Fire behaviour of gypsum-bonded particleboards

The fire behaviour of gypsum-bonded laboratory particleboards with varying wood contents ranging from 15 to 40% was investigated. Chips from poplar, pine and alder and from old particleboards were used to manufacture the test boards. In some test variants chips were used that had been treated with fire retardants. Board density ranged from 950 kg/m(3) to 1300 kg/m(3) Fire behaviour was assessed by means of the furnace test according to DIN 4102, the determination of calorific potential and smoke density measurements. The results presented in this paper show that the fire behaviour of gypsum-bonded particleboards can be influenced to a large extent by the wood/gypsum ratio as well as by density. The investigations proved that with a wood content below 25% gypsum bonded particleboards may reach the classification ''structural material class A2'' of DIN 4102. Up to a wood content of 35% the maximum temperature increase in the furnace test remained below the standard requirement of 50 K. Flame height and fire duration were within the standard boundary values only up to a wood content of 25%. The use of fire retardants for wood chips led mainly to a retardation in flame development and hence to a distinctly curtailed fire duration. Concerning smoke density measurements good correlation existed between smoke development and wood content. Independent of the method selected to test the boards values were found to lie considerably below the required boundary values, especially for wood contents in the range of 15 to 25%.