Fire-Retardant-Treated Strandboard: Properties and Fire Performance

Authors

  • Jerrold E. Winandy
  • Qingwen Wang
  • Robert H. White

Keywords:

Strandboard, composites, fire retardant, treatment

Abstract

This study evaluated a series of single-layer, randomly oriented strandboard panels made with one resin type, a single resin loading level, and four fire-retardant-treatment levels. The fire retardant (FR) evaluated was a pH-buffered combination of boric acid and organic phosphate. Siberian larch strands were separated into five batches. One batch of strands served as the untreated control group and was not treated with water or FR; the four other batches were individually treated using a vacuum-pressure-soak process of the strands in water or three progressively higher concentrations of FR solutions. Targeted water- or FR-loading levels were no FR (0% FR-weight gain, water-treated control), 32 kg/m3 FR (~5% weight gain), 64 kg/m3 FR (~10% weight gain), and 96 kg/m3 FR (~15% weight gain). All water- or FR-treated strands were redried to less than 8% moisture content prior to diphenylmethane diisocyanate (MDI) resin application in rotary blenders using an aerosol sprayer. Three replicate specimens for each treatment level of 12.5-mm-thick, randomly oriented strandboard at a density of 650 kg/m3 were evaluated. FR-treated strandboard had higher dry- and wet-internal bond strength and lower flexural strength than matched untreated strandboard. A Class B flame-spread rating was achieved near 10% FR-loading. These results suggest that better ratings seem possible at higher loadings.

References

ASTM International. 2004a. Standard test method for heat and visible smoke release rates for materials and products using an oxygen consumption calorimeter. ASTM E 1354-04a. ASTM International, West Conshohocken, PA.nASTM International. 2004b. Standard test method for measurement of mass loss and ignitability for screening purposes using a conical radiant heater. ASTM E 2102-04a. ASTM International, West Conshohocken, PA.nASTM International. 2004c. Standard test method for surface burning characteristics of building materials. ASTM E 84-04. ASTM International, West Conshohocken, PA.nASTM International. 2005a. Standard test method for evaluating properties of wood-based fiber and particle panel materials. ASTM D 1037. ASTM International, West Conshohocken, PA.nASTM International. 2005b. Standard test method for FRT plywood exposed to elevated temperatures. ASTM D 5516. ASTM International, West Conshohocken, PA.nASTM International. 2005c. Standard practice for calculating bending strength design adjustment factors for fire-retardant-treated plywood roof sheathing. ASTM D 6305. ASTM International, West Conshohocken, PA.nDietenberger, M. A., and R. H. White 2001. Reaction-to-fire testing and modeling for wood products. Pages 54-69 in Twelfth Annual BCC Conference on Flame Retardancy, May 21-23, 2001, Stamford, CT. Business Communications Co., Inc., Norwalk, CT.nLevan, S., and M. Collet 1990. Choosing and applying fire-retardant-treated plywood and lumber for roof designs. General Technical Report FPL-GTR-62. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, Madison, WI. 13 pp.nLevan, S., R. Ross, and J. Winandy 1990. Effects of fire retardant chemicals on bending properties of wood at elevated temperatures. Research Paper FPL-RP-498. U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, Madison, WI. 26 pp.nNational Bureau of Quality and Technology Inspection. 1988a. Test method of difficult-flammability for building materials. China National Standard GB8625. Beijing, China.nNational Bureau of Quality and Technology Inspection. 1988b. Test method for density of smoke from the burning or decomposition of building materials. China National Standard GB8627. Beijing, China.nNational Bureau of Quality and Technology Inspection. 1997. Classification for burning behavior of building materials. China National Standard GB8624. Beijing, China.nNational Center of Inspection for Fixed Fire-Extinguishing System and Fire Retardant Components. 1999. Inspection Report No.YZ99300: Fire retardant FRW. Tianjin, China.nWang, Q-W., J. Li, and S-R. Zhang 1999. Synthesis of fire retardant for wood. Chinese National (CN) Patent No. 1213603A. Beijing, China.nWang, Q., W. Wang, and J. E. Winandy 2005. Effects of a new GUP-B fire retardant on mechanical properties of Korean pine when exposed to elevated temperature. Forest Prod. J. 55(12):214-220.nWhite, R. H. 2003. Fire resistance of engineered wood rim board products. Research Paper FPL-RP-610. U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, Madison, WI. 22 pp.nWhite, R. H., and M. A. Dietenberger 2004. Cone calorimeter evaluation of wood products. Pages 331-342 in Fifteen Annual BCC Conference on Flame Retardancy, June 7-9, 2004, Stamford, CT. Business Communications Co., Inc., Norwalk, CT.nWhite, R. H., and E. L. Schaffer 1981. Thermal characteristics of thick red oak flakeboard. Research Paper FPL-RP-407. U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, Madison, WI. 11 pp.nWhite, R. H., and J. E. Winandy 2006. Fire performance of oriented strandboard. Pages 297-309 in Proc. of the Conference on Recent Advances in Flame Retardancy of Polymeric Materials. BCC Research, Norwalk, CT. ISBN: 1-59623-221-8. Vol 17.nWhite, R. H., M.A. Dietenberger, H. Tran, O. Grexa, L. Richardson, K. Sumathipala, and M. Janssens 1999. Comparison of test protocols for the standard room/corner test. Fire and Materials 23:139-146.nWinandy, J. E. 2001. Serviceability modeling—Predicting and extending the useful service-life of FRT-plywood roof sheathing. Forest Prod. J. 51(2):47-54.nWinandy, J. E., H. M. Barnes, and C. A. Hatfield 2000. Roof temperature histories in matched attics in Mississippi and Wisconsin. Research Paper FPL-RP-589. U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, Madison, WI. 26 pp.n

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Published

2008-01-28

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Research Contributions