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Electrical Resistance Measurements
In order to test the effect of the moisture on the electrical resistance of the
material and the reliability of the measurements, six identical cylinders were
made from each concrete mixture. Three specimens were left to air dry after
demolding and three were placed in water to remain in a saturated condition
for testing. Both the air-dried and saturated specimens were tested at the same
ages for electrical properties. Resistance measurements were taken using a
Leader LCR-475-01 multimeter at one pre-determined location on all six
cylinders for each mixture across its length (Fig. 4-27).
Reactance Measurement and Calculation of Permeability
Reactance of the test cylinder was measured by placing the cylinder in a
copper wire coil and measuring the reactance of the coil with air as the core
(L 1 ) and with the test cylinder as the core (L 2 ). The reactance, L 1 and L 2 , were
determined using a Leader LCR-475-01 multimeter. The resistance
measurements were converted into resistivity values (ohm-cm). The measured
reactance values were then used to calculate the permeability values from the
relationship:
where:
µ
0
µ
1
L
1
= µ 1
=
L
2
L 1 = Reactance of the coil with air core
µ
0
L
L
L 2 = Reactance of the coil with the test cylinder as the core
µ 0 = Permeability of air (4 π × 10 -7 Henry/meter)
µ 1 = Permeability of the cylinder
1
2
We Energies 120
Coal Combustion Products
Utilization Handbook