ASTM D7031-04
(Guide)Standard Guide for Evaluating Mechanical and Physical Properties of Wood-Plastic Composite Products
Standard Guide for Evaluating Mechanical and Physical Properties of Wood-Plastic Composite Products
SIGNIFICANCE AND USE
WPCs are intended for use in both structural and non-structural applications. The test methods described within are intended to address products that are manufactured from virgin or recycled wood and thermoplastic sources. These methods provide a reference for the evaluation of several mechanical and physical properties important for structural and non-structural uses of WPCs.
SCOPE
1.1 This guide covers test methods appropriate for evaluating a wide range of performance properties for wood-plastic composite (WPC) products. It was developed from evaluations of both experimental and currently manufactured products, and is not intended to suggest that all the tests listed are necessary or appropriate for each application of a WPC. The user must determine which test methods apply to the particular application being evaluated (see Appendix X1).
1.2 Details of manufacturing processes may be proprietary and are beyond the scope of this guide.
1.3 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:D7031–04
Standard Guide for
Evaluating Mechanical and Physical Properties of Wood-
Plastic Composite Products
This standard is issued under the fixed designation D7031; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope D1038 Terminology Relating to Veneer and Plywood
D1413 Test Method for Wood Preservatives by Laboratory
1.1 This guide covers test methods appropriate for evaluat-
Soil-Block Cultures
ing a wide range of performance properties for wood-plastic
D1554 Terminology Relating to Wood-Base Fiber and Par-
composite (WPC) products. It was developed from evaluations
ticle Panel Materials
of both experimental and currently manufactured products, and
D1761 Test Methods for Mechanical Fasteners in Wood
is not intended to suggest that all the tests listed are necessary
D1929 Test Method for Determining Ignition Temperature
or appropriate for each application of a WPC. The user must
of Plastics
determine which test methods apply to the particular applica-
D2017 Test Method of Accelerated Laboratory Test of
tion being evaluated (see Appendix X1).
Natural Decay Resistance of Woods
1.2 Details of manufacturing processes may be proprietary
D2047 Test Method for Static Coefficient of Friction of
and are beyond the scope of this guide.
Polish-Coated Flooring Surfaces as Measured by the
1.3 This standard does not purport to address all of the
James Machine
safety concerns, if any, associated with its use. It is the
D2394 Test Methods for Simulated Service Testing of
responsibility of the user of this standard to establish appro-
Wood and Wood-Base Finish Flooring
priate safety and health practices and determine the applica-
D2395 Test Methods for Specific Gravity of Wood and
bility of regulatory limitations prior to use.
Wood-Based Materials
2. Referenced Documents
D2481 Test Method for Accelerated Evaluation of Wood
Preservatives for Marine Services by Means of Small Size
2.1 ASTM Standards:
Specimens
C1308 Test Method for Accelerated Leach Test for Diffu-
D2565 Practice for Xenon-Arc Exposure of Plastics In-
sive Releases from Solidified Waste and a Computer
tended for Outdoor Applications
Program to Model Diffusive, Fractional Leaching from
D2915 Practice for Evaluating Allowable Properties for
Cylindrical Waste Forms
Grades of Structural Lumber
D9 Terminology Relating to Wood and Wood-Based Prod-
D3345 TestMethodforLaboratoryEvaluationofWoodand
ucts
Other Cellulosic Materials for Resistance to Termites
D143 Test Methods for Small Clear Specimens of Timber
D4000 Classification System for Specifying Plastic Materi-
D696 Test Method for Coefficient of Linear Thermal Ex-
als
pansion of Plastics Between Ø30°C and 30°C with a
D4060 Test Method for Abrasion Resistance of Organic
Vitreous Silica Dilatometer
Coatings by the Taber Abraser
D792 Test Methods for Density and Specific Gravity (Rela-
D4092 Terminology for Plastics: Dynamic Mechanical
tive Density) of Plastics by Displacement
Properties
D883 Terminology Relating to Plastics
D4442 Test Methods for Direct Moisture Content Measure-
D1037 Test Methods for Evaluating Properties of Wood-
ment of Wood and Wood-Base Materials
Base Fiber and Particle Panel Materials
D4495 Test Method for Impact Resistance of Poly(Vinyl
Chloride) (PVC) Rigid Profiles by Means of a Falling
Weight
This guide is under the jurisdiction ofASTM Committee D07 on Wood and is
D4761 Test Methods for Mechanical Properties of Lumber
the direct responsibility of Subcommittee D07.02 on Lumber and EngineeredWood
Products.
and Wood-Base Structural Material
Current edition approved Oct. 1, 2004. Published October 2004. DOI: 10.1520/
D5379/D5379M Test Method for Shear Properties of Com-
D7031-04.
