CALIBRATION OFFSET
Troxler calibrates the Model 3450 RoadReader Plus at the factory
for use on soils, asphalt, and concrete. The operating range of the
gauge is 1100 to 2700 kg/m
3
(70 to 170 pcf). If the gauge is to be
used on materials outside of this range, the operator can adjust the
gauge using an offset. The 3450 gauge provides three offsets: wet
density, moisture, and trench.
Perform a wet density offset if the test material is outside the range
of material composition and/or texture used during factory
calibration.
Perform a moisture offset if the test material contains hydrogen in
forms other than water, or is high in neutron absorbers. Examples of
materials rich in hydrogen are cement, gypsum, coal, or lime. The
moisture offset for soils containing these materials is a negative
value. If the material is high in neutron-absorbing material, such as
boron, cadmium, or chlorine, then the offset must be a positive
value.
Perform a trench offset before taking measurements inside a trench
or close vertical structures. Vertical structures scatter neutrons and
gamma photons back to the gauge. This scattering could result in
inaccurate moisture and density readings.
NOTE
When turned off, the gauge disables all special
calibrations and offsets.
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