Use this to good advantage by extending the use of the
Establish a density to be compacted in the pan
tester to become a good AC content tester for field use.
each time. . this is 135 pounds/cubic feet, a value that
is about 95% of optimum for the region that is going to
Some additional hardware is required
use this test. It will vary, of course, for different parts of
a. Metal pan, approximately 16" x 16" x 4".
If the desired density is 135 PCF, and if each inch in
b. Compaction plate...5" x 5" x 1/2" with a rod
the pan represents 0.1481 cubic feet then a one inch
welded to it and a sliding weight to slide on the rod and
layer compacted to 135 PCF would actually weigh 19.99
permit a controlled compaction effort on the plate.
c. Accurate scale to approximately 30 pounds.
135 PCF x 0.1481 CF = 19.993 pounds.
d. Straight edge and a finely graduated metal ruler.
b. Measure out exactly 19.99 pounds of hot AC mix
.. C-clamp to clamp the ruler to the straight edge. The
and dump this into the pan.
straight edge should be approximately twice as long as
the pan's longest dimension.
Spread it around evenly and then compact it down to
a depth of exactly one inch.
A 1/16th inch error in height is equal to a 6% error in
Establish an initial calibration curve in the laboratory.
final compaction. . an error of 8.1 PCF, something not
After that, the same procedure is used in the field to
accepted or calibration work.
establish the desired asphalt content value.
c. Compact a second and third lift in the same
Prepare a sample of asphaltic concrete at a specific
weight each time. This weight will be selected at the
outset and will be used for the initial calibration as well as
Weigh the final pan of material and it should weigh
for all subsequent field tests.
exactly 3 x 19.99 = 59.97 pounds plus tare.
This weight should be approximately 95% of optimum for
d. Set the pan atop the tester shipping case in the
the typical asphalt weights used in the user's locale.
same manner as you would take a standard count.
Round it off to a practical value for ease of preparation
Remove the reference standard from the case.
e. Take several tester moisture readings on the
Initially prepare a sample at a known density, evenly
compacted surface, revolving the tester 900 each time.
compacted in the pan in one inch thick layers.
Record the readings.
Thereafter prepare the sample in the same one inch
layers for all field work using the same technique exactly.
f. Run an extraction of a sample of the compacted
material to determine asphalt content.
a. Measure the pan and determine precisely the
volume in each inch for the bottom three inches. The
g. Plot the tester reading (in ratio) on the vertical
fourth inch will merely become a catch basin for the light
axis of a calibration sheet similar to that used fur the
material that is compacted into the third inch.
CPN moisture curve, and plot the asphalt content
PERCENTAGE across the bottom.
If a 16" square pan was used, then each inch would
hold precisely 0.1481 cubic feet.
This curve is now an accurate asphalt content curve.
Zero is obtained by compacting a bone dry