Robert H. White

Physical, mechanical, and fire properties of oriented strandboard with fire retardant treated veneers

AbstractThis study evaluated physical, mechanical and fire properties of oriented strand boards (OSB) coveredn with fire retardant treated veneers. The beech (Fagus orientalis Lipsky)n veneers were treated with either monoammonium phosphate, diammonium phosphate, lime water or axa0borax/boricn acid (1:1 by weight) mixture. Physical and mechanical properties of the specimens were performed accordingn to EN and DIN standards. Axa0cone calorimeter was used to determine their combustion characteristics.n The physical and mechanical properties of the specimens were adversely affected by the treatments. Then specimens treated with lime water had the best physical performance while the specimens treated withn borax/boric acid had the highest mechanical properties. The fire retardant treatments of the face veneersn were effective in reducing the initial contribution of heat release to potential fire growth. In particular,n the lime water treatment was an effective fire retardant treatment in that it reduced both the effectiven heat of combustion and the mass loss rate. It also delayed the times for sustained ignition.n ZusammenfassungIn dieser Studie wurden die physikalischen und mechanischen sowie die Brandeigenschaften von OSBn mit Feuerschutzmittel imprägnierten Deckfurnieren untersucht. Die Buchenfurniere (Fagusn orientalis Lipsky) wurden entweder mit Monoammoniumphosphat, Diammoniumphosphat, Kalkwassern oder einer Borax/Borsäure-Mischung (im Gewichtsverhältnis 1:1) imprägniert. Physikalischen und mechanische Eigenschaften der Proben wurden nach EN- und DIN-Normen untersucht. Das Brandverhaltenn wurde mittels einer Cone-Calorimeter-Prüfung bestimmt. Die Imprägnierung wirkte sich auf dien physikalischen und mechanischen Eigenschaften der Proben nachteilig aus. Die mit Kalkwasser imprägniertenn Proben wiesen die besten physikalischen Eigenschaften auf, wohingegen die mit Borax/Borsäure imprägniertenn Proben die besten mechanischen Eigenschaften hatten. Durch die Feuer hemmende Behandlung der Deckfurnieren wurde die Wärmefreisetzung verzögert. Dabei erwies sich die Imprägnierung mit Kalkwassern als besonders wirksam, da sie sowohl die Gesamtwärmefreisetzung als auch die Masseverlustrate reduzierte.n Daneben verzögerte sie auch den Entzündungszeitpunkt.n

Analytical Methods for Determining Fire Resistance of Timber Members

The fire resistance ratings of wood members and assemblies, as with other materials, have traditionally been obtained by testing the assembly in a furnace in accordance with ASTM International (ASTM) Standard E119 “Standard test methods for fire tests of building construction and materials”, International Organization for Standardization (ISO) Standard 834 “Fire-resistance tests-Elements of building construction”, and similar standards. In the U.S., these ratings are published in listings, such as Underwriters Laboratories Fire Resistance Directory, Gypsum Association’s Fire Resistance Design Manual, American Wood Council’s Design for Code Acceptance publications, and those in building codes. The ratings listed are limited to the actual assembly tested and normally do not permit modifications such as adding insulation, changing member size, changing interior finish, or increasing the spacing between members. Code interpretation of test results sometimes allows the substitution of larger members, thicker or deeper assemblies, smaller member spacing, and thicker protection layers, without reducing the listed rating.

Application of CMA program to wood charring

Experiments were conducted to test the ability of a computer program to describe the charring of ovendried wood.

Modelling the charring behaviour of structural lumber

Charring rates for large-section timber based on experimental data have been generally established. The established rates may not be appropriately used for the prediction of failure times of lumber members which are small by comparison. It is questionable whether a constant rate can be safely assumed for lumber members since the rate is likely to increase once the centre-point temperature of the members starts to rise. This paper presents an empirically based model of charring rates for Spruce-Pine-Fir (SPF) Machine-Stress-Rated (MSR) 2X4 lumber subjected to a constant-temperature exposure of 500 degrees C, on the basis of test results on 55 specimens. In order that the model can be used with reliability analysis, one of the two model parameters was treated as a Lognormal random variable to explain variations observed in the charring rates. Furthermore, the model has been extended to permit evaluations for other lumber sizes and under exposures such as ASTM E119 fire conditions. The model was compared with existing models and used to predict char data found in the literature.