Experimental study of the effects of accelerated aging cycles on the fire reaction performance of five wood species

Abstract

The objective of this study is to evaluate the influence of the degradation caused by atmospheric agents’ exposure over time (weathering) on the fire behaviour of five species of wood with different natural durability, according to known durability classes (UNE-EN 350:2016). Two laboratory tests were carried out for assessing the wood of Chestnut (Castanea sativa), European larch (Larix decidua), Black pine (Pinus uncinata), Paulownia (Paulownia tomentosa) and Scots pine (Pinus sylvestris), the later with and without durability impregnation-treatment by autoclave. Laboratory tests involved two processes of accelerated aging cycles (without and with spray) for four weeks following the protocols based on the ASTM G154:2016 and UNE-EN 927-6:2019 standards, in order to make reference to the use classes of exposure to humidity 3.1 and 3.2 defined in the UNE-EN 335:2013 standard. Analysis of the variation of the colour and the appearance of deformations and splitting after accelerated aging were performed. Flammability tests were also carried out to analyse the fire reaction performance of the samples in each stage of the aging test. Differences in colour changes were observed depending on the spraying presence in the aging processes. The results indicated that weathering significantly influences the fire reaction on a wooden surface, especially in softwoods with a medium and low degree of natural durability. Surface roughness and splitting hinder the ability to extinguish the flame. On the other hand, larch proved to have both a good resistance to degradation and good fire behaviour.