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Wildland-urban interface (WUI) fires are wildfires that originate in proximity to and ultimately spread into residential homes, neighborhoods, and communities and cause extensive property damage and potential loss of life. To help understand and mitigate the impact of WUI fires, accurate pyrolysis models can assist the simulation of fire growth and spread. These tools, which simulate the thermal decomposition of materials, enable a better understanding of fire behavior, and can help improve the fire resilience of building materials and structures and can ultimately contribute to safer communities.

In their article "Pyrolysis Models for Pressure Treated Wood and Wood-Plastic composite," published in the journal Fire and Materials, Ä¢¹½tv's thermal scientist Jacques De Beer, Ph.D., and co-authors have developed pyrolysis models that define the thermal decomposition and ignition properties of pressure-treated wood (PTW) and wood-plastic composites (WPC) — common deck and auxiliary structure materials frequently used as construction materials in the WUI. Dr. De Beer developed a bench-scale test rig and analyzed testing data from several experiments to draw intriguing conclusions about these materials.

Characterizing how decking catches fire

Leveraging advanced techniques, including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), microscale combustion calorimetry (MCC), and the Controlled Atmosphere Pyrolysis Apparatus (CAPA II), the authors characterized the kinetics and thermodynamics of thermal decomposition and combustion. PTW and WPC cone calorimetry testing was also utilized to validate the accuracy of their pyrolysis models using a computational framework, ThermaKin 2Ds.

Using these methods, the team successfully characterized the decomposition rates and ignition thresholds for both materials. As part of an effort to predict how materials contribute to WUI fires, pyrolysis modeling can be useful for construction stakeholders, local governments, responding fire departments, and consumers in ongoing efforts to improve construction fire safety, including efforts to reduce the ignition of construction materials in the WUI and subsequent fire spread among structures during a WUI fire.

From the publication: "The samples were mounted under the cone heater by wrapping the bottom and sides with aluminum foil and setting them atop two sheets of 1.3 cm thick Kaowool PM insulation board. … Ignition was accomplished via a spark igniter located 13 mm above the top sample surface. Three tests were performed on each material at 50 kW m^−2 of set radiant heat flux to accumulate statistics."