Combination of Transient Plane Source and Slug Calorimeter Measurements to Estimate the Thermal Properties of Fire Resistive Materials*

The thermal properties of fire resistive materials FRMs as a function of temperature critically influence their ability to protect a steel structure during a fire exposure. Measurement of these properties is complicated by the microstructural heterogeneity of typical FRMs, the need to measure properties over a wide temperature range from room temperature to 1000°C and higher, and the reactions, phase changes, and volumetric changes that the materials may undergo during exposure to elevated temperatures. This paper presents an integrated approach for determining thermal properties via a combination of two experimental techniques, namely the transient plane source and the slug calorimeter methods. The former is utilized to provide an estimate of the volumetric heat capacity and a room temperature thermal conductivity value for the FRM under study, while the latter is employed to estimate the variation in effective thermal conductivity with temperature, including the influences of reactions and mass transport during multiple heating/cooling cycles. The combination of the two techniques is demonstrated for four different inorganic-based FRMs. Their extension to organic intumescent systems is also discussed.