Impact of Fire Exposure on Heat Transmission in Concrete Slabs

Abstract

The ASTM Standard E-119 specifies that when a structural component is fire-tested by exposing one surface to a standard fire exposure, the component fails if the temperature of the unexposed surface of the test component rises 250°F (130°C) or more during the rating period. The standard fire exposure usually is not representative of the compartment temperatures that develop during an actual fire, and the test results may not be indicative of how components might actually behave. In particular, the standard test may give an overly pessimistic appraisal of the behavior of concrete components greater than 76 mm (3 in.) thick and that have excellent insulating characteristics. Design economies might be achieved by allowing the use of natural fire exposures rather than one universal test in assigning fire ratings and in fire-resistant structural design.