Study on prediction method for the insulation of gypsum board using inclusive thermal conductivity in fire resistance tests

Abstract In this study, a method for predicting the unexposed surface temperature of a wall is proposed based on the concept of “inclusive thermal conductivity,” which considers the heat and mass transfer of materials containing moisture. The inclusive thermal conductivity is estimated based on the results of temperature measurements obtained from actual fire resistance tests. The proposed method enables the estimation of material thermal conductivities that are difficult to assess using conventional methods. The inclusive thermal conductivity is affected by the deterioration and evaporation that occurs in the materials, which are estimated from the fire resistance test results. The unexposed surface temperature predictions for the gypsum boards of different thicknesses are numerically analyzed by changing the number of inclusive thermal conductivities. The inclusive thermal conductivity of the gypsum board increases as the temperature increases. The unexposed surface temperature prediction is affected by the exposed surface temperature of the fire resistance tests, and the prediction accuracy increases as the difference in the material thickness decreases. The exposed surface temperature obtained from the fire resistance test results influences the prediction of the unexposed surface temperature. The prediction accuracy of the numerical analysis using the inclusive thermal conductivity is confirmed to be practically sufficient.