Effects of Fire Retardant Treatments on Wood Strength: A Review
Keywords:
Acid hydrolysis, fire retardants, plywood, strength, thermal degradationAbstract
As evidenced by recent structural problems with fire-retardant-treated plywood, fire retardant chemicals and high temperature environments can degrade the strength properties of wood. We do not know to what extent fire retardant chemicals, thermal environment, and moisture content contribute to wood degradation. We suspect that the combination of acidic fire retardant chemicals and elevated temperatures increases the rate of acid hydrolysis in the wood, thereby causing a loss in strength. This paper presents a review of the pertinent literature on the factors influencing strength reduction in treated wood. These factors are the thermal degradation process of wood, the mechanism by which fire retardant chemicals alter wood degradation, the effect of acids on wood strength, the influence of temperature on strength, and the combined effect of fire retardant chemicals and temperature on strength. We also discuss possible long-term effects of in-service conditions on the strength of treated wood; the effects of treatment on the strength of weaker structural members and on species, size, and grade of lumber; and the application of the relationship between treatment and strength to plywood and lumber.References
Adams, E. H., G. L. Moore, and J. D. Brazier. 1979. The effect of flame-retardant treatments on some mechanical properties of wood. BRE-IP 24/79. Building Research Establishment, Aylesbury, Bucks., U.K.nBarnes, H. M., and P. H. Mitchell. 1984. The effect of post-treatment redry schedule on the strength of CCA-treated southern pine dimension lumber. Forest Prod. J. 34(6):29-33.nBeall, F. C. 1971. Differential calometric analysis of wood and wood components. Wood Sci. Tech. 5:159-175.nBeall, F. C., and H. W. Eickner. 1970. Thermal degradation of wood components: A review of the literature. Res. Pap. FPL 130. U.S. Department of Agriculture, Forest Serv., Forest Prod. Lab., Madison, WI.nBendtsen, B. A., L. R. Gjovik, and S. Verril. 1983. The mechanical properties of salt-treated longleaf pine. Res. Pap. FPL 434. U.S. Department of Agriculture, Forest Serv., Forest Prod. Lab., Madison, WI.nBrenden, J. J. 1967. Effect of fire-retardant and other inorganic salts on pyrolysis products of ponderosa pine at 250° and 350°C. Res. Pap. FPL 80. U.S. Department of Agriculture, Forest Serv., Forest Prod. Lab., Madison, WI.nBroido, A., A. Javierson, and E. Barrall II. 1973. Molecular weight decreases in the early pyrolysis of crystalline and amorphous cellulose. J. Appl. Polymer Sci. 17(12):3627-3635.nBrowne, F. L. 1958. Theories of the combustion of wood and its control. USDA FPL Rep. 2136. Forest Prod. Lab., Madison, WI (reviewed and reaffirmed in 1963).nBrowne, F. L., and W. K. Tang. 1963. Effect of various chemicals in the thermogravimetric analysis of ponderosa pine. Res. Pap. FPL 6. U.S. Department of Agriculture, Forest Serv., Forest Prod. Lab., Madison, WI.nBublitz, W. J., and J. L. Hull. 1983. Chemical resistance of Douglas-fir for use in storage tanks. Wood Fiber Sci. 15(1):59-68.nCaulfield, D. F. 1985. A chemical kinetics approach to the duration-of-load problem in wood. Wood Fiber Sci. 15(1):59-68.nCech, M. Y., and D. R. Huffman. 1974. High-temperature drying for mixed spruce, jack pine, and balsam fir. Publ. 1337. Canadian Forest Serv., Eastern Forest Prod. Lab. Ottawa, Ont., Canada.nComstock, G. L. 1976. Comparison of mechanical properties of Douglas-fir and southern pine lumber dried by CRT, high temperature, and conventional schedules. In C. C. Gerhards and J. M. McMillan, eds. Proceedings, conference on high temperature drying effects on mechanical properties of softwood lumber. U.S. Department of Agriculture, Forest Serv., Forest Prod. Lab., Madison, WI.nCountryman, D. 1957. Effect on plywood strength of preservative treatment. Lab. Rep. 74. Douglas Fir Plywood Association, Tacoma, WA.nEllis, W. D., R. M. Rowell, S. L. LeVan, and A. Susott. 