1、Designation: D 5516 03Standard Test Method forEvaluating the Flexural Properties of Fire-Retardant TreatedSoftwood Plywood Exposed to Elevated Temperatures1This standard is issued under the fixed designation D 5516; the number immediately following the designation indicates the year oforiginal adopt
2、ion or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method is designed to determine the effect ofexposure to high
3、temperatures and humidities on the flexureproperties of fire-retardant treated softwood plywood. In thistest method, plywood is exposed to a temperature of 77C(170F).1.2 The purpose of the test method is to compare theflexural properties of fire-retardant treated plywood relative tountreated plywood
4、. The results of tests conducted in accor-dance with this test method provide a reference point forestimating strength temperature relationships. This test methodis intended to provide an accelerated test at elevated tempera-tures and controlled humidities of plywood sheathing treatedwith the same c
5、hemical formulation(s) and processing condi-tions as plywood used commercially.1.3 The values stated in SI units are to be regarded as thestandard. The values in parentheses are for information only.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its
6、use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D9 Terminology Relating to Wood2D 1165 Nomenclature of Domestic Hardwoods
7、and Soft-woods2D 2915 Practice for Evaluating Allowable Properties forGrades of Structural Lumber2D 3043 Test Methods for Structural Panels in Flexure2D 5516 Test Methods for Evaluating the Mechanical Prop-erties of Fire-Retardant Treated Softwood Plywood Ex-posed to Elevated Temperatures2D 6305 Pra
8、ctice for Calculating Bending Strength DesignAdjustment Factors for Fire-Retardant Plywood WoodSheathing2E84 Test Method for Surface Burning Characteristics ofBuilding Materials3E 176 Terminology of Fire Standards32.2 Other Standards:AWPA C27 Plywood-Fire Retardant Treatment by Pres-sure Processes4U
9、.S. Product Standard PS1 for Construction and IndustrialPlywood5NFPA 703 Standard for Fire Retardant Impregnated Woodand Fire Retardant Coatings for Building Materials63. Terminology3.1 DefinitionsDefinitions used in this test method are inaccordance with Terminologies D 9 and E 176, and Nomencla-tu
10、re D 1165.3.2 Definitions of Terms Specific to This Standard:3.2.1 depth of beamthat dimension of the beam which isperpendicular to the span and parallel to the direction in whichthe load is applied.3.2.2 spanthe total distance between the centerline ofsupports providing the reactions on which a bea
11、m is supportedto accommodate a transverse load.3.2.3 span-depth ratiothe numerical ratio of span dividedby beam depth.4. Summary of Test Method4.1 After preconditioning (see 6.5), matched specimens oftreated and untreated plywood will be exposed to 77C (170F)temperature and relative humidity equal t
12、o or greater than50 %.4.2 Flexural strength tests are conducted on exposed speci-mens removed after various time periods. Flexural strengthresults shall include maximum moment, bending stiffness, andwork to maximum load. Adjust the test results to 67 % relativehumidity. (See X1.2.)1This test method
13、is under the jurisdiction of ASTM Committee D07 on Woodand is the direct responsibility of Subcommittee D07.07 on Fire Performance ofWood.Current edition approved April 10, 2003. Published June 2003. Originallyapproved in 1991 as ES 20 91. Last previous edition approved in 2002 asD 5516 02.2Annual B
14、ook of ASTM Standards, Vol 04.10.3Annual Book of ASTM Standards, Vol 04.07.4Available from American Wood-Preservers Assoc., P.O. Box 5690, Granbury,TX 760490690.5Available from U.S. Department of Commerce, Washington, DC.6Available from National Fire Protection Association, P.O. Box 9191, Quincy,MA
15、02269-9101.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.3 The purpose of this test method is to determine the ratioof the treated mean to the untreated mean for the plywood andplot the accelerated exposure strength data against
16、exposuretime.5. Significance and Use5.1 The flexural properties evaluated by this test method areintended to provide any one or all of the following:5.1.1 Data on the comparative effects of fire-retardantchemical formulations and environmental conditions on theflexural properties of plywood.5.1.2 Da
17、ta for use in developing modification factors for theallowable design properties of treated plywood when exposedto elevated temperatures and humidities.5.1.3 Data comparing variables, such as other plywoodspecies and dimensions.5.2 Results obtained from tests conducted and analyzed inaccordance with
18、 the procedures of this test method may beused with other information to establish recommended roofsheathing spans for fire-retardant treated plywood.NOTE 1Temperatures lower than the test temperature specified in thistest method and the cumulative effects of the elevated temperatures andhumidity ex