2 posite Materials by the V-Notched Beam Method
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
D5456 SpecificationforEvaluationofStructuralComposite
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
Lumber Products
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D7031–04
D5764 TestMethodforEvaluatingDowel-BearingStrength
of Wood and Wood-Based Products
D6109 Test Methods for Flexural Properties of Unrein-
forced and Reinforced Plastic Lumber and Related Prod-
ucts
D6662 Specification for Polyolefin-Based Plastic Lumber
Decking Boards
E84 Test Method for Surface Burning Characteristics of
Building Materials
E108 Test Methods for Fire Tests of Roof Coverings
E661 Test Method for Performance of Wood and Wood-
Based Floor and Roof Sheathing Under Concentrated
L direction - Parallel to the longitudinal direction of the member (length)
X direction - Parallel to the wide surface of the member and normal to the L
Static and Impact Loads
direction (width)
E1354 Test Method for Heat and Visible Smoke Release
Y direction - Normal to both the L and X direction (thickness)
Rates for Materials and Products Using an Oxygen Con-
FIG. 1 Orientation for Wood-Plastic Composites
sumption Calorimeter
F1679 Test Method for Using a Variable Incidence Tribom-
methods provide a reference for the evaluation of several
eter (VIT)
mechanicalandphysicalpropertiesimportantforstructuraland
G154 Practice for Operating Fluorescent Light Apparatus
non-structural uses of WPCs.
for UV Exposure of Nonmetallic Materials
2.2 AWPA Standards:
5. Determination of Mechanical and Physical Properties
AWPA Standard E1 Standard Method for Laboratory
5.1 The following mechanical and physical properties are
Evaluation for Determination of Resistance to Subterra-
includedtoprovideacompletesetofreferencetestsforabroad
nean Termites
range of users. Some applications of WPCs will not require
AWPAStandard E7 Standard Method for Evaluating Wood
assessment of all properties. For example, products that will be
Preservatives by Field Tests with Stakes
limited to flexural applications will not require assessment of
tension or compression properties.
3. Terminology
5.2 Sampling—Samples for testing shall be representative
3.1 Definitions—Terminology used to describe WPCs is
ofthepopulationbeingevaluated.Samplingshallbeconducted
defined inTerminology D9, D883, D1038, D1554, D4092, and
in accordance with applicable portions of Practice D2915 and
Classification D4000.
be representative of the possible variations due to changes in
3.2 Definitions of Terms Specific to this Standard:
raw materials and process variables over time. It is essential to
3.2.1 recycled products—products composed of post-
consider batch-to-batch and shift-to-shift variability when
consumer material or recovered material, or both, that may or
sampling actual production. Test specimens shall be selected
may not have been subject to additional processing steps of the
from several production runs of a given item.
types used to make the products.
5.3 Sample Size—Selection of a sample size depends upon
3.2.2 thickness—the lesser dimension perpendicular to the
thepropertytobeestimated,theactualvariationintheproperty
long axis.
occurring in the population, and the precision with which the
3.2.3 virgin material —a material that has not been sub-
property is to be estimated. The principles of Practice D2915
jectedtouseorprocessingotherthanthatrequiredforitsinitial
shall be followed.
manufacture
NOTE 1—If code listed allowable design values or performance ratings
3.2.4 width—the greater dimension perpendicular to the
are the objective, it is recommended that all sampling and testing be
long axis.
conducted or witnessed, or both, by a qualified inspection agency.
3.2.5 wood-plastic composite (WPC)—a composite made
5.4 Conditioning—Prior to testing, all specimens shall be
primarily from wood- or cellulose-based materials and plas-
conditioned to environmental conditions appropriate for the
tic(s).
intended end use of the product.
3.3 Orientation—WPCs have three principal directions (see
5.4.1 Whentemperatureandrelativehumidityareimportant
Fig. 1).
considerations, the test specimens shall be conditioned for a
4. Significance and Use
period of time such that the average daily mass change of the
test specimen is less than 2 % of the mass at time of measure.
4.1 WPCs are intended for use in both structural and
5.4.2 When the product is to be subjected to a water soak
non-structural applications. The test methods described within
environment, the test specimens shall be tested within 30 min
are intended to address products that are manufactured from
upon removal from the treatment.
virgin or recycled wood and thermoplastic sources. These
5.5 Bending—Modulusofrupture(MOR)ormomentcapac-
ity and apparent modulus of elasticity (E) or flexural stiffness
Withdrawn. The last approved version of this historical standard is referenced
shall be determined in accordance with principles of Test
on www.astm.org.
