Evaluating the use of minerals as forest fire retardants

The fire retardancy of carbonate minerals hydromagnesite, huntite and natural mixtures of hydromagnesite and huntite, on forest species was tested by analytical (differential thermogravimetry under air atmosphere) and laboratory-scale (flame spread test) methods. The selected forest species (Pinus halepensis Mill. and Cistus incanus L.) were collected from a wildland/urban interface zone near Athens and were treated with 5%, 10%, 15% and 20% w/w of the minerals. On the basis of differential thermogravimetric analysis, minerals decrease forest species combustibility (by increasing maximum weight loss rate and combustion duration) and consumability (by increasing combustion mass residue) and increase their sustainability (by increasing combustion duration). Additionally, the flame spread tests indicate that the minerals decrease forest species ignitability (increase time for ignition) and combustibility (decrease flame spread rate, maximum flame height and mean flame intensity), and affect their sustainability (by increasing the flame duration) and consumability (by increasing the mass residue). Among minerals examined, the most efficient retardant was the mixture of huntite and hydromagnesite.