ASTM D5574-94(2005)
(Test Method)Standard Test Methods for Establishing Allowable Mechanical Properties of Wood-Bonding Adhesives for Design of Structural Joints
Standard Test Methods for Establishing Allowable Mechanical Properties of Wood-Bonding Adhesives for Design of Structural Joints
SIGNIFICANCE AND USE
Safe and reliable mechanical properties for adhesives are necessary to achieve the full structural benefit of adhesives in bonded structural components and assemblies.
An adhesive’properties exhibit a natural variation or distribution of values. The allowable design stress for an adhesive must be adjusted to allow for variability and environmental effects to ensure human safety and prevent premature failure of costly structures.
Modification factors can be applied to the allowable design stress by the design engineer as deemed appropriate for the expected service conditions of the adhesive, or in accordance with the requirements of a building code.
The allowable properties developed under these methods apply only to the actual adhesive formulation tested and analyzed.
The allowable properties developed for a given adhesive shall apply only to adhesive bondlines with thicknesses in the range for which data is available.
SCOPE
1.1 These test methods cover the principles for establishing allowable mechanical properties for adhesives that can be used to design adhesive-bonded joints for structural components and assemblies of wood or wood with other materials. These test methods are modeled after Test Method D 245.
1.2 The properties determined are allowable shear stress, allowable tensile stress, and allowable shear modulus.
1.3 In determination of allowable shear- and tensile-stress levels, these test methods are limited by the horizontal shear and tension perpendicular-to-the-grain capacity of the wood adherends (hard maple, Acer saccharum, Marsh.). The adhesives so tested may actually have shear or tensile allowable stresses exceeding the wood, but the determined allowable design stress levels are limited (upper bounded) by the wood in these test methods. If a wood other than hard maple is used for testing the adhesive, then the allowable strengths are upper bounded by the properties of that particular wood.
1.4 The strength properties are determined by standard ASTM test methods. As a result, only procedural variations from the standards and special directions for applying the results are given in these test methods.
1.5 Time-to-failure data derived from creep-rupture testing (see Test Method D 4680) provide a measure of the ultimate strength of an adhesive bond as a function of time at various levels of temperature and moisture.
1.5.1 With proper caution, useful service life at a given shear stress level may be extrapolated from relatively short loading periods.
1.6 The resistance of the adhesive to permanent loss of properties due to aging (permanence) is assessed by means of strength tests after constant elevated-temperature and moisture aging of test specimens.
1.6.1 If the subject adhesives will be used to bond wood that has been treated with a preservative, fire retardant, or any other chemical to modify its properties, then the permanence of the adhesive shall be tested using wood adherends treated in the same manner.
1.7 Factors for durability, permanence, and creep derived by shear tests and analysis, are assumed to apply to tension (normal-to-the-bond) strength as well.
1.8 Requirements for production, inspection, and certification of adhesives evaluated under these test methods are not included.
1.9 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for infomration only and are not considered standard.
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Standards Content (Sample)
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Designation:D5574–94(Reapproved2005)
Standard Test Methods for
Establishing Allowable Mechanical Properties of Wood-
Bonding Adhesives for Design of Structural Joints
This standard is issued under the fixed designation D5574; 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 chemical to modify its properties, then the permanence of the
adhesive shall be tested using wood adherends treated in the
1.1 These test methods cover the principles for establishing
same manner.
allowable mechanical properties for adhesives that can be used
1.7 Factorsfordurability,permanence,andcreepderivedby
todesignadhesive-bondedjointsforstructuralcomponentsand
shear tests and analysis, are assumed to apply to tension
assemblies of wood or wood with other materials. These test
(normal-to-the-bond) strength as well.
methods are modeled after Test Method D245.
1.8 Requirements for production, inspection, and certifica-
1.2 The properties determined are allowable shear stress,
tion of adhesives evaluated under these test methods are not
allowable tensile stress, and allowable shear modulus.
included.
