1、Designation: D 3931 93a (Reapproved 2005)Standard Test Method forDetermining Strength of Gap-Filling Adhesive Bonds inShear by Compression Loading1This standard is issued under the fixed designation D 3931; the number immediately following the designation indicates the year oforiginal adoption or, i
2、n the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of compara-tive shear properties of gap
3、-filling adhesives in wood-to-woodjoints at specified thicknesses of bondline in the dry condition,when tested on standard specimens under specified conditionsof preparation, conditioning, and loading in compression. Thistest method is intended as an evaluation of gap-filling adhe-sives such as thos
4、e used to bond plywood to lumber, lumber tolumber, and other similar materials in building constructions.1.2 This test method also may be used to determine shearproperties of gap-filling adhesives in species of wood and inthicknesses of bondline other than those specified for thecomparative tests of
5、 shear properties within this test method.All procedures specified herein are applicable, excepting re-quirements for wood species and specific gravity, and thick-nesses of bondlines.1.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathemat
6、icalconversions to SI units that are provided for information onlyand are not considered standard.1.4 This 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
7、 practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 143 Test Methods for Small Clear Specimens of TimberD 905 Test Method for Strength Properties of AdhesiveBonds in Shear by Compression LoadingD 1151 Test Method for Effect
8、of Moisture and Temperatureon Adhesive BondsE 171 Specification for Standard Atmospheres for Condi-tioning and Testing Materials3. Terminology3.1 Definitions:3.1.1 gap-filling adhesive, nan adhesive capable of form-ing and maintaining a bond between surfaces that are notclose-fitting.3.1.1.1 Discuss
9、ionClose-fitting is relative to a given ma-terial and industry; for example, standards in constructiondiffer from standards in electronics. Some adhesives will bondby bridging without completely filling the gap; others by fillingthe gap completely.4. Significance and Use4.1 Structural design based o
10、n strength-of-materials prin-ciples requires knowledge of the mechanical properties of thestructural components, including adhesives. By nature of theiruse, the most important property of adhesive is shear strength.4.2 Shear strength measured by this test method is suitablefor use in adhesive develo
11、pment, manufacturing quality con-trol, and in materials performance specifications, as well asstructural design.5. Apparatus5.1 Testing Machine, having a capacity of about 15 000 lb(6818 kg) in compression or of sufficient capacity to test theadhesive in use. The machine shall be fitted with a shear
12、ingtool containing a self-aligning seat to ensure uniform lateraldistribution of the load. The machine shall be capable ofmaintaining a uniform rate of loading such that the load may beapplied with a continuous motion of the movable head tomaximum load at a rate of 9.20 in. (5.0 mm)/min with apermis
13、sible variation of 625 %. The shearing tool shown inFig. 1 of Test Method D 905 has been found satisfactory.Locate the testing machine in an atmosphere such that the1This test method is under the jurisdiction of ASTM Committee D14 onAdhesives and is the direct responsibility of Subcommittee D14.70 o
14、n ConstructionAdhesives.Current edition approved April 1, 2005. Published April 2005. Originallyapproved in 1980. Last previous edition approved in 1999 as D 393193a (1999)e 1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. Fo
15、r Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.moisture content of the specimens, developed under the con-ditions pre
16、scribed in 7.3, is not noticeably altered duringtesting.6. Test Specimen and Sample6.1 Test specimens for adhesive bonds shall conform to theform and dimensions shown in Fig. 1. Prepare bonded assem-blies as described in 7.1. Prepare test specimens for testing asdescribed in 7.2.6.2 Determine mean s
17、hear strengths of bonds at bondlinethicknesses of 0.006 and 0.060 in. (0.15 and 1.52 mm). Testsfor strengths of bonds at other thicknesses, in addition to thosespecified, shall be optional upon agreement between themanufacturer and the user.6.3 Test a minimum of 28 specimens, representing sevendiffe
