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Abstract
Although untreated plywood has given satisfactory performance as roof sheathing for more than 50 years, some fire-retardant plywood products have not performed satisfactorily in recent years. Thermally induced in-service failures have occurred with some fire-retardant-treated plywood roof sheathing. This paper describes the development and evaluation of a new test protocol for screening potential fire retardant treatments for plywood that is continuously or periodically exposed to elevated temperatures. In the protocol, untreated & monammonium-phospate-treated Southern Pine plywood specimens were exposed to various exposure temperatures and durations under steady state environments. All specimens were mechanically tested in either bending or tension. Monammonium-phosphate-treated plywood had lower bending and tension strength than did untreated plywood at all temperatures. The strength degradation rate of untreated & treated plywood increased as exposure temperature increased & appeared constant for any treatment-temperature combination (that is, linear over time). Within the RH limited studied, the magnitude of the RF effect did not appear to be as influentiaal as the tempeture effect. The results indicate the protocol provides an effective screening method for comparing the effects of extended exposure to elevated temperature on strength of untreated plywood and plywood treated with commercial fire-retardant formulations.
Although untreated plywood has given satisfactory performance as roof sheathing for more than 50 years, some fire-retardant plywood products have not performed satisfactorily in recent years. Thermally induced in-service failures have occurred with some fire-retardant-treated plywood roof sheathing. This paper describes the development and evaluation of a new test protocol for screening potential fire retardant treatments for plywood that is continuously or periodically exposed to elevated temperatures. In the protocol, untreated & monammonium-phospate-treated Southern Pine plywood specimens were exposed to various exposure temperatures and durations under steady state environments. All specimens were mechanically tested in either bending or tension. Monammonium-phosphate-treated plywood had lower bending and tension strength than did untreated plywood at all temperatures. The strength degradation rate of untreated & treated plywood increased as exposure temperature increased & appeared constant for any treatment-temperature combination (that is, linear over time). Within the RH limited studied, the magnitude of the RF effect did not appear to be as influentiaal as the tempeture effect. The results indicate the protocol provides an effective screening method for comparing the effects of extended exposure to elevated temperature on strength of untreated plywood and plywood treated with commercial fire-retardant formulations.
Date
6/1991
6/1991
Author(s)
J Winandy; S LeVan; R Ross; S Hoffman; CMcIntyre
J Winandy; S LeVan; R Ross; S Hoffman; CMcIntyre
Page(s)
21
21
Keyword(s)
plywood; roof sheathing; mechanical properties; strength effect; temperature; thermal effect; fire retardant
plywood; roof sheathing; mechanical properties; strength effect; temperature; thermal effect; fire retardant