Abstract
This study aims to establish the rational prediction of the fire protection performance of insulated wooden walls to reduce the full-scale fire tests. Series of small-scale furnace tests are conducted on various types of wall constructions with rock-wool insulation, the most stable practical insulation material.
The results of the fire tests and one-dimensional steady-state heat transfer calculation lead the following conclusion on the wooden insulated walls with rock-wool insulation.
Without cavity, the calculation can almost reproduce the temperature profile in the wall as the disadvantageous situation that temperature becomes higher in. And the engineering problems, to grasp the heat balance in cavity and to build calculation model of it, are left.
Fire protection performance is required flame insulation property, heat insulation property and non-damage ability in Japan's building standard act.
Heat insulation property can be predicted by checking thermal resistance. If insulated walls have thermal resistance bigger than 1.70m2K/W when heated for 45 minutes, or 2.10m2K/W when heated for 60 minutes, heat insulation property can be secured enough.
Heat insulation property is made a difference between when heated from indoor side and from outdoor side by cavity or the material which phase conversion happens in high temperature. In non-insulated wall, infilled insulated wall and additional insulated wall, heat insulation property become more disadvantageous when heated from indoor side than from outdoor side, with gypsum board as interior material. In addition, cavity acts on more advantageous against heat insulation property.
The time when combustion begins in the pillars depend on thermal resistance of external protection layer when heated from outdoor side, and depend on how long gypsum board delays temperature rise at around 100 degrees Celsius when heated from indoor side. Non-damage ability becomes more disadvantageous when heated from indoor side than from outdoor side in non-insulated wall and all insulated wall with rock-wool even if any constructing method.
The infilled insulation raises the back-surface temperature of the protection layer, also reduces the damage by protecting the side of the pillar. And the external insulation disturbs heat diffusion to the back side when heated from indoor side, also reduces the damage by protecting the front of the pillar when heated from outdoor side. Thus the infilled insulation and the external insulation have both advantageous factor and disadvantageous factor for non-damage ability. The combination of these factors can explain about non-damage ability in every constructing method of the insulated wall.
In addition, It is clarified that non-damage ability can be predicted by checking the back-surface temperature of the protection layer. This point suggests potential predictability by calculation, because the one-dimensional steady-state heat transfer calculation can almost reproduce the temperature profile, without cavity.
