Thermal conductivity k-values can be determined from room temperature to 1500 ◦ C, or the maximum service limit of the refractory, or to the temperature at which the refractory is no longer dielectric. The values stated in SI units are to be regarded as standard. The data were taken from the data logger and thermal conductivity was calculated using the software from the แรมด้า-instrument. Thermal conductivity was calculated using the following equation.