Thermal Conductivity of Refractory Insulating Concrete

The thermal conductivities and unit weights of seventeen refractory insulating Lumnite cement concretes were determined over the approximate temperature range 500° to 2000°F. The thermal conductivities of all the concretes increased with an increase in temperature, which is usual for amorphous bodies. The aggregates used with Lumnite cement were vermiculite, perlite, pumice, calcined diatomaceous earth, and expanded shale. A graph is given of the thermal conductivities at a mean temperature of 1000°F. for a range of fired unit weights which should be useful in estimating the thermal conductivity of a concrete from its fired unit weight.