Testing of representative elements of the wall construction in accordance with standard fire test methods is usually measured by ASTM E 119, Standard Test Methods for Fire Tests of Building Construction and Materials.
Calculation methods determine fire resistance ratings based on physical and material properties of the concrete masonry unit, such as the equivalent thickness and aggregate types used in the manufacture of the concrete masonry units.
These calculation methods are based on extensive research with has established a relationship between physical properties of materials and the fire resistance rating. The rating is a function of the aggregate used in the manufacturing o the units and the equivalent thickness of the unit.
Private listing services allow a designer to specify a fire rated assembly which has been previously classified. The listing service monitors materials and production to verify that the concrete masonry units are in compliance with appropriate standards.