Abstract
Bushfires are increasingly common globally and have major effects on infrastructure, including electrical networks. In Australia, chromated copper arsenate (CCA)-treated poles are commonly used to support these networks. While effective against fungal and insect attacks, CCA is prone to smouldering combustion after fire events, leading to post-fire failure. Identifying additives to mitigate this characteristic would improve performance, reducing the need to replace poles affected by minor bushfire events. This study is part of a larger project to develop additives to inhibit smouldering in CCA-treated wood. Potential smouldering inhibitors, including diammonium phosphate (DAP) with two different water repellents, silicone oil (SO) and paraffin (PA), and chlorinated paraffin wax (CPW), were evaluated using thermogravimetric analysis (TGA). The TGA parameters examined were the char oxidation temperature, the difference between the pyrolysis and oxidation temperatures, and the mass residue. DAP markedly reduced smouldering compared to CPW, with the 5.5 wt% DAP treatment achieving the highest effectiveness. Furthermore, SO proved more effective as a water-repellent agent than PA. These findings highlight the potential for combining DAP with SO to enhance the fire resistance of CCA-treated timber poles, offering long-lasting protection to mitigate smouldering risks in bushfire-prone regions.