The performance of fire retardant treated wood in outdoor conditions

It is very important to take fire safety and prevention measures in order to ensure safety in the usage of wood against fire. One of the most important precautions is to impregnation of wood with fire retardants. However, there is a limitation of using fire retardant for wood in outdoor environment because of the low leach resistance of the inorganic fire retardants. In this study, black pine (Pinus nigra ssp. pallasiana) wood was impregnated with 10%, 20% and 30% aqueous solution of fire retardants (di-ammonium phosphate, borax and boric acid) along with the Maillard reaction agent (glucose) mixture. Then, heat treatment was applied on the wood samples at 120, 150 and 180 °C for 1 hour. Both Impregnated and heat treated black pine wood specimens was evaluated for the pH value, crystallinity ratio, leaching rate, density, water absorption, volumetric swelling, mechanical properties, color changes and thermal properties. The statistical analyses indicated that the temperature of heat treatment at 180 °C had better performance of leach resistance, thermal properties, water absorption and volumetric swelling. Conversely, pH value and mechanical properties as bending strength of the impregnated wood that was heat treated at this temperature exhibited the lower performance. Therefore, it is recommended that the corrosion-resistant fasteners can be used as having the acidic pH value which affects fastener performance in the wooden joints. It is concluded that heat treatment is applicable for fire retardant treated black pine wood to be used in the external environment.