1、Designation: D 4688 99 (Reapproved 2005)Standard Test Method forEvaluating Structural Adhesives for Finger Jointing Lumber1This standard is issued under the fixed designation D 4688; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、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 is designed to evaluate adhesives forfinger jointing lumber used in the manufacture of s
3、tructuralglued laminated timber. It tests the tensile strength of jointsunder the following treatments; dry with no treatment, wetafter one vacuum-pressure soak treatment, and wet after cyclicboil-dry treatment.1.2 The values stated in SI units are to be regarded as thestandard. The values given in
4、parentheses are for informationonly.1.3 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 practices and determine the applica-bility of regulatory limi
5、tations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 907 Terminology of AdhesivesD 2559 Specification for Adhesives for Structural Lami-nated Wood Products for Use Under Exterior (Wet Use)Exposure Conditions3. Terminology3.1 DefinitionsMany terms in this test method are definedin Termin
6、ology D 907.3.2 Definitions of Terms Specific to This Standard:3.2.1 billet, na piece cut from a vertical finger jointassembly as an intermediate step in making specimens.3.2.2 finger joint assembly, na short portion of two boardsjoined at their ends by a finger joint obtained from a finger jointpro
7、duction line for testing, frequently referred to as an assem-bly.3.2.3 sample, na group of finger joint assemblies obtainedfrom a finger joint production line for statistical purposes.3.2.3.1 DiscussionIn the laminating industry the termsample is used for an individual finger joint assembly.3.2.4 sp
8、ecimen, nan individual strip,14 by 138 (approxi-mately) by 12 in. (6.4 by 35 by 305 mm), cut from a finger jointassembly for the tension test described in this test method.4. Significance and Use4.1 This test method is specifically designed to measure theperformance of adhesives in finger joints man
9、ufactured underproduction line conditions.4.2 The results of the test method may be used to certify anadhesive as suitable for finger jointing lumber underproduction-line conditions where the intended end use of thefinger jointed lumber will be in a structural glued laminatedtimber. When the test re
10、sults are to be used for certification ofan adhesive for this purpose, use a standard wood species anda standard finger profile. Standard species may be found inTable 1 of Specification D 2559. Two standard finger profilescommonly used in the manufacture of structural glued lami-nated timber industr
11、y are shown in Fig. 1.34.3 This test method is not intended for quality control asthe test assemblies are selected for their absence of defectsusually found in run-of-the-mill lumber and finger joints.5. Apparatus5.1 Test Machine, capable of applying a calibrated tensileforce up to 23 kN (5000 lbf),
12、 equipped with Templin (wedge-action) grips with grip area of 38 by 75 mm (112 by 3 in.).5.2 Vacuum Pressure Vessel, capable of drawing and hold-ing a vacuum of at least 635 mm (25 in.) of mercury (sea level)for 30 min, holding a pressure of 620 6 35 kPa (75 6 2 psi)for 30 min, and capacity to ensur
13、e that all of the specimens areat least 51 mm (2 in.) below the water level during thecomplete vacuum-pressure cycle.5.3 Tank for Boiling, capacity such that all specimens are atleast 51 mm (2 in.) below the water level for the duration of theboil cycles.5.4 Oven, capable of operating continuously f
14、or 20 h at 636 2C (145 6 5F) with sufficient air circulation to lower themoisture content of the group of specimens to 8 % within 20 h.5.4.1 Timer, to shut the oven off automatically is desirable.1This test method is under the jurisdiction of ASTM Committee D14 onAdhesives and is the direct responsi
15、bility of Subcommittee D14.30 on WoodAdhesives.Current edition approved April 1, 2005. Published April 2005. Originallyapproved in 1987. Last previous edition approved in 1999 as D 4688 99.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at servic
16、eastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3American Institute of Timber Construction, 7012 S. Revere Parkway, Suite 140,Englewood, CO 80112.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Co
17、nshohocken, PA 19428-2959, United States.6. Specimen Preparation6.1 Obtain a sample consisting of either 20 horizontal orvertical finger joint assemblies from a finger joint productionline. The boards must be nominal 2 by 4-in. or 2 by 6-in. Rejectany assembly with obvious defects in the lumber or j
18、oint.6.2 Horizontal Joint (Fig. 2(a):6.2.1 Joint one face of each assembly until the finger on thesurface is feathered as shown in Fig. 2(c).6.2.2 Joint one edge of the assembly for end cutting andripping at a later stage.6.2.3 Plane the second face of the assembly until the fingeron the surface is
