Bench Tests for Characterizing the Thermophysical Properties of Type X Special Fire Resistant Gypsum Board Exposed to Fire

Abstract

ASTM C1396 Standard Specification for Gypsum Board defines type X special fire resistant gypsum board on the basis of the fire resistance of a load bearing wood framed gypsum partition tested in accordance with ASTM E119 Standard Test Methods for Fire Tests of Building Construction and Materials. Monitoring individual product performance in a wall system fire test presents serious challenges to the manufacturing facility. The expense and complexity of operating an ASTM E119 wall furnace makes it impossible for plants to run the defining test on site. In addition, many factors influence the outcome of a fire resistance test making it difficult to assess the performance of the gypsum board independently of other wall system and laboratory influences. In 2003 the Gypsum Association formed an ad hoc Product Standard Task Group in an attempt to develop an improved definition of type X gypsum board. The new definition had to be equivalent to the current ASTM C1396 specification but based on bench scale tests of the high temperature thermophysical properties of type X gypsum board alone. The tests must also be suitable for use as in-plant quality assurance procedures. A suite of three tests resulted. Their development and correlation to the ASTM E119 test has been documented by the authors in an earlier paper. An analysis of the precision of these three test methods is presented here.