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Thermal Resistivity of Concrete

Thermal Resistivity of Concrete

Thermal Resistivity of Concrete

(OP)
I have been asked by an electrical enginner in our firm to provide a value of the thermal resistivity of concrete. I have been unable to locate a reference that discuuses this topic. According to the EE "the lower the thermal resistivity (higher thermal conductivity) the better we are electrically speaking". Can anyone provide insight into this property?

RE: Thermal Resistivity of Concrete

The thermal resistivity (R-value)will depend on the density of the concrete AND the chemical composition of the aggregates. Generally, lighter concrete has greater resistivity (insulation) than heavier concrete.

I don't have a specific reference handy, but normal weight concrete is in the range of 0.06 to 0.11 hr*sf*degree F/BTU/in (mKW) if I recall correctly. Lightweight concrete, which is less than 115 pcf would have a range of 0.11 to 0.19.

This is usually based on a guarded hor plate test with measurements under steady state conditions - my mind in failing on these details.

You should be able to find it in the ASHRAE manual.

I still do not know how this relates to electrical, but the amount of range in values should pose a problem unless someon wants to pay for and schedule an actual test.

Dick

RE: Thermal Resistivity of Concrete

We have run into this quite a bit. The new 345 kV lines generate a considerable amount of heat and if it is not disapted properly, can cause the line to fail. Geotherm in Canada (and I believe in Arizona) provides testing and expertise in this field. Will have contact info next week.
They are definetely the guys to ask.

RE: Thermal Resistivity of Concrete

The High density concretes were used in nuclear construction.
Made with limonite, magnatite and steal punchings as aggregates. A Complex and expensive proceedure

Intrusion Prepakt /marineconcrete.com

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