18、rent bonded assemblies, to determine mean shear strengthsof bonds at each bondline thickness.7. Procedure7.1 Preparation of Bonded Assemblies:7.1.1 Prepare bonded assemblies with hard maple blocks(Acer saccharum or Acer nigrum) conditioned as described in7.3. The blocks shall have a minimum specific
19、 gravity of 0.65,based on ovendry weight and ovendry volume (Note 1).NOTE 1A method for selecting maple blocks of satisfactory specificgravity is described in the Appendix of Test Method D 905. For referencetests, the specific gravity of blocks may be determined in accordance withthe Weight and Mois
20、ture Content Section under Nail Withdrawal of TestMethods D 143.7.1.1.1 These blocks shall be straight-grained and free ofdefects, including knots, splits, birdseye, short grain, decay,and any unusual discoloration within the shearing area. Theblocks shall be of suitable size so that four test speci
21、mens canbe cut from one test joint, as shown in Fig. 2. Blocksapproximately34 by 212 by 14 in. (19 by 63 by 356 mm) havebeen found to be satisfactory for this purpose. The moisturecontent shall be from 8 to 10 % (conditions prescribed in 7.3.1)based on ovendry weight as determined on representatives
22、amples in accordance with the final measurement sectionunder radial and tangential shrinkage and the weighing sectionunder moisture determination in Test Methods D 143. Surfacethe blocks just prior to gluing, preferably with a hand-feedjointer. Make sure the surfaces remain unsanded and free fromdir
23、t.7.1.2 Use spacer strips to control bondlines to specifiedthicknesses between blocks. Spacers shall be wood veneer orplastic, and measure approximately12 by 312 in. (13 by 89mm) long. Place spacers crosswise at the ends and center of thelower test joint block. Apply adhesive in sufficient quantity
24、toensure squeezeout at the ends of the joint when blocks areunder pressure (Note 2).NOTE 2If the adhesive is to be applied as an extruded bead, the beadshould be38 to12 in. (10 to 13 mm) in diameter to ensure squeezeout inbondline thicknesses near 0.060 in. (1.5 mm). Use a smaller diameter beadof ad
25、hesive for thinner bondlines.7.1.2.1 Take care to avoid air entrapment in the bondline.Do not spread the adhesive closer than12 in. (13 mm) to anyspacer because adhesive may be entrapped between block andspacer, thereby increasing bondline thickness. Assemble theblocks immediately, unless specified
26、otherwise by agreementbetween the manufacturer and user of the adhesive. Apply a15-lb (7.0-kg) load uniformly over the entire bond area toensure firm contact between spacers and blocks of the assem-bly. Maintain the pressure on test joints at the conditionsprescribed in 7.1.7.1.3 Curing time for bon
27、ded assemblies shall be as speci-fied by the manufacturer of the adhesive, or else 30 days in thestandard atmosphere (7.3.1).7.2 Preparation of Test Specimens:TABLE 1Metric Equivalentsin.mm0.0641.63146.353419.0513444.45250.80FIG. 1 Form and Dimensions of Test SpecimenD 3931 93a (2005)27.2.1 Joint on
28、e edge of each bonded assembly to use as areference surface in further cutting. Rip-saw the other edge toreduce the width of the assembly to 2 in. (51 mm). Cut 2-in.long specimen blanks with the reference surface of the bondedassembly against the crosscut guide of the saw (Cut A, Fig. 2).Then using
29、a stop clamped to the crosscut guide, notch eachend of the specimen blank to achieve the 134-in. (44.5-mm)bond length (Cuts B1 and B2, Fig. 2). Always make the cutwith the reference surface against the crosscut guide. Make CutB1 extend through the laminate to the glueline. Make Cut B2extend through
30、the laminate and through the glueline. Thepurpose of the latter procedure is to ensure that the adhesive-adhered bond under test is aligned with the shear plane. Makethe final cuts (Cut C, Fig. 2) with the block vertical in order toremove waste and complete the steps on either end of thespecimen. Ke
31、ep the reference surface against the crosscutguide. Take special care in making all of the above cuts toensure that the loading surfaces are smooth, parallel to eachother, and perpendicular to the edges and the bondline.7.2.2 Measure and record the bond width and length to thenearest 0.010 in. (0.25
32、 mm).7.3 Conditioning:7.3.1 Use the standard atmosphere for adhesives for condi-tioning wood blocks prior to bonding, curing of test joints, andstoring of test joints and specimens prior to testing, unlessotherwise specified. The standard atmosphere (SpecificationE 171) is a relative humidity of 50
