1、Designation: C1681 09C1681 14Standard Test Method forEvaluating the Tear Resistance of a Sealant Under ConstantStrain1This standard is issued under the fixed designation C1681; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye
2、ar 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 This test method evaluates the impact of an induced tear on a sealant specimen that is dimensioned, cured accord
3、ing to theguidelines in Test Method C719 and then subjected to a constant strain. It is effective in differentiating between sealants that areused in dynamic joints subject to abrasion, punctures, tears, or combination thereof.1.2 Since this test method is for the evaluation of tear propagation, an
4、adhesive failure to the substrates provides no usable dataregarding tear propagation. This would be considered a failed test and that data would be discarded, or at least separated from theother data from specimens that did not experience an adhesive failure.1.3 This standard does not purport to add
5、ress all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.1.4 The committee with jurisdiction over this standard is
6、not aware of any comparable standards published by otherorganizations.2. Referenced Documents2.1 ASTM Standards:2C717 Terminology of Building Seals and SealantsC719 Test Method for Adhesion and Cohesion of Elastomeric Joint Sealants Under Cyclic Movement (Hockman Cycle)3. Terminology3.1 Definitions:
7、3.1.1 casting spacersrigid spacers made of an anti-adherent material used in the fabrication of joints to maintain the jointdimension during the extrusion, tooling and curing of the sealant material.3.1.2 separatorsrigid spacers used to maintain a constant strain on the joint specimens during the te
8、sting period whilemaintaining parallel bond surfaces.3.1 DefinitionsRefer to Terminology C717 for definitions of the following terms used in this test method: casting spacer.3.2 separatorsrigid spacers used to maintain a constant strain on the joint specimens during the testing period whilemaintaini
9、ng parallel bond surfaces.4. Summary of Test Method4.1 Test specimens are fabricated and cured in accordance with Test Method C719. At the end of the 21-day cure period, aninduced tear is created in the specimens by making a cut with a sharp blade in the midpoint of the joint. The specimens are then
10、extended to a specified strain at both standard conditions and at 26 6 2C (15 6 3F). Propagation of the induced tear ismeasured at 0, 24 and 168 h.1 This test method is under the jurisdiction of ASTM Committee C24 on Building Seals and Sealants and is the direct responsibility of Subcommittee C24.20
11、 on GeneralTest Methods.Current edition approved Jan. 1, 2009June 1, 2014. Published February 2009July 2014. Originally approved in 2009. Last previous edition approved in 2009 as C1681-09.DOI: 10.1520/C1681-09.10.1520/C1681-14.2 For referencedASTM standards, visit theASTM website, www.astm.org, or
12、contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have
13、 been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official docu
14、ment.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Significance and Use5.1 This test method is intended to determine if a joint that is subjected to a mechanically induced cut will resist tear propagationduring normal joint movem
15、ent.Asealant with a high resistance to tear propagation will typically perform better than a sealant witha low resistance to tear propagation.6. Apparatus6.1 A device capable of extending the test specimens to the specified strain.6.2 Freezer, to maintain a constant temperature of 26C.26C 6 2C.6.3 A
16、 suitable measuring device such as calipers able to measure the induced tears to 0.01 mm.6.4 #17 Knife Blade, 9 mm (38 in.) wide.7. Reagents and Materials7.1 Spatulas, for use in applying the sealant.7.2 Caulking Gun, for extruding sealant from cartridges when applicable.7.3 Glass Substratestwelve s
17、ubstrates, with minimum dimensions of 25 by 75 mm (1 by 3 in.) of the same finish are requiredfor each test specimen. product to be tested. Glass is the default substrate, however as mentioned in the scope, this is not anadhesion test, therefore the sealant must exhibit excellent adhesion to the sub
18、strate. Other rigid substrates in the above noteddimension are indeed acceptable.acceptable. Substrate blocks or plates should be of adequate thickness or reinforced such that theydo not flex or break during the testing.7.4 Casting SpacersMade from polytetrafluoroethylene (PTFE) or a suitable rigid
19、material shall be used with each testspecimen to which the test sealant will not bond and will provide the appropriate joint dimensions and configurations. Thesespacers are machined to provide exact The spacers provide joint dimensions of 12.7 by 12.7 by 50.8 mm (12 by 12 by 2 in.). SeeFig. 5 in Tes
20、t Method C719.7.5 Separators, to provide a constant strain on the specimen while maintaining parallel bond surfaces.7.6 Substrate Cleaning Material.7.7 Primer, if required on the substrates.7.8 A suitable measuring device, such as calipers, capable of measuring the induced cut in the sealant and add
21、itional changesin the cut to 0.01 mm.7.9 Marker, to identify the exact placement of the induced cut.7.10 A device which holds a #17 knife blade 9 mm (38 in.) wide to induce the cut into the test specimens. See Fig. 1.8. Conditioning8.1 Multicomponent SealantsPrepare six test specimens for each type
22、of substrate that is to be used in the test. Aftermaintaining the unopened sample for at least 24 h at standard conditions, mix thoroughly for 5 min at least 250 g of base compoundFIG. 1 #17 BladeC1681 142with the appropriate amount of curing agent. Extrude the sealant 12.7 by 12.7 by 50.8 mm (12 by
