A change in the length of a specimen measured before and after heating to a...

Permanent linear change (PLC)measures the irreversible dimensional change of a refractory specimen after it is subjected to a high temperature for a specified duration. It is expressed as a percentage of the original length. This property helps evaluate the stability and thermal compatibility of refractory materials during service.

This is distinct from:

Modulus of rupture (A): a strength test under bending.

Modulus of elasticity (C): a measure of stiffness.

Pyrometric cone equivalent (D): a test for melting behavior.