33、6 5 % and a temperature of73.4 6 3.6F (236 2C). Store wood blocks, test joints, andspecimens at these conditions for a period of 7 days, or untilthey reach equilibrium moisture content as indicated by noprogressive changes in weight.7.3.2 Other conditions such as described in Test MethodD 1151 in ma
34、terials performance specifications, or by mutualagreement between the parties of the test, may be used inaddition to the standard atmosphere.7.4 TestingPlace the test specimen in the shearing tool sothat the load may be applied as described in 5.1. The positionof the specimen with respect to the loa
35、ding ledge and self-adjusting bearing is shown in Fig. 3. Take special care toensure that the maple block rests on the lower ledge bearingand abuts the gap-filling bondline. The upper self-adjustingbearing should rest on the opposite maple block and gap-fillingbondline. Apply the loading with a cont
36、inuous motion of themovable crosshead at a rate of 0.20 in./min (5.0 mm/min) tofailure as described in 5.1.8. Calculation8.1 Calculate the nominal shear stress at failure in pounds-force per square inch (or pascals), and estimate the percentageof wood failure based on the measured bondline area betw
37、eenthe two laminations. Record for each specimen.8.2 Calculate the mean of the specimens of each grouptested as:xi5 (xi/n (1)where:xi= mean shear strength,TABLE 2Metric Equivalentsin.mm11238.1250.821263.514356.0FIG. 2 Bonded Assembly Showing Method of Cutting Four Test Specimen BlanksFIG. 3 Side Vie
38、w of Test Specimen Showing Method of NotchingSpecimen to Ensure Proper Alignment of Shearing Tool andPlane of ShearD 3931 93a (2005)3xi= individual shear strengths of specimens in a group,andn = number of specimens in the group.8.3 Calculate the standard deviation of the group as:s 5 =( xi22 ( xi!2/
39、n/n 2 1! (2)8.4 Calculate the standard error of the mean as:sx5 =s2/n (3)8.5 Calculate the mean percentage of wood failure, asshown in 8.2.9. Report9.1 Report the following information:9.1.1 Complete identification of the adhesive tested, includ-ing type, source, manufacturers code numbers, form, et
40、c.9.1.2 Type of adherends in test specimens; that is, species,specific gravity, and grain orientation (that is, edge or flatgrain).9.1.3 Bondline thicknesses tested, as determined from thick-nesses of spacers used rather than measured thickness of curedbondline.9.1.4 Moisture content of wood at time
41、 of bonding, methodof adhesive application, and time of cure.9.1.5 Temperature and relative humidity used for precondi-tioning wood blocks, curing of adhesive, and testing ofspecimens.9.1.6 Number of specimens tested at each bondline thick-ness.9.1.7 Number of test joints represented at each bondlin
42、ethickness.9.1.8 The mean, maximum, and minimum shear stresses atfailure, and mean percentage of wood failure for each bondlinethickness. Also report the standard deviation of test values forshear stress at failure. Individual test values may be included inthe report at the option of either manufact
43、urer or user.10. Precision and Bias10.1 Precision:10.1.1 At the present time there is no basis for a statementof precision concerning the reproducibility of results amonglaboratories. Such information may be available in the futurefollowing round-robin testing among laboratories.10.1.2 The precision
44、 of the test is a function of the proper-ties of the cured bondline; and if wood failure occurs, it is afunction of the woods variability. Precision shall be reportedin terms of the standard deviation of the data and the standarderror of the mean.10.2 BiasThe ability of this test method to measure t
45、hepure shear strength of the bond has not been established. Thetest is similar in principle to the method for the shear strengthof wood parallel to the grain described in the Shear Parallel toGrain portion of Test Methods D 143. The latter method hasbeen found to yield shear strength values close to
46、 the pureshear strength of wood due to offsetting factors of stressconcentrations in the specimen and friction in the shear tool.3For this reason the shear strengths of flexible adhesives that canrelieve stress concentrations may yield shear values somewhathigher than the pure shear strength when te
47、sted by this testmethod.11. Keywords11.1 adhesive; gap-filling; shear strengthASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the valid
48、ity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comme
49、nts are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States.
