Users Manual

PDP User’s Guide Appendix H:Glossary
H-1
Glossary
Below is an explanation of terminology used in PDP. For a full glossary of GPR-
specific terms, please visit: https://www.sensoft.ca/glossary-of-gpr-terms/
Air Void Content – expressed as a percentage of how much of the volume in the
asphalt is air.
AASHTO – short for American Association of State Highway and Transportation
Officials. This group sets technical standards for design and construction of
roads, bridges and associated materials.
Compaction – refers to the process of running a steamroller over newly poured
asphalt to remove air and ensure uniformity and smoothness of the asphalt
road. Compaction is also a measured quantity and is often used in place of
normalized density. Both mean the same thing.
Density – refers to the absolute density of the asphalt, expressed in units of
g/cm
3
.
Density Offset – this value is used when calculating Density by applying a shift
in the data. A user would input a density offset value to bring the PDP surveyed
measurements in line with that from a core sample or possibly calibrated nuclear
gauge measurement.
Density – Site Specific –measurements of the asphalt properties at a site are
used to create a unique site-specific means of calculating density. While more
complex than just density, this can be a more accurate representation of the
true density of the asphalt.
Filter Length – the filter applies a horizontal smoothing filter to the data to
reduce noise “jumps” in dielectric permittivity that are observed. The filter trace
length options are an indication of how aggressive the filter is; the larger the
number of traces, the more smoothed the data will be as erratic “jumps” will be
filtered out.
Free Run - data is acquired based on a time interval. A data sample (or trace) is
collected every x seconds, which can be specified.
GPR – short for Ground Penetrating Radar, this is a geophysical method of using
low-power radio waves to explore the subsurface. PDP is based on GPR
technology.
Histogram – a graphical display showing the shape and spread of values for
continuously measured data