Fire behaviour of waterborne intumescent coatings on timber substrate for bushfire exposure

• Main Authors: Baena, J.C., Wang, C., Kabir, I.I., Khalid, A., Nazir, M.T., Yuen, A.C.Y., Ahmad, F., Yeoh, G.H.
• Format: Article
• Published: Elsevier Ltd 2023
• Online Access: http://scholars.utp.edu.my/id/eprint/37340/; https://www.scopus.com/inward/record.uri?eid=2-s2.0-85163725638&doi=10.1016%2fj.firesaf.2023.103836&partnerID=40&md5=4999428d203aa700e020ca6b9271b7ba

The fire behaviour of radiata pine timber, treated with intumescent coatings and exposed to heat flux conditions equivalent to a high-risk bushfire attack level (BAL) is investigated. The experiment is designed for coated timber exposed to bushfire attack levels greater than 19 kW/m2 and up to 29 kW/m2 (BAL-29) in accordance with AS 3959. The timber was coated with a DFT of 400 μm of the developed intumescent formulations based on expandable graphite (EG), ammonium polyphosphate (APP) and a waterborne acrylic resin with high adhesion strength. The coated timbers were tested according to AS3959, for a BAL-29 rating, using a cone calorimeter at 25 kW/m2 for 10 min. Most of the coated samples reported a substantial reduction in the peak heat release rate (p-HRR) and average HRR with values not greater than 100 kW/m2 and 60 kW/m2, respectively. These results satisfy the requirements for bushfire-resistant timber at BAL-29 rating. Formulation 4 (F4), with EG:APP ratio of 3:1 and resin content of 45 wt was identified as the most cost-effective formulation. Coatings with high loading of EG and APP provided the best fire protection to the timber substrate, however, a larger char with a less compact structure is formed. © 2023 Elsevier Ltd