Designation: D5574 − 94 (Reapproved 2012)Standard Test Methods forEstablishing Allowable Mechanical Properties of Wood-Bonding Adhesives for Design of Structural Joints1This standard is issued under the fixed designation D5574; the number immediately following the designation indicates the year oforiginal adoption 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 These test methods cover the principles for establishingallowable mechanical properties for adhesives that can be usedto design adhesive-bonded joints for structural components andassemblies of wood or wood with other materials. These testmethods are modeled after Practice D245.1.2 The properties determined are allowable shear stress,allowable tensile stress, and allowable shear modulus.1.3 In determination of allowable shear- and tensile-stresslevels, these test methods are limited by the horizontal shearand tension perpendicular-to-the-grain capacity of the woodadherends (hard maple, Acer saccharum, Marsh.). The adhe-sives so tested may actually have shear or tensile allowablestresses exceeding the wood, but the determined allowabledesign stress levels are limited (upper bounded) by the wood inthese test methods. If a wood other than hard maple is used fortesting the adhesive, then the allowable strengths are upperbounded by the properties of that particular wood.1.4 The strength properties are determined by standardASTM test methods. As a result, only procedural variationsfrom the standards and special directions for applying theresults are given in these test methods.1.5 Time-to-failure data derived from creep-rupture testing(see Test Method D4680) provide a measure of the ultimatestrength of an adhesive bond as a function of time at variouslevels of temperature and moisture.1.5.1 With proper caution, useful service life at a givenshear stress level may be extrapolated from relatively shortloading periods.1.6 The resistance of the adhesive to permanent loss ofproperties due to aging (permanence) is assessed by means ofstrength tests after constant elevated-temperature and moistureaging of test specimens.1.6.1 If the subject adhesives will be used to bond wood thathas been treated with a preservative, fire retardant, or any otherchemical to modify its properties, then the permanence of theadhesive shall be tested using wood adherends treated in thesame manner.1.7 Factors for durability, permanence, and creep derived byshear tests and analysis, are assumed to apply to tension(normal-to-the-bond) strength as well.1.8 Requirements for production, inspection, and certifica-tion of adhesives evaluated under these test methods are notincluded.1.9 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.2. Referenced Documents2.1 ASTM Standards:2D245 Practice for Establishing Structural Grades and Re-lated Allowable Properties for Visually Graded LumberD897 Test Method for Tensile Properties of Adhesive BondsD905 Test Method for Strength Properties of AdhesiveBonds in Shear by Compression LoadingD907 Terminology of AdhesivesD1101 Test Methods for Integrity of Adhesive Joints inStructural Laminated Wood Products for Exterior UseD1151 Practice for Effect of Moisture and Temperature onAdhesive BondsD2555 Practice for Establishing Clear Wood Strength ValuesD2559 Specification for Adhesives for Bonded StructuralWood Products for Use Under Exterior Exposure Condi-tionsD2915 Practice for Sampling and Data-Analysis for Struc-tural Wood and Wood-Based ProductsD3931 Test Method for Determining Strength of Gap-FillingAdhesive Bonds in Shear by Compression Loading1These test methods are under the jurisdiction of ASTM Committee D14 onAdhesives and are the direct responsibility of Subcommittee D14.70 on Construc-tion Adhesives.Current edition approved June 1, 2012. Published June 2012. Originallyapproved in 1994. Last previous edition approved in 2005 as D5574 – 94 (2005).DOI: 10.1520/D5574-94R12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at

[email protected] For Annual Book of ASTMStandards volume information, refer to the standard’s Document Summary page onthe ASTM website.Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D3983 Test Method for Measuring Strength and ShearModulus of Nonrigid Adhesives by the Thick-AdherendTensile-Lap SpecimenD4027 Test Method for Measuring Shear Properties ofStructural Adhesives by the Modified-Rail TestD4502 Test Method for Heat and Moisture Resistance ofWood-Adhesive JointsD4680 Test Method for Creep and Time to Failure ofAdhesives in Static Shear by Compression Loading(Wood-to-Wood)D4896 Guide for Use of Adhesive-Bonded Single Lap-JointSpecimen Test ResultsIEEE/ASTM SI 10 Standard for Use of the InternationalSystem of Units (SI): The Modern Metric System3. Terminology3.1 Definitions:3.1.1 allowable design stress, n—a stress to which a mate-rial can be subjected under stated service conditions with lowprobability of mechanical failure within the design lifetime.