19、posures expected to be encountered in service should be takeninto account when recommended roof sheathing spans are established.6. Test Specimens6.1 Material Selection:6.1.1 Source panels for this test shall be selected fromcommercially available 3, 4, or 5 ply panels of a singlethickness, grade and
20、 construction. The nominal panel thicknessshall be between 12 (1532 in.) and 16 mm (58 in.).NOTE 2Southern pine is suggested as the test material because itrequires higher fire-retardant chemical retentions to obtain the same flamespread rating compared to other softwood plywood species. Because the
21、bending strength of treated plywood correlates to the chemical retentionlevels, Southern pine plywood is believed to represent a worst casescenario for the same chemical formulation and treating/redrying proce-dures. Thus, evaluation of other species of plywood by testing of thatspecies, rather than
22、 by application of southern pine test results, areconsidered to be indicative of that species only.6.1.2 Select as source materials panels that provide bendingstrength specimens after cutting with clear essentially straight-grained faces free of scoring or other manufacturing defects.The inner plies
23、 shall be free of voids, core gaps, and core laps.Panels shall have generally uniform grain orientation andpercent latewood along and across the panel faces.Aminimumof six sheets of plywood meeting this description is required.Alternate 610 mm (2 ft) long sections to be treated and adjacentuntreated
24、 610 mm (2 ft) sections (see Fig. 1) shall have visuallysimilar wood quality.6.1.2.1 Specimens shall be inspected and the culling ofspecimens done as necessary in accordance with the criteria in7.3.4.NOTE 3A minimum of six sheets of plywood is required but cullingof specimens may require more sheets
25、.6.1.3 The specimen cutting pattern and numbering sequenceis shown in Fig. 1. Each panel of plywood is to be labeled witha number from 1 to 6. Cut each sheet crosswise to provide 610mm by 1220-mm (2 by 4-ft) sections. Each section is labeledwith the sheet number and letter A, B, C, or D. The A and C
26、sections of each of the six panels is to be treated, while the Band D sections of the six panels are to remain untreated.6.2 Treatment:6.2.1 Pressure treat the A and C section of each of the sixplywood panels with the fire-retardant formulation beingtested. The gage retention level of each charge sh
27、all not be lessthan the value midway between the middle of the retentionrange and the maximum retention as specified by the agencycertifying the flame spread index of the treated plywood. Theretention range specified by the certifying agency shall providea flame-spread index of 25 or less when teste
28、d in accordancewith Test Method E84 for 10 min, show no evidence ofsignificant progression combustion when the test is continuedfor an additional 20-min period, and not allow progression ofthe flame front beyond a distance of 3.2 m (10.5 ft) beyond thecenterline of the burners anytime during the 30-
29、min extendedtest.6.2.1.1 The provisions of 6.2.1 are not intended to preventuse of this test method when the fire-retardant treatments beingcertified are for applications other than those requiring con-formance to AWPA Standard C-27, NFPA Standard 703, orsimilar building code requirements for “fire-
30、retardant-treatedwood” that require the Test Method E84test extended to 30min. When alternative performance criteria for the treatmentare being certified, the test report on specimens of thattreatment shall state clearly the alternative performance criteriaand that the treatment retention was limite
31、d to that required forthe alternative performance criteria.6.2.2 Weigh all plywood sections before and immediatelyafter treatment to determine the chemical retention based onthe solution retained and the concentration of chemicals in thesolution. Complete a treating report for each charge of materia
32、lto ducument the treating cycle, times, pressures and plywoodretentions.6.3 Post-Treatment Drying:6.3.1 After pressure treatment, kiln dry the twelve treatedplywood sections to a maximum moisture content of 15 %following the standard redrying procedures established for thetreatment by the manufactur
33、er. Redry the sections at themanufacturers maximum specified dry bulb temperature withFIG. 1 Plywood Cutting PatternD5516032a minus 2C (4F) tolerance for 21 h of the first 24-h period.For the remainder of the drying period, the tolerance shall beminus 3C (5F). There is no upper limit on the redrying
34、temperature. Sticker all plywood sections to obtain proper airflow across the panels and to provide even drying. If themanufacturers procedures permit double stacking of panelsintended for structural application, treated plywood test sec-tions also shall be double stacked rather than stickered indi-
