3.6.3 Calibration Comparison
A. Arrange to have physical core samples taken from the center of each marked
circle location in the 10 foot strip.
B. Enter the density value from each core sample on the data table.
C. Calculate the numeric difference between the average PQI readings and the
core density lab reports. Add or subtract to obtain a small number which
represents the difference between the density value that the PQI is reading
versus the actual density values from the core samples. These numbers are
used to adjust the calibration offset value stored in the PQI so that the unit
can indicate readings that are very close to the actual density values for the
asphalt mix at the job site.
From the Calibration Menu, press ‘1’ to access the normal calibration function,
which will display the following screen:
Offset [D] = 0.0
1) PQI reads to hi
2) PQI reads to lo
ENT) Exit
The function is used when you have obtained a number of PQI readings,
obtained a number of core readings, and calculated the average amount that the
PQI is reading too high or low. The first step is to press a key to indicate whether
the PQI is reading too high or low. After pressing the key, the following screen
will appear:
Offset Adjustment
Adjustment:
At this point you should enter the difference in the PQI and core readings.
For example, if the average core reading was 142.3 lb/ft3 and the average PQI
reading at those locations was 143.1 lb/ft3, then the PQI is reading 0.8 lb/ft3 too
high, relative to the cores and you would enter “0.8” or “.8” at the “Adjustment”
prompt.
Note that the calibration should be entered in the current density units. If
the PQI is set to kg/m
3
, the adjustment should be entered in to kg/m
3
.
15
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Summary of Contents for PQI 301
Page 1: ...Pavement Quality Indicator Model 301 Operators Handbook ...
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