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Introduction

Fire resistive materials (FRMs) have been utilized for many years [1] to protect steel (and other) substrates during a fire exposure, by limiting or reducing the temperature rise experienced by the steel. While it is obvious that the thermophysical properties, mainly thermal conductivity, heat capacity, density, and heats of reactions and phase changes, of the FRMs will control their performance in this application [2], few standard test methods are readily available for actually measuring these properties over the wide temperature range of relevance during an actual fire exposure (from room temperature to greater than 1000 ºC, for instance).  Most evaluations of these materials are currently performed on a pass/fail basis using the American Society for Testing and Materials (ASTM) Standard Test Methods for Fire Tests of Building Construction and Materials (E 119) [3], which provide a time-based performance rating (e.g., 1 h, 2 h, or 3 h, etc.).  While these ratings are used daily by architects and designers for selecting passive fire protection strategies, they provide little direct information of value for engineers and scientists who are interested in simulating the fire/structural performance of buildings and other structures. While some twenty years ago, Wickstrom [4] first detailed how the thermal resistance of FRMs could be obtained from fire tests where furnace and steel temperatures were recorded, such computations are still rarely employed in the United States. The objective of this paper is to present a methodology for estimating the room temperature heat capacity and temperature variable thermal conductivity of FRMs by combining two existing experimental techniques, namely the transient plane source method [5; 6] and a recently developed slug calorimeter technique [7]. In addition to providing estimates of these critical thermal properties, the presented protocol also provides supplemental information on the effects of chemical reactions, phase changes, and mass transport of reaction gases on the thermal performance of the FRMs being evaluated.