Protection of pre-treated wood and construction materials using intumescent coatings

Intumescent paints’ behaviour is investigated for protecting wood pre-treated with phosphate or a silicate-based flame retardant. Additionally, the ageing effects of intumescent paint under several conditions are investigated. The cone calorimeter is applied, measuring the reaction to heat responses and the char development. Pre-treatment showed an improved fire performance of samples with intumescent coatings. The effects depend on the moisture contents and the homogeneity of the pre-treatments. Also, the experiments showed differences in fire resistance depending on the ageing method. UV exposure ageing retained the heat-insulating properties, while samples immersed in acid suffered a drastic reduction of their fire resistance. The latter ageing test increased the char’s pore size resulting in a reduced expansion factor and reduced thermal insulation performance of the intumescent coating.