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The thermal behavior of a commercially widespread gypsum board (810 kg/m 3) under fire condition has been investigated. For this purpose two 12 mm thick gypsum boards are subjected to the standard fire ISO 834 and the temperature distribution within them is measured by means of thermocouples placed at different depths in the samples. The results hereof are used to validate a numerical model based on the density, thermal conductivity, and effective heat capacity of the gypsum board as functions of temperature. The effects of dehydration/calcination and decomposition on these properties are determined by using thermogravimetric analysis, conductivity measurements after different heat treatments, and differential scanning calorimetry under air flow, respectively.

The charring rates of 12 different wood species originating from Europe and the tropics with densities ranging from 350 to 750 kg/m 3 were investigated to obtain clues on their fire resistance behavior. This was done by measuring the thickness of the charred layer after a 30-min exposure to the standard fire ISO 834-1. No correlation was observed between charring rate and density. In search of another physical property that could be used as an indicator of fire resistance, the oxygen permeabilities of the selected wood types were measured. A strong correlation between oxygen permeability perpendicular to the wood fiber direction and charring rate was found, which is quite straightforward given that oxygen is the necessary component to enable smoldering and ignition, both affecting the charring rate. It seems that oxygen permeability is potentially more suitable as a parameter to evaluate the fire resistance of char-sensitive wooden constructions, rather than density. No general preference of the tree ring orientation from 0° (tangential) to 45° and 90° (radial) was found for these measurements.

Four different commercially available gypsum plaster boards are investigated experimentally at fire temperatures with respect to their thermophysical properties i.e., thermal conductivity, effective heat capacity and density. It is shown that depending on different ingredients (carbonates) different endothermic reactions occur between room temperature and 900°C. These reactions strongly influence the temperature dependence of the mentioned properties which in turn affect the response of the material to fire. Based on these experimental results the thermal reaction of a gypsum-protected steel column in fire is modeled for the four types of gypsum. The results of numerical simulations demonstrate clearly the advantages caused by certain ingredients of the chemical composition of gypsum plaster boards.