1.3 In determination of allowable shear- and tensile-stress
1.9 The values stated in inch-pound units are to be regarded
levels, these test methods are limited by the horizontal shear
as standard. The values given in parentheses are mathematical
and tension perpendicular-to-the-grain capacity of the wood
conversions to SI units that are provided for information only
adherends (hard maple, Acer saccharum, Marsh.). The adhe-
and are not considered standard.
sives so tested may actually have shear or tensile allowable
stresses exceeding the wood, but the determined allowable
2. Referenced Documents
design stress levels are limited (upper bounded) by the wood in
2.1 ASTM Standards:
these test methods. If a wood other than hard maple is used for
D245 Practice for Establishing Structural Grades and Re-
testing the adhesive, then the allowable strengths are upper
lated Allowable Properties for Visually Graded Lumber
bounded by the properties of that particular wood.
D897 Test Method for Tensile Properties of Adhesive
1.4 The strength properties are determined by standard
Bonds
ASTM test methods. As a result, only procedural variations
D905 Test Method for Strength Properties of Adhesive
from the standards and special directions for applying the
Bonds in Shear by Compression Loading
results are given in these test methods.
D907 Terminology of Adhesives
1.5 Time-to-failure data derived from creep-rupture testing
D1101 Test Methods for Integrity of Adhesive Joints in
(see Test Method D4680) provide a measure of the ultimate
Structural Laminated Wood Products for Exterior Use
strength of an adhesive bond as a function of time at various
D1151 Practice for Effect of Moisture and Temperature on
levels of temperature and moisture.
Adhesive Bonds
1.5.1 With proper caution, useful service life at a given
D2555 Practice for Establishing Clear Wood Strength Val-
shear stress level may be extrapolated from relatively short
ues
loading periods.
D2559 Specification for Adhesives for Structural Lami-
1.6 The resistance of the adhesive to permanent loss of
nated Wood Products for Use Under Exterior (Wet Use)
properties due to aging (permanence) is assessed by means of
Exposure Conditions
strength tests after constant elevated-temperature and moisture
D2915 Practice for Evaluating Allowable Properties for
aging of test specimens.
Grades of Structural Lumber
1.6.1 Ifthesubjectadhesiveswillbeusedtobondwoodthat
D3931 Test Method for Determining Strength of Gap-
has been treated with a preservative, fire retardant, or any other
FillingAdhesive Bonds in Shear by Compression Loading
These test methods are under the jurisdiction of ASTM Committee D14 on
Adhesives and are the direct responsibility of Subcommittee D14.70 on Construc-
tion Adhesives. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved April 1, 2005. Published April 2005. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
´1
approved in 1994. Last previous edition approved in 1999 as D5574–94(1999) . Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D5574-94R05. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D5574–94 (2005)
D3983 Test Method for Measuring Strength and Shear confidence interval on the fifth percentile as determined in
Modulus of Nonrigid Adhesives by the Thick-Adherend accordance with 7.1. (See lower 5 % tolerance limit.)
Tensile-Lap Specimen
3.2.4 basictensilestrength,n—anearminimumvalueofthe
D4027 Test Method for Measuring Shear Properties of tensile strength distribution determined as the one-sided lower
Structural Adhesives by the Modified-Rail Test
confidence interval on the fifth percentile as determined in
D4502 Test Method for Heat and Moisture Resistance of accordance with 9.1. (See lower 5 % tolerance limit.)
Wood-Adhesive Joints
3.2.5 creep factor, n—for modulus, the monotonic modulus
D4680 Test Method for Creep and Time to Failure of
as a function of loading rate expressed as the decimal fraction
Adhesives in Static Shear by Compression Loading
of the basic modulus.
(Wood-to-Wood)
3.2.6 creep factor, n—for strength, the estimated 30 year
D4896 Guide for Use ofAdhesive-Bonded Single Lap-Joint
creep rupture limit as a decimal fraction of the basic strength.
Specimen Test Results
3.2.7 delamination factor, n—a pass/fail factor based on the
IEEE/ASTM SI 10 Standard for Use of the International
percentage of delamination on the end grain of a laminate after
System of Units (SI): The Modern Metric System
cyclic delamination treatment.
