Gypsum board reaction kinetics at elevated temperatures

The scope of this work is to provide a framework that can facilitate the detailed simulation of gypsum board thermo-chemistry at ambient and elevated temperature conditions. The paper reviews gypsum board thermo-chemistry, presents a methodological approach for the calculation of composition and reaction energy, and focuses on methods calculating the ‘kinetic triplet’. The chemical kinetics of three main reactions that take place when a gypsum board is exposed at elevated temperatures: evaporation of free moisture content, dehydration of chemically bound water and crystal mesh reorganization were investigated using Differential Scanning Calorimetry measurements under non isothermal conditions and in an inert atmosphere. Experiments using samples of deionized water and commercial gypsum board were carried out at temperatures up to 600 °C, with different heating rates. Mass and energy balance equations were considered in order to define the initial composition of a gypsum board and the energy that is absorbed/produced after the completion of the examined reactions. Model-free and model-fitting approaches were used for the definition of the kinetic parameters of the examined reactions. The approach minimizes the need for expensive and detailed experiments necessary for the determination of the gypsum board behavior at elevated temperatures.

► We study the gypsum board chemical reactivity at elevated temperatures.
► We perform DSC measurements at different heating rates.
► We define the ‘kinetic triplet’ of each of the reactions involved.
► Gypsum dehydration reaction found to be a three step reaction.
► Gypsum crystal structure reorganization reaction is a one step reaction.