|The furnace test is immediately followed by a hose stream test, which shows how well the wall can hold up in firefighting situations. The gypsum wall, left, disintegrated.|
Recent laboratory tests on gypsum and Autoclaved Aerated Concrete (AAC) walls highlight the dramatic — even life-threatening — difference between a material’s fire ratings and its actual performance in a real fire.
The April tests were conducted at independent Omega Point Laboratories in San Antonio, Texas on two common types of gypsum walls and AAC block, and followed the two-phased protocol of ASTM E-119, “Standard Test Methods for Fire Tests of Building Construction and Materials”. The two phases involved a fire endurance (furnace) test, immediately followed by water application from a hose, which shows how a wall holds up in firefighting situations.
Both gypsum walls disintegrated during the water test. Yet, both walls could still “earn” a 2-hour fire rating under E-119, because manufacturers can take a “second wall” test, which allows a second sample to be subjected to half of the furnace test, plus the water test. In sharp contrast, the AAC walls emerged unscathed.
|The AAC masonry wall, right, emerged unscathed from both tests.|
The inadequacy of the E-119 test method to determine actual performance was raised in the May report on the World Trade Center collapse. As IMI National Director of Market Development/Technical Services David Sovinski noted, “In a real fire, you don’t get to substitute a second wall.”
IMI and the National Concrete Masonry Association have long collaborated to educate designers and builders about ways to improve building safety, and are pressing for timely ASTM action on this vital issue. IMI will continue to press the issue before key code officials and other decision makers.