3.2.7.1 Discussion—The factor is 0 or l: 0 if end-grain
3. Terminology
delamination is greater than 10 % of total end-grain bondline;
3.1 Definitions:
1 if less than 10 % after cyclic soak-dry treatment.
3.1.1 allowable design stress, n—a stress to which a mate-
3.2.8 durability factor, n—the average strength under el-
rial can be subjected under stated service conditions with low
evated test conditions expressed as a decimal fraction of the
probability of mechanical failure within the design lifetime.
strength at standard condition.
(D4896)
3.2.8.1 Discussion—Increases in temperature and moisture
3.1.1.1 Discussion—Allowable design stress is obtained by
level usually lower strength temporarily, as long as the speci-
multiplying the basic stress by a safety factor and possibly one
men is not so weakened that fracture occurs. Decreases in
or more modification factors as required by the intended
temperature and moisture level usually increase strength.
service environment.
Exceptions occur when increasing the temperature raises the
3.1.2 allowable shear stress, n—in an adhesive-bonded
level of adhesive cure and strength, or decreasing the tempera-
joint, the allowable design stress for structural joints subjected
ture or moisture induces brittleness and stress concentrations.
to shear force.
3.2.9 lower 5 % nonparametric tolerance limit [NTL],
3.1.3 allowable tensile stress, n—in an adhesive-bonded
n—an estimate of the one-sided lower confidence bond on the
joint, the allowable design stress for structural joints subjected
fifth percentile of the strength distribution determined as the
to tension force.
lowest ranked value (fast order statistic) of sample of speci-
3.1.4 creep rupture, n—the fracture of a material resulting
mens from a population.
from a sustained stress (or sum of stresses) above the creep
3.2.10 lower 5 % parametric tolerance limit [PTL], n—an
rupture limit.
estimate of the lower confidence bound on the fifth percentile
3.1.4.1 Discussion—The material may experience creep
of the strength distribution calculated as the mean of a sample
through the primary, secondary, and tertiary stages of rupture.
minus the sample standard deviation multiplied by a confi-
3.1.5 creep-rupture limit, n—the stress level below which
dence level factor.
creep rupture will not occur within a given time in a specified
3.2.11 lower 5 % tolerance limit, n— an estimate of the
environment. See creep rupture.
one-sided lower confidence bound on the fifth percentile of the
3.1.6 durability, n—as related to adhesive joints, the endur-
strength distribution of a population of specimens.
ance of joint strength relative to the required service condi-
3.2.12 modification factor, n—any external or internal fac-
tions. (D907)
tor of the service environment that temporarily or permanently
3.1.6.1 Discussion—Service conditions may include water
alters the strength or stiffness of an adhesive.
and other chemicals, temperature, stress, radiation, microor-
3.2.13 multiaxial stress, n—stress in two or three perpen-
ganisms, and other environmental factors.
dicular directions, bi- or triaxial stress.
3.1.7 permanence, n—the resistance of an adhesive bond to
3.2.13.1 Discussion—In most wood structures bonded with
deteriorating influences. (D907)
structural adhesives, multiaxial stress consists of a shear stress
3.1.8 structural adhesive, n—a bonding agent used for
in the plane of, and tension stress normal to the plane of the
transferring required loads between adherends exposed to
adhesive layer.
service environments typical for the structure involved.
3.2.14 permanence factor, n—the estimated residual
(D907)
strength at 30 years expressed as a decimal fraction of the
3.2 Definitions of Terms Specific to This Standard:
original strength at standard conditions.
3.2.1 allowable shear modulus, n—the modulus calculated
3.2.14.1 Discussion—This factor accounts for permanent,
in accordance with Section 14, that is used for the design of a
structural joint. usually long-term, changes in strength or modulus due to the
effects of factors such as heat, moisture, chemicals, ultraviolet
3.2.2 basicshearmodulus,n—theaverageshearmodulusof
light, and biological agents.
