ASTM D5516-00
(Test Method)Standard Test Method for Evaluating the Flexural Properties of Fire-Retardant Treated Softwood Plywood Exposed to Elevated Temperatures
Standard Test Method for Evaluating the Flexural Properties of Fire-Retardant Treated Softwood Plywood Exposed to Elevated Temperatures
SCOPE
1.1 This test method is designed to determine the effect of exposure to high temperatures and humidities on the flexure properties of fire-retardant treated softwood plywood. In this test method, plywood is exposed to a temperature of 77oC (170oF).
1.2 The purpose of the test method is to compare the flexural properties of fire-retardant treated plywood relative to untreated plywood. The results of tests conducted in accordance with this test method provide a reference point for estimating strength temperature relationships. This test method is intended to provide an accelerated test at elevated temperatures and controlled humidities of plywood sheathing treated with the same chemical formulation(s) and processing conditions as plywood used commercially.
1.3 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D 5516 – 00 An American National Standard
Standard Test Method for
Evaluating the Flexural Properties of Fire-Retardant Treated
Softwood Plywood Exposed to Elevated Temperatures
This standard is issued under the fixed designation D 5516; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope AWPA C–27 Plywood-Fire Retardant Treatment by Pres-
sure Processes
1.1 This test method is designed to determine the effect of
2.3 Federal Standard:
exposure to high temperatures and humidities on the flexure
U.S. Product Standard PS1 for Construction and Industrial
properties of fire-retardant treated softwood plywood. In this
Plywood
test method, plywood is exposed to a temperature of 77°C
(170°F).
3. Terminology
1.2 The purpose of the test method is to compare the
3.1 Definitions—Definitions used in this test method are in
flexural properties of fire-retardant treated plywood relative to
accordance with Terminologies D 9 and E 176, and Nomencla-
untreated plywood. The results of tests conducted in accor-
ture D 1165.
dance with this test method provide a reference point for
3.2 Definitions of Terms Specific to This Standard:
estimating strength temperature relationships. This test method
3.2.1 depth of beam—that dimension of the beam which is
is intended to provide an accelerated test at elevated tempera-
perpendicular to the span and parallel to the direction in which
tures and controlled humidities of plywood sheathing treated
the load is applied.
with the same chemical formulation(s) and processing condi-
3.2.2 span—the total distance between the centerline of
tions as plywood used commercially.
supports providing the reactions on which a beam is supported
1.3 The values stated in SI units are to be regarded as the
to accommodate a transverse load.
standard. The values in parentheses are for information only.
3.2.3 span-depth ratio—the numerical ratio of span divided
1.4 This standard does not purport to address all of the
by beam depth.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Summary of Test Method
priate safety and health practices and determine the applica-
4.1 After preconditioning (see 6.5), matched specimens of
bility of regulatory limitations prior to use.
treated and untreated plywood will be exposed to 77°C (170°F)
2. Referenced Documents temperature and relative humidity equal to or greater than
50 %.
2.1 ASTM Standards:
4.2 Flexural strength tests are conducted on exposed speci-
D 9 Terminology Relating to Wood
mens removed after various time periods. Flexural strength
D 1165 Nomenclature of Domestic Hardwoods and Soft-
results shall include maximum moment, bending stiffness, and
woods
work to maximum load. Adjust the test results to 67 % relative
D 2915 Practice for Evaluating Allowable Properties for
2 humidity. (See X1.2.)
Grades of Structural Lumber
2 4.3 The purpose of this test method is to determine the ratio
D 3043 Methods of Testing Structural Panels in Flexure
of the treated mean to the untreated mean for the plywood and
D 3201 Test Method for Hygroscopic Properties of Fire-
2 plot the accelerated exposure strength data against exposure
Retardant Wood and Wood-Base Products
time.
E 84 Test Method for Surface Burning Characteristics of
Building Materials
5. Significance and Use
E 176 Terminology of Fire Standards
5.1 The flexural properties evaluated by this test method are
2.2 American Wood Preservers’ Association Standard:
intended to provide any one or all of the following:
5.1.1 Data on the comparative effects of fire-retardant
This test method is under the jurisdiction of ASTM Committee D-7 on Wood chemical formulations and environmental conditions on the
and is the direct responsibility of Subcommittee D07.07 on Fire Performance of
flexural properties of plywood.
Wood.
Current edition approved March 10, 2000. Published June 2000. Originally
published as ES 20 – 91. Last previous edition D 5516 – 99a. Available from American Wood-Preservers’ Assoc., P.O. Box 5690, Granbury,
Annual Book of ASTM Standards, Vol 04.10. TX 76049–0690.
