Troxler NTO 4730, Manual Of Operation And Instruction

Page: 92 / 158

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 Troxler NTO Asphalt Content Ignition Oven.
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 .