Which of the following is NOT a physical property standard that the test specimen shall be tested for?

The physical property standard that is typically not included for testing in refractories, as per established guidelines, is thermal conductivity. In the context of refractory materials, testing often focuses on properties that directly relate to the performance and durability of the material when exposed to high temperatures and various operational environments.

Density, permanent linear change, and cold crushing strength are critical metrics for evaluating refractory performance. Density is essential as it influences thermal stability and overall strength. Permanent linear change assesses dimensional stability under heat exposure, which is key for ensuring that the material maintains its structural integrity. Cold crushing strength measures the material’s strength at room temperature, providing insight into its mechanical capabilities before it is put into service.

Thermal conductivity, while important in certain contexts, is not always a primary standard for refractories because the operational conditions and temperature ranges may not make this property as critical for the intended applications of the materials tested. Thus, the emphasis is typically on the other properties, which have a more direct correlation to the performance and longevity of refractory linings in their working environments.