• gypsum;
  • thermal conductivity;
  • fire;
  • porous structure;
  • anhydrite II;
  • anhydrite III


The thermal conductivity of gypsum plasterboard at temperatures beyond its dehydration/calcination temperature is, besides the effective heat capacity, the main parameter defining the increase in heat transfer when the board is submitted on one side to a strongly transient temperature boundary condition. The present study investigates the significant rise in thermal conductivity of dehydrated gypsum plaster board between 200 and 800 °C, reaching the initial hydrated value of 0.3 W/(m·K). It is shown that the main reason for this increase is independent of radiative and convective heat transfers and only due to an enhancement of the conduction between the single crystals induced by an effect similar to sintering. Copyright © 2014 John Wiley & Sons, Ltd.