Effects of phosphoric acid and diammonium phosphate treatments on the physical and fire-retardant properties of five selected Nigerian wood species
IRG/WP 24-20713
J Owoyemi, T O Akinwamide, O M Ibrahim, E A Iyiola
Wooden products in buildings are major sources of fuel for fire outbreaks. Effects of phosphoric acid and diammonium phosphate treatments on the physical and fire-retardant properties of wood species commonly used in buildings were evaluated. The timber species utilized in this study were sourced from the sawmill sector located in Akure, Nigeria, encompassing Brachystegia laurentii, Khaya ivorensis, Pterygota macrocarpa, Celtis zenkeri, and Terminalia superba. Specimen preparation and subsequent testing procedures adhered to the guidelines outlined by the American Society for Testing Materials (2009) to assess the physical properties. The wood samples recorded moisture content values of 42.98%, 34.11%, 29.84%, 29.45%, and 22.49% and density values of 536.36 kg/m3, 461.79 kg/m3, 695.76 kg/m3, 807.04 kg/m3, and 737.43 kg/m3 for Pterygota macrocarpa, Terminalia superba, Brachystegia laurentii, Khaya ivorensis, and Celtis zenkeri. The experimental findings regarding the impact of treatments on the physical properties of wood samples revealed that specimens obtained from T. superba, P. macrocarpa, C. zenkeri, B. laurenti, and K. ivorensis wood and treated with phosphoric acid, diammonium solution, and untreated conditions exhibited volumetric swelling percentages as follows: 6.46%, 8.99%, and 5.10%; 7.33%, 9.50%, and 9.32%; 7.25%, 6.85%, and 13.16%; 7.04%, 6.75%, and 7.39%; and 5.53%, 8.15%, and 8.59%, respectively. The analysis of variance showed that this treatment varies significantly among the wood species and varying treatment. Further, the rate of combustion showed that T. superba, P. macrocarpa, C. zenkeri, B. laurenti, and K. ivorensis recorded percentage weight loss of 8.43%, 17.47%, and 36.90%, 6.40%, 17.64% and 37.05%, 7.20%, 14.68% and 27.43%, 7.22%, 13.72% and 19.85%, and 5.63%, 9.23% and 14.87% for samples treated with phosphoric acid, diammonium solution and control respectively. The fire-retardant treatments had a significant effect on the physical and fire-retardant properties of the wood species. Hence, the use of fire-retardant treatment is of key interest to both wood industries and wood users while processing wood for building and other structural applications.
Keywords: Diammonium phosphate, fire retardants, phosphoric acid, physical properties, and volumetric swelling