30 specimens fabricated and tested in accordance with 13.1.
3.2.3 basic shear strength, n—a near minimum value of the 3.2.15 safety factor, n—a reduction factor to account for
shear strength distribution determined as the one-sided lower uncertainty in establishing an allowable design stress.
D5574–94 (2005)
3.2.15.1 Discussion—The safety factor accounts for pos- 5.3 Modification factors can be applied to the allowable
sible differences between laboratory and end-use conditions, design stress by the design engineer as deemed appropriate for
differences in adhesive production lots, bonding variables, and
the expected service conditions of the adhesive, or in accor-
the assumption that there is no interaction between modifica-
dance with the requirements of a building code.
tion factors.
5.4 The allowable properties developed under these meth-
ods apply only to the actual adhesive formulation tested and
4. Summary of Test Methods
analyzed.
4.1 These test methods are based on a conservative estimate
5.5 Theallowablepropertiesdevelopedforagivenadhesive
of the near minimum value of the distribution of adhesive
shall apply only to adhesive bondlines with thicknesses in the
strengths measured by a standard test method. The basic
range for which data is available.
strength of the adhesive is the lower 5 % nonparametric
tolerance limit obtained by a sample of 59 specimens. The
6. Adhesive and Wood Preparation
allowabledesignstressisthebasicstrengthreducedbyasafety
factor as a minimum: 6.1 Obtain a representative sample from each lot of adhe-
sive to be tested.
allowable design stress 5 basic strength 3 safety factor
6.1.1 For liquid or paste adhesives, take a sample from each
The allowable shear modulus is the mean modulus of a
lot of at least 1 qt (446 mL).
group of specimens measured by a standard test method and
6.1.2 For adhesives consisting of more than one part, take a
adjusted by modification factors similar to those for strength as
required by the service environment. sufficient sample of each part to prepare at least 2 lb (908 g )
4.2 The allowable design stress (or modulus) can be modi- of adhesive at the time of test-specimen fabrication.
fied by one or more modification factors that are appropriate
6.1.3 For dry adhesives, take a sample from each lot
for the intended-service exposure of the adhesive.
weighing at least 1 kg (1.1 lb).
4.3 The modification factors used in these test methods are
6.2 Follow the adhesive manufacturer’s specifications for
durability, permanence, delamination, and creep.
proper packing, mixing, and handling of the sample.
4.3.1 Temperature and moisture are the principal variables
6.3 Follow the adhesive manufacturer’s instructions for
of both the durability and permanence factors. Chemicals, such
proper use of the adhesive. The information needed will vary
as preservatives or fire retardants, may constitute a third
for different types of adhesive. Important information may
element of the durability and permanence factors. These
include:
factors are shown in Appendix X1. Stress level and time, in
6.3.1 The acceptable moisture-content range for the wood.
addition to temperature and moisture, are important elements
of the creep favor. Chemicals may be important to the creep
6.3.2 Complete mixing directions for the adhesive.
factoriftheyplasticizeorotherwisesoftentheadhesive.Cyclic
6.3.3 The acceptable range of conditions for adhesive ap-
gradientsofmoistureandtemperatureareprincipalelementsof
plication, such as rate of spread, thickness of wet film, bead
the delamination factor.
size, number of coats to be applied, minimum temperature for
4.3.2 Modification factors are derived from standard test
application, single or double spread, and conditions for drying
methods and specimens under critical-use conditions such as
where more than one coat is required.
extreme temperature, moisture, chemical, or stress levels
6.3.4 The acceptable range of open- and closed-assembly
expected in service.
time over the ambient temperature and humidity range speci-
4.4 Flow charts showing tests and calculations required to
fied.
establish allowable shear stress, allowable tensile stress per-
pendicular to bond, and allowable shear modulus for a given 6.3.5 The acceptable range of curing conditions, including
adhesive are shown in Appendix X2. the pressure to be applied, if any; whether this pressure may be
provided by nails or staples, or both, or by other means; the
NOTE 1—The sequence described in the procedure
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