19、feathered maintaining 35-mm (138-in.)assembly thickness or nearly so.NOTE 1It is more important to feather the finger than to maintain the35-mm (138-in.) thickness.6.2.4 Cut the assembly to a 305-mm (12-in.) length with thefinger jointed area at the center.6.2.5 Rip individual specimens 6.4-mm (14-i
20、n.) thick (Fig.1) from the assembly starting with the jointed edge of theassembly (see 6.2.2) against the saw guide. A thin hollow-ground rip saw blade is preferred but the important criteria isthe straightness of the cut. Check cut specimens for uniformthickness throughout. Thickness shall not vary
21、 by more than0.5 mm (0.02 in.). Number the specimens in order from oneside of the assembly to the other.6.3 Vertical Joint (Fig. 2(b):6.3.1 Joint one edge of the finger joint assembly.6.3.2 Joint one face of the finger joint assembly.6.3.3 With the jointed edge against the saw guide, rip billets40 m
22、m (1916 in.) wide from the assembly.NOTE 2The 40-mm (1916-in.) dimension is not critical but thisdimension must be enough to allow feathering the fingers in followingsteps.6.3.4 Joint and plane the sides of each billet so the exposedsides of the fingers are feathered as described in 6.2.1 and6.2.3.6
23、.3.5 Rip four individual specimens of 6.4-mm (14-in.)thickness from each billet of the assembly as in 6.2.5. Numberthe specimens in order from one side of the assembly to theother. Use the same order for each assembly.6.4 Inspect specimens for defects. Assemblies yieldingspecimens that have obvious
24、strength-reducing characteristicssuch as: low visual density, knots, steep slope of grain,compression wood, compression failures, decay, pitch pockets,or stress risers due to errors in specimen preparation, may berejected. If specimens with questionable strength characteris-tics are tested they shal
25、l be identified by appropriate notes onthe report form prior to exposure and testing.NOTE 1Recommended by American Institute of Timber Construc-tion.3FIG. 1 Standard Joint Profiles for Certification TestsFIG. 2 Finger Joint Assembly and Specimen DescriptionsD 4688 99 (2005)26.5 Condition all specime
26、ns to equilibrium moisture content(EMC) at 23 6 2C (73 6 4F) and 50 to 65 6 5 % relativehumidity. Monitor the weight periodically to determine whenequilibrium is reached.6.6 Weigh all specimens to the nearest 0.01 g and record theweight. Measure the width and thickness of the specimens tothe nearest
27、 0.25 mm (0.010 in.) and record the measurements.6.7 Randomly assign two specimens from each of the 20finger joint assemblies in the sample to each test (that is, dry,soak, and boil). (Note this requires only six specimens fromeach assembly, the other specimens are extra.) Fig. 3 shows thesource and
28、 distribution of the specimens.7. Procedure7.1 Dry Test (No Treatment):7.1.1 As described in 6.7, assign 40 specimens to this test.Test each specimen to failure by loading at a rate of 5 mm/min(0.20 in./min). Maintain a space of 210 6 6mm(66 0.25 in.)between the ends of the jaws of the grips. Record
29、 the load atfailure.NOTE 3Be very careful to align the specimen with the principal axisof the test grip. Failure to do this will increase the variability of the results.Markings or spacers on the grips, or some other device is recommendedto ensure proper front-to-rear alignment, and a plumb bob or o
30、ther deviceis recommended to ensure the vertical alignment.7.1.2 Determine the failure mode using the criteria given inAnnex A1 independent of any knowledge of the strength testresult.7.2 Cold Water Vacuum-Pressure Soak Test:7.2.1 As described in 6.7, assign 40 specimens to this test.Place all 40 sp
31、ecimens in a vacuum-pressure vessel withspacers between them so that water has free access to allsurfaces. Fill the vessel with tap water at 18.5 to 27.5C (65 to80F) so that all specimens are at least 51 mm (2 in.) below thesurface of the water. After filling, seal the vessel and draw avacuum of at
32、least 635 mm (25 in.) of mercury (sea level).Hold the vacuum for 30 min, then release the vacuum andapply pressure of 620 6 35 kPa (75 6 2 psi). Hold thispressure for 2 h, then release. Remove the specimens from thepressure vessel and place them submerged in water at roomtemperature until tested.7.2
33、.2 Wipe the surface of each specimen with a dry cottoncloth or paper towel and test wet as described in 7.1.1. Recordthe load at failure.7.2.3 After the specimens have dried, determine the failuremode as described in 7.1.2. Record the failure mode.NOTE 1Thus: 20 assemblies 3 2 specimens/assembly = 4
34、0 specimens/test.FIG. 3 Flowchart of the Source and Allocation of Individual Test SpecimensD 4688 99 (2005)37.3 Cyclic Boil Test:7.3.1 As described in 6.7, assign 40 specimens to this test.Place all 40 specimens in the boil tank with spacers so thatwater has free access to all surfaces. Fill with wa