1987. Thermal degradation properties of wood reacted with diethylchlorophosphate or phenylphosphonic dichloride as potential flame retardants. Wood Fiber Sci. 19(4):439-445.nFengel, D., and Wegener, G. 1984. Reactions in acidic medium. Pages 268-292 in Wood. Chemistry, ultrastructure, reactions. Walter de Gruyter and Co., Berlin.nFung, D. P. C., Y. Tsuchiya, and K. Sumi. 1972. Thermal degradation of cellulose and levoglucosan—The effect of inorganic salts. Wood Sci. 5(1):38-43.nGerhards, C. C. 1970. Effect of fire-retardant treatment on bending strength of wood. Res. Pap. FPL 145. U.S. Department of Agriculture, Forest Serv., Forest Prod. Lab., Madison, WI.nGerhards, C. C. 1979. Effect of high-temperature drying on tensile strength of Douglas-fir 2 x 4's. Forest Prod. J. 29(3):39-46.nGerhards, C. C. 1982. Effect of moisture content and temperature on the mechanical properties of wood: An analysis of immediate effects. Wood Fiber 14(1):4-36.nGerhards, C. C. 1983. Effect of high-temperature drying on the bending strength of yellow-poplar 2 x 4's. Forest Prod. J. 33(2):61-67.nGraham, R. D. 1964. Strength of small Douglas-fir beams treated with fire retardants. American Wood-Preservers' Association 60:172-177.nHillis, W. E. 1975. The role of wood characteristics in high-temperature drying. J. Inst. Wood Sci. 7(2):60-67.nHirata, T. 1979. Changes in degree of polymerization and weight of cellulose untreated and treated with inorganic salts during pyrolysis. Forest and Forest Prod. Res. Inst. 304. J. Japan Wood Res. Soc. Bull.:77-124.nHoover Treated Wood Products. 1984. Personal communication with B. W. Holden, Vice President.nIfju, G. 1964. Tensile strength behavior as a function of cellulose in wood. Forest Prod. J. 14(8):366-372.nJessome, A. P. 1962. Strength properties of wood treated with fire retardants. Rep. 193. Forest Prod. Res. Branch, Dept. of Forestry, Canada.nJohnson, J. W. 1967. Bending strength for small joists of Douglas-fir treated with fire retardants. Rep. T-23. Oregon State University, Forest Res. Lab., Corvallis, OR.nKass, A., F. F. Wangaard, and H. A. Schroeder. 1970. Chemical degradation of wood: The relationship between strength retention and pentosan content. Wood Fiber Sci. 2(1):31-39.nKauman, W. G. 1962. Kinetics of changes in acidity during thermal degradation of wood from three Australian species. Forest Prod. J. 12(6):275-276.nKing, E. G., Jr., and D. A. Matteson, Jr. 1961. Effects of fire-retardant treatments on the mechanical properties of Douglas-fir plywood. Lab. Rep. 90. Douglas-fir Plywood Association. 14 pp.nKnuffel, W. E. 1985. The effect of CCA preservative treatment on the compression strength of South African pine structural timber. Holzforschung und Holzverwertung 37(5):96-99.nKoch, P. 1971. Process for straightening and drying southern pine 2 by 4's in 24 hours. Forest Prod. J. 21(5):17-24.nKoch, P. 1985. Drying southern pine at high temperature—A summary of research at Pineville, LA from 1963-1982. Pages 1-38 in P. H. Mitchell, ed. Proceedings, North American drying symposium. Mississippi Forest Products Utilization Laboratory, Mississippi State University, Starkville, MS.nKoppers Co. 1985. Strength properties of DRICON treated wood. Product Data Sheet WOL-232. Koppers Co., Inc., Pittsburgh, PA.nKozlik, C. T. 1968. Effect of kiln-drying temperatures on strength of Douglas-fir and hemlock dimension lumber. Oregon State University, Forest Res. Lab., Corvallis, OR.nLadell, J. L. 1956. High-temperature drying of yellow birch. Forest Prod. J. 6(11):470-475.nLeVan, S. L. 1984. Chemistry of fire retardancy. In R. M. Rowell, ed. The chemistry of solid wood. Advances in Chemistry Series 207. American Chemical Society, Washington, DC.nLeVan, S. L., and C. A. Holmes. 1986. Effectiveness of fire-retardant treatments for shingles after 10 years of outdoor weathering. Res. Pap. FPL 474. U.S. Department of Agriculture, Forest Serv., Forest Prod. Lab., Madison, WI.nLyon, D. E., K. L. Bigbee, and W. S. McNamara. 1988. Evaluation of strength properties of fire-retardant treated wood using the 1983 National Forest Products Association protocol. Forest Prod. J. 38(6):13-18.nLyons, J. W. 1970. The chemistry and uses of fire retardants. Wiley-Interscience, New York.nMacKay, J. G. G. 1976. Effect of high temperature kiln-drying on lumber properties. Proceedings, research conference on high temperature drying effects on mechanical properties of softwood lumber. U.S. Department of Agriculture, Forest Serv., Forest Prod. Lab., Madison, WI.nMcDermott, J. B., M. T. Klein, and J. R. Obst. 1986. Chemical modeling in the deduction of process concepts: A proposed novel process for lignin liquefaction. I&EC Process Design and Development 25:885-889.nMerck Index. 1968. The Merck index: An encyclopedia of chemicals and drugs, 8th ed. P. G. Stecher, ed. Merck and Co., Rahway, NJ.nNational Forest Products Association. 