I need to measure the electrical resistivity of a concrete sample following the procedure described in ASTM C-1760.
The procedure requires a 60V DC potential to be applied across the concrete sample (cylinder with 10cm diameter and 10cm length) and the current measured to obtain the bulk resistivity of the sample.
The problem is that I don't have a power supply capable of delivering 60V.
I was wondering if a regular multimeter can produce the same result using the ohm function. The expected sample resistivity should range 50 – 500 Ohm.m
Best Answer
The Ohm function on your multimeter will use the voltage-current relation to determine the resistance of a sample. It will either apply a voltage and measure the current delivered, or force a current and measure the voltage required to deliver it.
But it will almost certainly not use a voltage as high as 60 V, so it won't meet the needs of your test.
Probably the ASTM spec requires a 60 V source to provide a repeatable test method that allows for breakdown of some of the thin layers of oxide material within the concrete, but not others. The higher voltage used may also be needed to accurately measure currents due to ionic transport within the never completely cured concrete.
Therefore I'd expect you need to use an actual 60 V source to achieve a compliant measurement.