(D4896)3.1.1.1 Discussion—Allowable design stress is obtained bymultiplying the basic stress by a safety factor and possibly oneor more modification factors as required by the intendedservice environment.3.1.2 allowable shear stress, n—in an adhesive-bondedjoint, the allowable design stress for structural joints subjectedto shear force.3.1.3 allowable tensile stress, n—in an adhesive-bondedjoint, the allowable design stress for structural joints subjectedto tension force.3.1.4 creep rupture, n—the fracture of a material resultingfrom a sustained stress (or sum of stresses) above the creeprupture limit.3.1.4.1 Discussion—The material may experience creepthrough the primary, secondary, and tertiary stages of rupture.3.1.5 creep-rupture limit, n—the stress level below whichcreep rupture will not occur within a given time in a specifiedenvironment. See creep rupture.3.1.6 durability, n—as related to adhesive joints, the endur-ance of joint strength relative to the required service condi-tions. (D907)3.1.6.1 Discussion—Service conditions may include waterand other chemicals, temperature, stress, radiation,microorganisms, and other environmental factors.3.1.7 permanence, n—the resistance of an adhesive bond todeteriorating influences. (D907)3.1.8 structural adhesive, n—a bonding agent used fortransferring required loads between adherends exposed toservice environments typical for the structure involved. (D907)3.2 Definitions of Terms Specific to This Standard:3.2.1 allowable shear modulus, n—the modulus calculatedin accordance with Section 14, that is used for the design of astructural joint.3.2.2 basic shear modulus, n—the average shear modulus of30 specimens fabricated and tested in accordance with 13.1.3.2.3 basic shear strength, n—a near minimum value of theshear strength distribution determined as the one-sided lowerconfidence interval on the fifth percentile as determined inaccordance with 7.1. (See lower 5 % tolerance limit.)3.2.4 basic tensile strength, n—a near minimum value of thetensile strength distribution determined as the one-sided lowerconfidence interval on the fifth percentile as determined inaccordance with 9.1. (See lower 5 % tolerance limit.)3.2.5 creep factor, n—for modulus, the monotonic modulusas a function of loading rate expressed as the decimal fractionof the basic modulus.3.2.6 creep factor, n—for strength, the estimated 30 yearcreep rupture limit as a decimal fraction of the basic strength.3.2.7 delamination factor, n—a pass/fail factor based on thepercentage of delamination on the end grain of a laminate aftercyclic delamination treatment.3.2.7.1 Discussion—The factor is 0 or l: 0 if end-graindelamination is greater than 10 % of total end-grain bondline;1 if less than 10 % after cyclic soak-dry treatment.3.2.8 durability factor, n—the average strength under el-evated test conditions expressed as a decimal fraction of thestrength at standard condition.3.2.8.1 Discussion—Increases in temperature and moisturelevel usually lower strength temporarily, as long as the speci-men is not so weakened that fracture occurs. Decreases intemperature and moisture level usually increase strength.Exceptions occur when increasing the temperature raises thelevel of adhesive cure and strength, or decreasing the tempera-ture or moisture induces brittleness and stress concentrations.3.2.9 lower 5 % nonparametric tolerance limit [NTL],n—an estimate of the one-sided lower confidence bond on thefifth percentile of the strength distribution determined as thelowest ranked value (fast order statistic) of sample of speci-mens from a population.3.2.10 lower 5 % parametric tolerance limit [PTL], n—anestimate of the lower confidence bound on the fifth percentileof the strength distribution calculated as the mean of a sampleminus the sample standard deviation multiplied by a confi-dence level factor.3.2.11 lower 5 % tolerance limit, n— an estimate of theone-sided lower confidence bound on the fifth percentile of thestrength distribution of a population of specimens.3.2.12 modification factor, n—any external or internal factorof the service environment that temporarily or permanentlyalters the strength or stiffness of an adhesive.3.2.13 multiaxial stress, n—stress in two or three perpen-dicular directions, bi- or triaxial stress.3.2.13.1 Discussion—In most wood structures bonded withstructural adhesives, multiaxial stress consists of a shear stressin the plane of, and tension stress normal to the plane of theadhesive layer.3.2.14 permanence factor, n—the estimated residualstrength at 30 years expressed as a decimal fraction of theoriginal strength at standard conditions.3.2.14.1 Discussion—This factor accounts for permanent,D5574 − 94 (2012)2usually long-term, changes in strength or