This study is part of an ongoing project on modeling vegetation fires and their impacts on dwellings at wildland-urban interfaces. As a first step, fire tests were conducted at laboratory scale on both wooden wool litter and rockrose non-natural hedge. To this end, a 0.5 m x 0.5 m x 1 m hedge reconstituted from rockrose branches was burned under a Large Scale Heat Release (LSHR) apparatus. A litter of wooden wool was used before and under the hedge to mimic an ignition from an underneath burning herbaceous layer. These fire tests provided experimental data for mass loss and heat release rate, which were used as a basis for comparison with the simulations performed by using the Wildland-urban interface Fire Dynamics Simulator (WFDS). To numerically model the rockrose hedge, the distribution of the different particle classes (leaves, twigs of various diameters) was determined as well as their physicochemical properties. The comparison of the experimental data and predicted quantities showed a good agreement, whether for wooden wool burnings alone or mixed wooden wool and rockrose hedge.

Smoke is an important component of wildfires. Specifying the combustion process of different materials allows scientists to better prevent and adopt public health measures. This experimental study contributes to a better characterisation of the smoke emitted by two types of decking, wood and thermoplastic, commonly used in terraces. Emission factors were characterised using a cone calorimeter for different incident fluxes ranging from 10 to 50 kW/m². The study showed that compared to wooden (pine) decking, thermoplastic (polypropylene) decking produces more gases and aerosols, less VOCs, but with a chemical composition that is more carcinogenic.

The recycling of waste materials is a way of limiting over-consumption and optimizing the value of resources. Within the framework of a circular economy, this can be applied to post-consumer plastic wastes, but also to biobased by-products. Hence, this work deals with the design of composite materials by combining recycled high-density polyethylene (HDPE) and polypropylene (PP) coming from bottle caps and virgin cork of insufficient quality for cork stoppers. Different fractions (0, 5, 10, 15, and 20 wt%) of virgin cork were incorporated into recycled polymers (HDPE_r and PP_r). These composites were prepared without a coupling agent or fire retardant. The morphology and mechanical properties of the different conditionings were studied and compared. The thermal decomposition and the fire behavior of the composites were also investigated. Microscopy revealed the poor adhesion between the cork particles and polymer matrices. However, this limited interaction affected only the tensile strength of the PP_r composites, while that of the HDPE_r composites remained almost constant. The addition of cork was shown to reduce the time to ignition, but also to promote charring and reduce the heat released during the composite’s combustion. The feasibility of composites based on cork and HDPE_r/PP_r waste opens the way for their reuse.

During a wildfire, combustible exterior building materials, like decking assemblies, may be ignited and cause severe damage or total loss of a dwelling

Research applications of three-dimensional, time-dependent, computational fluid dynamics fire behavior models, such as the Wildland Urban Interface Fire Dynamics Simulator (WFDS)

With global warming and rising occurrence of drought conditions, the risk of fire spreading at Wildland–Urban Interfaces (WUI) increases every year