A Comparative Study of Ignitibility and Combustibility Properties of Four Algerian Plants: Application to Wildland Fuels Classification

To seek a fire-resistant fuel, the reaction to fire of Algerian Phoenix dactylifera leaves known for their thermal resistance was compared to that of three highly flammable Algerian fuel particles: Eucalyptus globulus leaves and Pinus halepensis and Pinus canariensis needles. By using a small-scale cone calorimeter, their thermal properties were investigated under a low irradiance of $3.5\mathrm{kW}/m^2$, while their ignition and combustion properties were examined with irradiances of $17.5$ and $50\mathrm{kW}/m^2$. Eucalyptus globulus leaves were found the most ignitable fuels with the largest released heat, while Phoenix dactylifera leaves were found by far the least ignitable fuels with the smallest released heat, particularly under large heat flux intensities. Based on a theoretical analysis of thermal and ignition properties, a new flammability/spreading index combining the ignitability and combustibility metrics was proposed to rank these fuels. This index was compared with the fire retardancy index used for polymer composites and adapted to these plants because it uses a cone calorimeter. A similar ranking order was obtained between the two indices for the considered fuels, where Eucalyptus globulus leaves were found by far the most fire-spreading fuels particularly at large fire intensity. On the other hand, Phoenix dactylifera leaves appeared by far the least fire-spreading fuels particularly at large fire intensity. The possible use of Phoenix dactylifera trees as extreme fire retardants in wildland fuel management, as well as their use at the wildland–urban Interface, are discussed, but these results should be confirmed at a large scale.