1、Designation: D 5516 09Standard 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 () 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 t
3、emperatures 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 ch
5、emical formulation(s) and processing condi-tions as plywood used commercially.1.3 The values stated in SI units are to be regarded asstandard. The values given in parentheses are mathematicalconversions to inch-pound units that are provided for informa-tion only and are not considered standard.1.4 T
6、his standard does not purport to address all of thesafety concerns, if any, associated with its 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 Docume
7、nts2.1 ASTM Standards:2D9 Terminology Relating to Wood and Wood-Based Prod-uctsD 1165 Nomenclature of Commercial Hardwoods and Soft-woodsD 2915 Practice for Evaluating Allowable Properties forGrades of Structural LumberD 3043 Test Methods for Structural Panels in FlexureD 6305 Practice for Calculati
8、ng Bending Strength DesignAdjustment Factors for Fire-Retardant-Treated PlywoodRoof SheathingE84 Test Method for Surface Burning Characteristics ofBuilding MaterialsE 176 Terminology of Fire Standards2.2 Other Standards:AWPA C-27 Plywood-Fire RetardantTreatment by PressureProcesses3NFPA 703 Standard
9、 for Fire Retardant Impregnated Woodand Fire Retardant Coatings for Building Materials4PS 1 U.S. Product Standard for Structural Plywood5PS 2 U.S. Product Standard for Wood-Based Structural UsePanels53. Terminology3.1 DefinitionsDefinitions used in this test method are inaccordance with Terminologie
10、s D9and E 176 and Nomencla-ture 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
11、 the reactions on which a beam 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
12、and relative humidity equal to or greater than50 %.4.2 Flexural strength tests are conducted on exposed speci-mens removed after various time periods. Flexural strength1This test method is under the jurisdiction of ASTM Committee D07 on Woodand is the direct responsibility of Subcommittee D07.07 on
13、Fire Performance ofWood.Current edition approved May 15, 2009. Published June 2009. Originallyapproved in 1991 as ES 20 91. Last previous edition approved in 2003 asD 5516 03.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For
14、 Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American Wood Protection Association (AWPA), P.O. Box361784, Birmingham, AL 35236-1784, http:/.4Available from National Fire Protection Association (NFPA), 1 Batterymarch
15、Park, Quincy, MA 02169-7471, http:/www.nfpa.org.5Available from the U.S. Department of Commerce, 1401 Constitution Ave.,NW Washington, DC 20230, http:/ts.nist.gov/Standards/Conformity/vps.cfm.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United
16、States.results shall include maximum moment, bending stiffness, andwork to maximum load. Adjust the test results to 67 % relativehumidity. (See X1.2.)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 exposur
17、e strength data against 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 proper
18、ties of plywood.5.1.2 Data 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 an
19、alyzed inaccordance with 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 tem
20、peratures andhumidity exposures 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 from grademarked PS 1 or PS 2 commercially available 3,
21、4, or 5 plypanels of a single thickness, grade, construction, and bonddurability. The nominal panel thickness shall be between 12mm (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 flam
22、espread rating compared to other softwood plywood species. Because thebending 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, evaluat
23、ion of other species of plywood by testing of thatspecies, rather than by application of southern pine test results, areconsidered to be indicative of that species only.6.1.2 Select source panels that provide bending strengthspecimens after cutting with clear essentially straight-grainedfaces free o
24、f scoring or other manufacturing defects. The innerplies shall be essentially free of voids, core gaps, and core laps(see 7.3.4.2). Panels shall have generally uniform grain orien-tation and percent latewood along and across the panel faces.Aminimum of six sheets of plywood meeting this description
25、isrequired. Alternate 610 mm (2 ft) long sections to be treatedand adjacent untreated 610 mm (2 ft) sections (see Fig. 1) shallhave visually similar 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
26、 of six sheets of plywood is required but cullingof specimens may require more sheets.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) section
27、s. Each section is labeledwith the sheet number and letter A, B, C, or D. The A and Csections 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 t
28、he fire-retardant formulation beingtested. The gage retention level of each charge shall 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 specifie
29、d by the certifying agency shall providea flame-spread index of 25 or less when tested 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 d
30、istance of 3.2 m (10.5 ft) beyond thecenterline of the burners anytime during the 30-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 A
31、WPA C-27, NFPA 703, or similar building coderequirements for “fire-retardant-treated wood” that require theTest Method E84test extended to 30 min. When alternativeperformance criteria for the treatment are being certified, thetest report on specimens of that treatment shall state clearly thealternat
32、ive performance criteria and that the treatment retentionwas limited to that required for the alternative performancecriteria.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
33、 thesolution. Complete a treating report for each charge of materialto document 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 %FIG. 1 Plywood Cuttin
34、g PatternD5516092following the standard redrying procedures established for thetreatment by the manufacturer. Redry the sections at themanufacturers maximum specified dry bulb temperature witha minus 2C (4F) tolerance for 21 h of the first 24-h period.For the remainder of the drying period, the tole
35、rance shall beminus 3C (5F). There is no upper limit on the redryingtemperature. 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 tes
36、t sec-tions also shall be double stacked rather than stickered indi-vidually.NOTE 4Research has shown that high kiln drying temperatures canadversely affect the structural properties of wood products.TheAWPAandNFPAstandards for fire retardant treated wood products limit kiln dry bulbtemperatures. AW
37、PA C-27 requires that the dry bulb temperature of thekiln not exceed 70C (160F) during any kiln drying of plywood treatedwith fire retardants. In the case of exterior fire retardants that requirecuring at higher temperatures, curing after the moisture content is 15 % orless is permitted. However, su
38、ch elevated curing temperatures must notexceed 99C (210F) and the total curing time must not exceed 48 h. InNFPA 703, the dry bulb temperature must not exceed 70C (160F) untilthe average moisture content of the wood has dropped to 25 % or less.NOTE 5To establish the worst-case flexural properties of
39、 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 conservative propertyvalues or pr
40、ovide 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 steppedschedule (for example, 10 h at 54C
41、 (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 tolerance of the maximum tempe
42、rature specifiedby the manufacturer.6.3.2 Monitor the moisture content of the plywood sectionsduring the drying cycle by individually weighing the sections.Reduce as much as possible damage or warp during the dryingprocess by adequately supporting the sections. Keep a well-documented kiln charge rep
43、ort and kiln recorder chart detailingthe drying cycle and parameters.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 accordance with
44、 Test Methods D 3043, TestMethod 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 spe
45、cimens 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 untreat
46、ed 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 specimens in
47、 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 untrea
48、ted specimen from thesame original panel. If blocking is used and a specimen iseliminated either before or after testing, then its mate shall alsobe eliminated (1).66.5 PreconditioningEquilibrate all sets of treated anduntreated specimens at an ambient temperature and relativehumidity to achieve an
49、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 Specimen 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 control