35、vidually.NOTE 4Research has shown that high kiln drying temperatures canadversely affect the structural properties of wood products. The AmericanWood-Preservers Association (AWPA) and National Fire ProtectionAssociation (NFPA) standards for fire retardant treated wood productslimit kiln dry bulb tem
36、peratures. AWPA Standard C27 requires that thedry bulb temperature of the kiln not exceed 70C (160F) during any kilndrying of plywood treated with fire retardants. In the case of exterior fireretardants that require curing at higher temperatures, curing after themoisture content is 15 % or less is p
37、ermitted. However, such elevatedcuring temperatures must not exceed 99C (210F) and the total curingtime must not exceed 48 h. In NFPA Standard 703, the dry bulbtemperature must not exceed 70C (160F) until the average moisturecontent of the wood has dropped to 25 % or less.NOTE 5To establish the wors
38、t-case flexural properties of treatedsoftwood plywood, the laboratory must redry the test material within asmall negative tolerance of the maximum temperature used by themanufacturer. Therefore, there is no upper limit for the temperature usedin the tests. If a manufacturer desires to establish cons
39、ervative propertyvalues or provide a basis for evaluating production material that exceedsthe limit, the test material can be redried at that temperature. Amanufacturer then is allowed to determine the necessary productionschedule for their treatment and equipment or conditions. Thus, a steppedsched
40、ule, (for example, 10 h at 54C (130F), 10 h at 60C (140F), 10 hat 71C (160F), etc.) is allowed by the standard, provided the maximumtemperature tolerance requirement is met. These provisions provide forair-drying production material provided the redry conditions for the testmaterials are within the
41、tolerance of the maximum temperature specifiedby the manufacturer.6.3.2 Monitor the moisture content of the plywood sectionsduring the drying cycle by individually weighing the sections.The sections shall not be damaged or warped during the dryingprocess. Keep a well-documented kiln charge report an
42、d kilnrecorder chart showing temperatures and humidities on thedried material.6.4 Specimen Preparation:6.4.1 After drying, cut the treated and untreated 610 by1220-mm (2 by 4-ft) sections into nominal 75 by 610-mm (3 by24-in.) test specimens as shown on Fig. 1. Alternatively,specimen sizes in accord
43、ance with Test Methods D 3043,Method A shall be used instead of this size. Number thesespecimens consecutively from 1 to 14, creating 168 treated and168 untreated specimens. Randomly select 20 of the 168untreated and treated specimens as unexposed controls. Theremaining 148 treated and 148 untreated
44、 specimens shall berandomly assigned to 7 sets of 20 specimens for both thetreated and untreated material. These are subjected to exposurefollowed by strength testing. This results in 8 treated and 8untreated specimens not assigned to any set for testing (seeNote 6).NOTE 6The 168 treated and 168 unt
45、reated specimens (6.4.1) are 48more specimens than are needed to be tested. The resulting two extra setsof 20 can be saved as replacement sets if the number of specimens in a setdrops below the minimum of 18 (7.3.4). Alternatively, the extra 48specimens can be used to increase the number of specimen
46、s in each set.Asample size of 28 allows one to estimate a 75 % confidence interval for the5 % nonparametric tolerance limit (see Practice D 2915).6.4.1.1 Alternatively, the variation in the mean response canbe reduced by a blocked specimen selection where each treatedspecimen is end-matched to an un
47、treated specimen from thesame original panel. If blocking is used and a specimen iseliminated either before or after testing, then its mate shall alsobe eliminated.76.5 PreconditioningEquilibrate all sets of treated anduntreated specimens at an ambient temperature and relativehumidity to achieve an
48、equilibrium moisture content in theuntreated specimens of 10 6 2 %. Specimens are considered tobe at equilibrium moisture content when a constant weight hasbeen achieved. A constant weight is assumed when twoconsecutive weighings at a 24-h interval differ by no more than60.2 %.7. Procedure7.1 Specim
49、en Exposure:7.1.1 After preconditioning, test the unexposed controls (see6.4.1) as described in 7.3 for initial, unexposed bendingstrength properties.7.1.2 Expose all the remaining treated and untreated speci-men sets in a chamber controlled to 77 6 1C (170 6 2F) anda minimum of 50 % relative humidity. The control of therelative humidity in the chamber shall be 64 % and average61 % around the set point.7.1.3 The first set of 20 untreated and 20 treated specimensshall be subjected to flexural test after 14 days exposure in the77C (170F) chamb
