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Harbor
Grout Resistivity Measurements
A grout-sample-filled soil box (ASTM G57-95a) was employed to determine
grout resistivity. The Sikatop 123 Plus? was monitored periodically
after placement in the box using 4-probe AC-impedance. From an initial
value of 1,200 ohm-cm at 12 hours, the resistivity increased to
over 30,000 ohm-cm after 5 days. The subcontractor’s prior
validation of this material to meet the specified resistivity of
less than 25,000 ohm-cm is suspect. The resistance of the Sikatop
123 Plus? grout increased steadily for months after the installation
(Figure 37). Consequently, the voltage used to drive the ICCP system
has risen steadily to maintain the required current. The resistivity
rate of increase should diminish with the passage of more time.
However, two ICCP sections already require more than 10 volts to
provide 20 mA.
Figure 37. Resistivity of Sikadur 123 Plus© with time.
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