3 5
Annual Book of ASTM Standards, Vol 04.07. Available from U.S. Department of Commerce, Washington, DC.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 5516
5.1.2 Data for use in developing modification factors for the
allowable design properties of treated plywood when exposed
to elevated temperatures and humidities.
5.1.3 Data comparing variables, such as other plywood
species and dimensions.
5.2 Results obtained from tests conducted and analyzed in
accordance with the procedures of this test method may be
used with other information to establish recommended roof
sheathing spans for fire-retardant treated plywood.
NOTE 1—Temperatures lower than the test temperature specified in this
test method and the cumulative effects of the elevated temperatures and
humidity exposures expected to be encountered in service should be taken
into account when recommended roof sheathing spans are established.
6. Test Specimens
FIG. 1 Plywood Cutting Pattern
6.1 Material Selection:
6.1.1 Test 3, 4, or 5-ply commercially available panels.
than the value midway between the middle of the retention
NOTE 2—Southern pine is suggested as the test material because it
range and the maximum retention as specified by the agency
requires higher fire-retardant chemical retentions to obtain the same flame
certifying the flame spread index of the treated plywood. The
spread rating compared to other softwood plywood species. Because the
retention range specified by the certifying agency shall provide
bending strength of treated plywood correlates to the chemical retention
a flame-spread index of 25 or less when tested in accordance
levels, Southern pine plywood is believed to represent a worst case
scenario for the same chemical formulation and treating/redrying proce-
with Test Method E 84 extended to 30 min, when the flame
dures. Thus, evaluation of other species of plywood by testing of that
spread progresses no more than 10.5 ft (3.2 m) beyond the
species, rather than by application of southern pine test results, are
center line of the burners during the extended test and shows no
considered to be indicative of that species only.
more evidence of significant progressive combustion.
6.1.2 Thickness shall not be less than 0.012 6 0.001 m ( ⁄32
6.2.2 Weigh all plywood sections before and immediately
1 5 1
6 ⁄32-in.) nor greater than 0.016 6 0.0005 m ( ⁄8 6 ⁄64-in. ).
after treatment to determine the chemical retention based on
6.1.3 Select as source materials panels that provide bending
the solution retained and the concentration of chemicals in the
strength specimens after cutting with clear essentially straight-
solution. Complete a treating report for each charge of material
grained faces free of scoring or other manufacturing defects.
to ducument the treating cycle, times, pressures and plywood
The inner plies shall be free of voids, core gaps, and core laps.
retentions.
Panels shall have generally uniform grain orientation and
6.3 Post-Treatment Drying:
percent latewood along and across the panel faces. A minimum
6.3.1 After pressure treatment, kiln dry the 12 treated
of six sheets of plywood meeting this description is required.
plywood sections to a moisture content of 10 to 12 % using the
Alternate 1.22-m (4-ft) wide sections to be treated and adjacent
manufacturer’s recommended procedures but in no case ex-
untreated 1.22–m (4-ft) sections shall have visually similar
ceeding the temperature limits specified in AWPA C-27.
wood quality. Sample sections may be specially fabricated or
Sticker all plywood sections to obtain proper air flow across the
selected from production.
panels and to provide even drying.
6.1.3.1 Specimens shall be inspected and the culling of
6.3.2 Monitor the moisture content of the plywood sections
specimens done as necessary in accordance with the criteria in
during the drying cycle by individually weighing the sections.
7.3.4.
The sections shall not be damaged or warped during the drying
process. Keep a well-documented kiln charge report and kiln
NOTE 3—A special 5-ply, 0.0158-m ( ⁄8-in.), unsanded N-grade South-
recorder chart showing temperatures and humidities on the
ern pine plywood has been used for this test. This type of plywood
minimizes voids in the laminates and the veneers are specially selected to dried material.
minimize knots and other natural defects.
6.4 Specimen Preparation:
NOTE 4—A minimum of six sheets of plywood is required but culling
6.4.1 After drying, cut the treated and untreated 0.61 by
of specimens may require more sheets.
1.22-m (2 by 4-ft) sections into nominal 0.076 by 0.61-m (3 by
6.1.4 The specimen cutting pattern and numbering sequence 24-in.) test specimens as shown on Fig. 1. Alternatively,
is shown in Fig. 1. Each panel of plywood is to be labeled with specimen sizes in accordance with Methods D 3043 shall be
a number from 1 to 6. Cut each sheet crosswise to provide 0.61 used instead of this size. Number these specimens consecu-
by 1.22-m (2 by 4-ft) sections. Each section is labeled with the tively from 1 to 14, creating 168 treated and 168 untreated
sheet number and letter A, B, C, or D. The A and C sections of specimens. Randomly select 20 of the 168 untreated and
each of the six panels is to be treated, while the B and D treated specimens as unexposed controls. The remaining 148
sections of the six panels are to remain untreated. treated and 148 untreated specimens shall be randomly as-
6.2 Treatment: signed to 7 sets of 20 specimens for both the treated and
6.2.1 Pressure treat the A and C section of each of the six untreated material. These are subjected to exposure followed
plywood panels with the fire-retardant formulation being by strength testing. This results in 8 treated and 8 untreated
tested. The gage retention level of each charge shall not be less specimens not assigned to any set for testing (see Note 5).
