalt. (See table 8-5.)
WF = Waste factor equals 5% or .05, or 10% or
.10, depending on the experience of the
screed operators and handwork required
on the project
2,000 = 2,000 pounds is equal to one ton;
therefore, you must divide the total
weight of material by 2,000, giving tons
required.
8-31