modulus due to theeffects of factors such as heat, moisture, chemicals, ultravioletlight, and biological agents.3.2.15 safety factor, n—a reduction factor to account foruncertainty in establishing an allowable design stress.3.2.15.1 Discussion—The safety factor accounts for pos-sible differences between laboratory and end-use conditions,differences in adhesive production lots, bonding variables, andthe assumption that there is no interaction between modifica-tion factors.4. Summary of Test Methods4.1 These test methods are based on a conservative estimateof the near minimum value of the distribution of adhesivestrengths measured by a standard test method. The basicstrength of the adhesive is the lower 5 % nonparametrictolerance limit obtained by a sample of 59 specimens. Theallowable design stress is the basic strength reduced by a safetyfactor as a minimum:allowable design stress 5 basic strength 3safety factorThe allowable shear modulus is the mean modulus of agroup of specimens measured by a standard test method andadjusted by modification factors similar to those for strength asrequired by the service environment.4.2 The allowable design stress (or modulus) can be modi-fied by one or more modification factors that are appropriatefor the intended-service exposure of the adhesive.4.3 The modification factors used in these test methods aredurability, permanence, delamination, and creep.4.3.1 Temperature and moisture are the principal variablesof both the durability and permanence factors. Chemicals, suchas preservatives or fire retardants, may constitute a thirdelement of the durability and permanence factors. Thesefactors are shown in Appendix X1. Stress level and time, inaddition to temperature and moisture, are important elementsof the creep favor. Chemicals may be important to the creepfactor if they plasticize or otherwise soften the adhesive. Cyclicgradients of moisture and temperature are principal elements ofthe delamination factor.4.3.2 Modification factors are derived from standard testmethods and specimens under critical-use conditions such asextreme temperature, moisture, chemical, or stress levelsexpected in service.4.4 Flow charts showing tests and calculations required toestablish allowable shear stress, allowable tensile stress per-pendicular to bond, and allowable shear modulus for a givenadhesive are shown in Appendix X2.NOTE 1—The sequence described in the procedure sections of these testmethods are not absolute. The delamination factor sets a pass/fail criteriafor a given adhesive for exterior wet-use applications. If there is any doubtthat the adhesive will pass the delamination requirement, the user canconduct this test before all others in order to save the expense ofconducting the other tests needlessly.5. Significance and Use5.1 Safe and reliable mechanical properties for adhesivesare necessary to achieve the full structural benefit of adhesivesin bonded structural components and assemblies.5.2 An adhesive’s properties exhibit a natural variation ordistribution of values. The allowable design stress for anadhesive must be adjusted to allow for variability and environ-mental effects to ensure human safety and prevent prematurefailure of costly structures.5.3 Modification factors can be applied to the allowabledesign stress by the design engineer as deemed appropriate forthe expected service conditions of the adhesive, or in accor-dance with the requirements of a building code.5.4 The allowable properties developed under these meth-ods apply only to the actual adhesive formulation tested andanalyzed.5.5 The allowable properties developed for a given adhesiveshall apply only to adhesive bondlines with thicknesses in therange for which data is available.6. Adhesive and Wood Preparation6.1 Obtain a representative sample from each lot of adhe-sive to be tested.6.1.1 For liquid or paste adhesives, take a sample from eachlot of at least 1 qt (446 mL).6.1.2 For adhesives consisting of more than one part, take asufficient sample of each part to prepare at least 2 lb (908 g) ofadhesive at the time of test-specimen fabrication.6.1.3 For dry adhesives, take a sample from each lotweighing at least 1 kg (1.1 lb).6.2 Follow the adhesive manufacturer’s specifications forproper packing, mixing, and handling of the sample.6.3 Follow the adhesive manufacturer’s instructions forproper use of the adhesive. The information needed will varyfor different types of adhesive. Important information mayinclude:6.3.1 The acceptable moisture-content range for the wood.6.3.2 Complete mixing directions for the adhesive.6.3.3 The acceptable range of conditions for adhesiveapplication, such as rate of spread, thickness of wet film, beadsize, number of coats to be applied, minimum temperature forapplication, single or double spread, and conditions for dryingwhere more than on