D 5516
NOTE 5—The 168 treated and 168 untreated specimens (6.4.1) are 48
more specimens than are needed to be tested. The resulting two extra sets
of 20 can be saved as replacement sets if the number of specimens in a set
drops below the minimum of 18 (7.3.4). Alternatively, the extra 48
specimens can be used to increase the number of specimens in each set. A
sample size of 28 allows one to estimate a 75 % confidence interval for the
5 % nonparametric tolerance limit (see Practice D 2915).
6.4.1.1 Alternatively, the variation in the mean response can
be reduced by a blocked specimen selection where each treated
specimen is end-matched to an untreated specimen from the
same original panel. If blocking is used and a specimen is
eliminated either before or after testing, then its mate shall also
be eliminated.
6.5 Preconditioning—Equilibrate all sets of treated and
untreated specimens at an ambient temperature and relative
humidity to achieve an equilibrium moisture content in the
untreated specimens of 10 6 2 %. Specimens are considered to
NOTE 1—UNT = Untreated and MAP = Monoammonium phosphate
be at equilibrium moisture content when a constant weight has
treated.
been achieved. A constant weight is assumed when two
FIG. 2 SYP Plywood Exposed at 170°F (77°C)
consecutive weighings at a 24-h interval differ by no more than
60.2 %.
7.3.2.2 Test span of 0.56 m (22 in.).
7. Procedure
7.3.2.3 Rotational end plates and lateral rotation of end
7.1 Specimen Exposure:
supports are optional. However, the end supports shall be
7.1.1 After preconditioning, test the unexposed controls (see
rounded if rotational end plates are not provided.
6.4.1) as described in 7.1.2 and 7.1.3 for initial, unexposed
7.3.2.4 Loading rate of 0.305 m/s (0.20 in./min).
bending strength properties.
7.3.3 Load and deflection data shall be collected up to the
7.1.2 Expose all the remaining treated and untreated speci-
maximum bending load and continued until the specimen can
men sets in a chamber controlled to 77 6 1°C (170 6 2°F) and
no longer withstand 50 % of the maximum load.
a minimum of 50 % relative humidity. The control of the
7.3.4 After testing, if a specimen has one or more of the
relative humidity in the chamber shall be 64 % and average
following characteristics at the location of failure measure and
61 % around the set point.
report these characteristics:
7.1.3 The first set of 20 untreated and 20 treated specimens
7.3.4.1 Average short grain steeper than 1:16 in the tension
shall be subjected to flexural test after 14 days exposure in the
ply or steeper than 1:8 in the compression ply;
77°C (170°F) chamber. Remove 4 additional sets of 20 treated
7.3.4.2 Core lap of any width;
and 20 untreated specimens at well-spaced, appropriate inter-
7.3.4.3 Core gap wider than 3.2 mm ( ⁄8) in.
vals to establish the slope of the line when the strength
7.3.4.4 These characteristics may be listed as reasons for
properties are plotted versus time. Experience has shown that
elimination of specimens from subsequent calculations. How-
removals at 2 to 3-week intervals for an exposure period of >75
ever, the minimum sample size is 18 specimens. Report
days are normally sufficient (Fig. 2 illustrates modulus of
strength data both with and without results from specimens
rupture (MOR) response with time).
containing these characteristics.
7.2 Postconditioning—After exposure to elevated tempera-
tures, postcondition all sets of treated and untreated specimens
8. Report
at an ambient temperature and relative humidity that allow the
8.1 Report the following information:
untreated specimens to equilibrate to a moisture content of 10
8.1.1 The average relative humidity and temperature for
6 2 %, using the same general procedure as for precondition-
each conditioning environment.
ing described earlier. Then equilibrate the treated specimens to
8.1.2 Thickness, specific gravity (oven-dry mass/volume at
whatever equilibrium moisture content these conditions pro-
test), test moisture content, modulus of elasticity, and modulus
duce.
of rupture for each specimen; as well as maximum moment,
7.3 Strength Testing—Flexural Properties:
stiffness, and work-to-maximum-load from the strength tests.
7.3.1 Test untreated and treated specimens for flexural
8.1.3 If one or more of the characteristics listed in 7.3.4
stiffness and strength using the general procedures specified in
exists at the location of failur
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