6-2
CORRECTING %AC MEASUREMENTS
WARNING
To prevent personal injury or equipment damage, the
operator should become familiar with the safety
warnings and information in Chapter 2 before
operating the ICO.
During the ignition process, a complex interaction of various
effects (mass, temperature, airflow, materials type) can produce
a result that could be interpreted as a “mass loss.” This “mass
loss” effect could consequently affect the determination of the
asphalt content.
To compensate for this “mass loss” effect, the oven uses an
aggregate correction factor (ACF) to adjust asphalt content
measurements.
The magnitude of the “mass loss” effect is influenced most by
the type of aggregate. Granite aggregates have been shown to
yield the least “mass loss,” while limestone aggregates can
produce higher losses. To ensure accurate determination of the
asphalt content, an aggregate correction factor (ACF) is
necessary to compensate for this aggregate “mass loss” effect.
The following sections provide instructions for determining an
ACF.
To ensure precise asphalt content measurements, use a
consistent sample preparation and selection method. For more
information, refer also to ASTM standard D 75 (AASHTO T2),
Standard Practice for Sampling Aggregates.
EQUIPMENT NEEDED
The following equipment is required to determine an ACF to
adjust the %AC measurements:
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