1986. National design specification for wood construction. National Forest Products Association, Washington, DC.nOberley, W. J. U.S. Patent 4,373,010. February 8, 1983.nObst, J. R. 1983. Analytical pyrolysis of hardwood and softwood lignin and its use in lignin-type determination of hardwood vessel elements. J. Wood Chem. Tech. 3(4):377-397.nOsmose Company. 1984. Personal communication with J. C. Gauntt, Director of Codes and Product Acceptance, Osmose Company, Griffin, GA.nRasmussen, E. F. 1961. Dry kiln operator's manual. Agric. Handb. 188. U.S. Department of Agriculture, Forest Serv., Forest Prod. Lab., Madison, WI.nRietz, R. C., and R. H. Page. 1971. Air drying lumber: A guide to industry practice. Agric. Handb. 402. U.S. Department of Agriculture, Forest Serv., Forest Prod. Lab., Madison, WI.nSalamon, M. 1963. Quality and strength properties of Douglas-fir dried at high temperatures. Forest Prod. J. 13(8):339-344.nSalamon, M. 1969. High temperature drying and its effect on wood properties. Forest Prod. J. 19(3):27-34.nShafizadeh, F. 1968. Pyrolysis and combustion of cellulosic materials. In M. L. Wolfrom and R. S. Tipson, eds. Advances in Carbohydrate Chemistry 23:419-474. Academic Press, New York.nShafizadeh, F. 1971. Thermal behavior of carbohydrates. Part C. J. Polymer Sci. 36:21-51.nShafizadeh, F. 1975. Industrial pyrolysis of cellulosic materials. Applied Polymer Symposium 28:153-174.nShafizadeh, F. 1984. Pyrolysis and combustion. In R. M. Rowell, ed. The chemistry of solid wood. Advances in Chemistry Series 207. Chapter 13. American Chemical Society, Washington, DC.nShafizadeh, F, and P. S. Chin. 1977. Thermal deterioration of wood. In I. S. Goldstein, ed. Wood technology: Chemical aspects. ACS Symposium Series 43:57-81. American Chemical Society, Washington, DC.nShafizadeh, F, and Y. Sekiguchi. 1983. Development of aromaticity of cellulosic chars. Carbon 21:511-516.nSpringer, E. L. 1966. Hydrolysis of aspenwood with aqueous solutions of hydrochloric acid. TAPPI 49(3):102-106.nStamm, A. J. 1955. Thermal degradation of wood and cellulose. Presented at the symposium on degradation of cellulose and cellulose derivatives, 127th National Mtg., 1955 April 4-7, Cincinnati, OH. American Chemical Society, Division of Cellulose Chemistry.nTang, W. K. 1967a. Effect of inorganic salts on pyrolysis of wood, alpha-cellulose, and lignin determined by dynamic thermogravimetry. Res. Pap. FPL 71. U.S. Department of Agriculture, Forest Serv., Forest Prod. Lab., Madison, WI.nTang, W. K. 1967b. Effect of inorganic salts on pyrolysis of wood, cellulose, and lignin determined by differential thermal analysis. Res. Pap. FPL 82. U.S. Department of Agriculture, Forest Serv., Forest Prod. Lab., Madison, WI.nThompson, W. S. 1969. Effect of seasoning method on the strength properties of southern pine poles. Part I. Mechanical effects. Forest Prod. J. 19(1):21-28.nUSDA. 1987. Wood handbook: Wood as an engineering material. Agric. Handb. 72. U.S. Department of Agriculture, Washington, DC, 1987 rev.nWangaard, F. F. 1966. Resistance of wood to chemical degradation. Forest Prod. J. 16(2):53-64.nWinandy, J. E. 1988. Effects of treatment and redrying on mechanical properties of wood. Proceedings, FPRS conf. on wood protection and techniques and the use of treated wood in construction, 1987 October 28-30, Memphis, TN. Forest Prod. Res. Soc.:54-62.nWinandy, J. E. 1989. CCA preservative treatment and redrying effects on the bending properties of southern pine 2 by 4's. Forest Prod. J. 39(9):14-21.nWinandy, J. E., and R. S. Boone. 1988. The effects of CCA preservative treatment and redrying on the bending properties of 2 x 6 southern pine lumber. Wood Fiber Sci. 20(3):350-364.nWinandy, J. E., R. S. Boone, and B. A. Bendtsen. 1985. The interaction of CCA preservative treatment and redrying: Effects on the mechanical properties of southern pine. Forest Prod. J. 35(10):62-68.nWinandy, J. E., R. S. Boone, L. R. Gjovik, and P. L. Plantinga. 1989. The effects of ACA and CCA preservative treatment and redrying on the mechanical properties of Douglas-fir. Proceedings, Am. Wood Preservers' Assoc. Vol. 8.nWinandy, J. E., S. L. LeVan, E. L. Schaffer, and P. W. Lee. 1988. Effect of fire retardant treatment and redrying on the mechanical properties of Douglas-fir and aspen plywood. Res. Pap. FPL 485. U.S. Department of Agriculture, Forest Serv., Forest Prod. Lab., Madison, WI.nYao, J., and F. Taylor. 1979. Effect of high-temperature drying on the strength of southern pine dimension lumber. Forest Prod. J. 29(8):49-51.n
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