Methods D4761 or D6109. For some applications and prod-
Available from American Wood-Preservers’ Association (AWPA), P.O. Box
388, Selma, AL 36702-0388, http://www.awpa.com. ucts, moment capacity and flexural stiffness are preferable
D7031–04
performance measures. Whenever possible, the test specimen 5.8 Compression Perpendicular to the L direction—
shall be the full cross section of the as-manufactured product. Compression strength perpendicular to the L direction shall be
Selection of specimen dimensions establishes the unit volume determined following the measurement and bearing require-
for analysis of volume effects in accordance with Specification ments of Test Method D143, except that the specimen dimen-
D5456, when applicable.Aspan-to-depth ratio of not less than
sions shall be the full cross-section dimension of theWPC, and
16 shall be used. The specimens shall be loaded at a constant the length shall be three times the depth. Load shall be applied
strain rate of 1 % per minute (610 %).Average time to failure
through a metal bearing plate across the full width of the test
for each test configuration shall be recorded (see X1.5). A specimen. Stress at both 0.02 and 0.04 in. (0.5 and 1.0 mm) of
constant strain rate of 1 % per minute is achieved by using a
deformation shall be reported. Testing shall be conducted with
constant rate of test machine cross-head motion, R, (inches/ stresses applied normal to the L-X or L-Y plane, or both, when
minute) computed in terms of the test span, L, and the member
required for general product application. The objective of this
depth, d, by the following equation: test is to determine the load carrying capacity of the as-
2 manufactured product. The allowable stress derived from this
L
R 5 0.00185 3
test will only apply to the actual cross section tested.
d
5.9 Shear Strength:
NOTE 2—WPCs often exhibit exceptionally large deformations prior to
5.9.1 Shear Parallel to the L direction (longitudinal shear)
failure in bending. Users are cautioned to take particular care in test
—Shear strength parallel to the L direction shall be determined
machine set-up to accommodate large deflections, both in terms of
deflection measuring devices and support conditions. in accordance with the principles of Test Method D143 using
the shear block test. Testing shall be done to produce shear
5.5.1 MOR—Maximum load for the calculation of MOR
failure in the L-X or L-Y plane, or both. For solid cross-section
shall be reported for each specimen. If the calculation is based
products,aminimumdimensionof1.0in.(25mm)intheshear
on a load other than the maximum load, the load basis shall be
area is acceptable provided that the total shear area is at least
reported.
1.0 in . For non-solid cross-section products, the full cross
NOTE 3—For products that exhibit large deformations, the MOR value
section shall be tested using the shear block tests with the
is commonly based on the load at 3 % strain.
actual shear area based on wall thickness(s) subjected to the
shearing stress.
5.5.2 E—Apparent flexural modulus of elasticity and its
calculation basis shall be reported for each specimen. Charac-
5.9.2 Shear Perpendicular to the L direction—Shear
terization of the modulus of elasticity depends upon the use of
strength perpendicular to the L direction shall be determined in
thedata.Formaterialpropertyinformation,Ecanbecalculated
accordance with the principles of Test Method D143 using the
in a variety of ways. For design value assignment purposes
shear block test. The Test Method D143 shear block test has
linear least squares fit of the stress-strain curve over an
been shown to provide a conservative estimate of the shear
appropriate range of stress shall be used.
strength of wood-based materials. Other test methods may be
applicable.Testing shall be done to produce shear failure in the
NOTE 4—To assign design values to structural members the least
X-Y plane. For solid cross-section products a minimum dimen-
squares fit over a range of 10 to 40 % of ultimate stress is commonly
sion of 1.0 in. (25 mm) in the shear area is acceptable provided
chosen as representative for service loadings. An alternative calculation
method based on the secant modulus to 1 % strain is commonly used for
that the total shear area is at least 1.0 in .
all-plastic products.
NOTE 5—For non-solid cross-section products, a shear block test
5.6 Tension Parallel to the L Direction—Tension strength
perpendicular to the L direction may not be practical. For some special
parallel to the L direction shall be evaluated by testing in
cases, such as nonhomogeneous materials or non-solid cross-section
products, alternative test methods such as Test Method D5379/D5379M,
accordance with the principles of Test Methods D4761. Speci-
will provide additional insight into actual shear strength material proper-
men cross section shall not be less than the minimum antici-
ties.
pated structural size. Specimen length between grips shall be a
minimum of 12 times the actual test specimen width. The
5.10 Creep-Recovery and Creep-Rupture:
specimens shall be loaded at a constant strain rate of 1 % per
NOTE 6—When building code listed design values are the objective of
minute (610 %).Average time to failure for each test configu-
the investigation, consideration of creep-recovery and creep-rupture are
ration shall be recorded. If required, selection of specimen
generally required.
dimensions establishes the unit volume for the analysis of
volume effects per Specification D5456. 5.10.1 Creep-Recovery—Aminimum of ten specimens re
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