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.

The use of physics-based models to simulate vegetation fires has been steadily increasing over the last decade. These models offer the possibility to study quickly and at a low cost the combustion of vegetation according to a wide set of parameters which are difficult to control experimentally. However, the validation and improvement of these models is still ongoing and coupled experimental / numerical approaches are needed. In a previous work, a validation of the numerical code WFDS was done for the spreading of fires across pine needles fuel beds. It highlighted the ability of WFDS to reproduce the combustion dynamics and the related physical quantities (heat release rate, mass loss rate, rate of spread) during the growing and steady-state phases of the fire. The objective of the present work is to test WFDS for the prediction of the combustion of a natural shrub, which is a more complex fuel than a fuel bed. As a first step, 3 shrubs of rockroses (Cistus monspeliensis) were characterized. The distribution of the different classes of particles that compose the shrubs was determined and used as input for the shrub model. A series of 41 fire tests were conducted on the shrubs to investigate their flammability. Ignition was performed using radiant panel. The measurements of the main physical quantities were also used as a comparison basis for the numerical approach. A numerical model of shrub was developed from the characterization results. Then, the combustion of the shrub was simulated with WFDS. The grid mesh resolution needed for the simulation was estimated from the extinction length within the shrub crown and from the heat release rate (HRR) during the fire tests. Finally, experimental measurements and predictions were compared to determine the capability of WFDS to reproduce the combustion of the shrubs. The experimental investigation of the shrub flammability showed four different regimes of combustion governed mainly by the location of ignition. Simulations were run for the flammability regime that exhibits the best reproducibility. The comparison between simulation and experimental results demonstrated a good ability of WFDS to assess the most relevant fire properties, namely the peak of HRR, flame duration and consumption rate. The main differences between the predictions and observations were identified during the ignition and extinction phases. A plateau of HRR is predicted shortly after the ignition, limiting the fire growth. In addition, the duration of the predicted smoldering phase is too short which causes a total extinction of the fire few seconds after the end of the flaming phase.

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

Among the vectors of fire propagation towards buildings in the WUI, ornamental hedges have been identified as one of the main elements