35、ter such thatthe specimens are at least 51 mm (2 in.) below the water level.Boil specimens for 4 h, then dry them in an oven at 63 6 2C(145 6 5F) with sufficient air circulation to lower the moisturecontent to 8 % (ovendry basis) in no more than 20 h.NOTE 4The rate of air circulation, the size of th
36、e load of specimensin the oven, and the spacing of the specimens greatly affect drying timeand the steepness of the moisture gradient in the specimen. Variation ofthese factors strongly affects the repeatability of the test method. Ifrepeatability (within-laboratory variability) or reproducibility (
37、betweenlaboratories) is important, the drying variables must be maintained asconstant as possible from one series of tests to the next. If this is notpossible, the drying should be conducted so that the specimens reach 8 %moisture content within the same drying period in every test. One way todo thi
38、s is to monitor the weight of the specimens and adjust the oven ventsso the specimens reach the target 8 % moisture in 15 to 20 h. As an aid infollowing moisture content, the weight of specimens at 8 % moisturecontent is about 96 % of their weight at 12 % moisture content. The dryingtime required ca
39、n be established with some of the extra specimens cutfrom the 20 assemblies.7.3.2 Repeat the boil-dry cycle five more times; exceptduring the final cycle do not dry the specimens. Cool thespecimens to room temperature submerged in water and keepthem there until they are tested.7.3.3 Test wet in tens
40、ion as described in 7.2.2. Record theload at failure.7.3.4 After the specimens have dried, determine the failuremode as described in 7.1.2. Record the failure mode.NOTE 5Nonmandatory guidelines for joint performance follow:Mode 1 An unacceptable failure.Modes 2 and 3 Unconditionally acceptable failu
41、re.Modes 4, 5, and 6 Conditionally acceptable failure if strength is ac-ceptable.8. Calculation of Results8.1 Calculate the tensile stress at failure in megapascals(pounds-force per square inch) as the load at failure in newtons(pounds-force) divided by the cross-sectional area of thespecimen expres
42、sed to the nearest mm2(0.01 in.2).8.2 Estimate the 25th, 50th, and 75th percentiles for thegroup of specimens in the following manner:8.2.1 Arrange the specimens in order of increasing strength.8.2.2 Estimate the 25th percentile as the average of the 10thand 11th lowest strength values.8.2.3 Estimat
43、e the 50th percentile as the average of the 20thand 21st values.8.2.4 Estimate the 75th percentile as the average of the 30thand 31st strength values.8.3 Determine the upper and lower adjacent values (seedefinition below) for the group of specimens. Determine theoutliers (test values outside the ran
44、ge expressed by the upperand lower adjacent values).25th percentile = Q1 = the value below which 25 % of the observationsfall.50th percentile = Q2 = the value below which 50 % of the observationsfall.75th percentile = Q3 = the value below which 75 % of the observationsfall.Upper adjacent value = the
45、 largest observation equal to or less thanthe quantity Q3+1.5(Q3Q1).Lower adjacent value = the smallest observation greater than or equalto the quantity Q11.5(Q3Q1).Outliers = observations greater than the upper adjacentvalue or less than the lower adjacent value.8.4 Calculate the mean and standard
46、deviation. Specimensexhibiting failure mode 6 may be excluded from the calcula-tion. Include specimens with failure modes 1, 2, 3, 4, and 5 inthe calculation unless the strength value is an outlier or thewood is of poor quality (such as compression wood, etc.).9. Report9.1 Include the following gene
47、ral information in the report:9.1.1 Complete identification of the adhesive tested includ-ing type, source, manufacturers code numbers, form, and anyother pertinent information,9.1.2 Adhesive application and bonding conditions used toprepare the finger jointed boards,9.1.3 Conditioning procedure use
48、d before testing,9.1.4 Temperature and relative humidity of the test room,9.1.5 Number of finger joint assemblies represented in thetest, and9.1.6 Number of specimens per assembly tested in each test(dry, soaked, and boiled),9.2 Include the following statistical information in thereport:9.2.1 The ra
49、nge of test values,9.2.2 The 25th, 50th, and 75th percentile values,9.2.3 The upper and lower adjacent values,9.2.4 Outliers identified by finger joint assembly and speci-men number,9.2.5 Failure mode 6 specimens identified by finger jointassembly and specimen number,9.2.6 Specimens with defects of material or bonding discov-ered after testing identified by finger joint assembly andspecimen number,9.2.7 The mean and standard deviation, and9.2.8 The statistical mode (most frequent value) of theobserved failure modes.10. Precision and Bias10.
