Improvement of passive fire protection in a gypsum panel by adding inorganic fillers: Experiment and theory

Abstract

Abstract Passive Fire Protection is currently a field of active interest in building technology. One of the different approaches to obtain a material that provides this protection is to add substances to the initial formulation that are capable to absorb heat when the temperature of the material is increased. This is achieved by means of endothermic reactions that these substances undergo at specified temperatures. In the case of a fire scenario huge amounts of heat are released and such heat absorbing reactions delay the achievement of temperatures that can be critical for structural stability. In this work we specifically analyze the behavior of gypsum, which is commonly used in buildings. In order to enrich its endothermic profile we add magnesium hydroxide, calcium hydroxide and calcium carbonate to the sample. These three alkaline earth components have their heat absorbing peaks located along the temperature domain in a way that the temperature rising is reasonably damped. In this work we find, as the main result, that when these three fillers are added to gypsum, the protection offered by the new combination of materials is significantly improved with respect to the behavior of gypsum alone. Under external heating, the component is able to keep itself under critical temperatures for a longer period. For the theoretical description, we first use non isothermal thermogravimetry (TG) to analyze and characterize the kinetic response of each component of the mixture. We propose a conversion function which is based on the correlation between consecutive reactions in neighboring molecules. The heating rate is included in the model as an analytical variable. Later we perform high temperature tests in a tubular furnace and their corresponding numerical simulations where heat transfer is explicitly carried and mass transfer effects are discussed.