23、 12 by 2 in.) between parallel25.4 by 76.2 mm (1 by 3 in.) facessurfaces of similar blocks or plates. plates of the selected substrate. Use appropriate castingspacer blocks to form the proper size of the bead. Apply polyethylene adhesive tape or any other suitable inert release agent tothe inside su
24、rfaces of the spacers to prevent adhesion of the spacers to the sealant after cure. Use adhesive tape, rubber bands, orclamps to hold the test assembly together before and after filling it with the compound. In the case of a pourable-type compound,use masking or any other suitable tape to retain the
25、 compound.8.2 Clean the test substrates using the methods suggested in Test Method C719. Fabricate the joints using the casting spacers.Mask off the top of the substrate edges, extrude the test sealant into the cavity taking care to fill in the all of the corners, tool thetop surface flat, and remov
26、e the masking tape.8.3 Single-Component SealantsPrepare six test specimens as described in 8.1 except that no mixing of components isrequired. Condition the sealed cartridge or bulk container at standard conditions at least 24 h before use.8.4 Cure specimens made with multicomponent sealants for 14
27、days at standard conditions. During the second week of thecuring period, free the compound from the spacer blocks at the ends and bottom without damaging the sealant bead.8.5 Cure specimens made with single-component sealants for a total of 21 days at standard conditions. See 8.6.1.8.6 Separate the
28、casting spacers from the sealant as soon as practical during the curing period without damaging the sealant.Fourteen days is typically necessary.8.6.1 The producer may request conditions other than those specified in 8.5 for the curing period of single-component sealantsprovided they meet the follow
29、ing requirements: (1) The curing period shall extend for 21 days; and (2) The temperature duringthe curing period shall not exceed 50C (122F).9. Procedure9.1 Within 8 h after the cure period (14 days for multicomponent or 21 days for single component products), mark the exactlocation for the induced
30、 cut with a permanent marker and then induce a cut, 9 mm (38 in.) in length, and 12.7 mm (12 in.) deepwith the #17 knife blade. See Fig. 2. Make the cut as parallel as possible to the long direction of the sample, located directly onthe midpoint and go perpendicularly through thickness of the sealan
31、t.9.2 Extend all specimens until the separation between the substrates provides the desired/specified extension (in the absence ofa specified strain, the sealant shall be strained to its Test Method C719 movement capability). Apply this strain at a minimum rateof 3 mm per hour (18 in. per hour). See
32、 Appendix X2.9.3 When the specimens have reached their specified extension, block the specimens with the appropriate separator and removefrom the extension device/machine. Do not remove separators for the duration of test.9.4 Measure and record the length and width of the induced cut, immediately af
33、ter the joints have been blocked at the specifiedstrain. This is the 0 hour data.9.5 Place three specimens in the freezer at 26 6 2C.9.6 Place three specimens at room temperature laboratory conditions.9.7 After 24 and 168 h, measure and record the length and width of the induced cut on the top of th
34、e joint and record theobserved character of the tearing on the X and Y axis as noted in Fig. 3 (i.e., clean versus jagged, direction of the tear propagation,propagation of the tear at one or both ends of the induced cut, etc.).10. Calculation or Interpretation of Results10.1 Report the change in len
35、gth and width of the induced cut on the top of the joint in the sealant for each specimen alongthe X and Y axis noted below to the nearest 0.1 mm.10.2 Report the average change in dimension for length and width for the room temperature and 26C conditions at 24 and168 h.10.2.1 (L1 + L2 + L3)/3 = Aver
36、age change in Length.FIG. 2 Top View of Joint Showing the Placement of the Induced CutC1681 14310.2.1.1 L24 h L0h = L24 h= Change in Length at 24 h.10.2.1.2 L168 h L0h = L168 h = Change in Length at 168 h.10.2.2 (W1 + W2 + W3)/3 = Average change in Width.10.2.2.1 W24 h W0h = W24 h = Change in Width
37、at 24 h.10.2.2.2 W168 h W0h = W168 h = Change in Width at 168 h.10.3 See Table 1 for a suggested table for taking data.11. Report11.1 Report the following information:11.1.1 Sealant used, color, manufacturers lot, type (single component or multicomponent) and rated movement capability perTest Method
38、 C719 as designated by the manufacturer,11.1.2 Actual dimensions of the joint and configuration,11.1.3 Cleaning method for each substrate,11.1.4 Description of the test substrate(s),11.1.5 Primer used on specific substrates,11.1.6 Curing method and duration,11.1.7 Time of removal of casting spacers,
39、11.1.8 Movement induced on the sealant during the test in % of original joint width,11.1.9 Method used to elongate the specimens to the desired strain and an estimated strain rate,11.1.10 Length and width of induced cut in each specimen after 0, 24, and 168 h for the room temperature and cold temper
40、aturesand observations reported,11.1.11 Average change in length and width of the induced cut after 24 and 168 h at both the room temperature and 26Cconditioning, and11.1.12 Any other observations worthy of reporting.Top view of joint showing induced cut centered at the midpoint of the joint.NOTE 1M
41、easurements of the length of the cut (X axis) and width of cut (Y axis) are taken and reported at 0, 24, and 168 h.FIG. 3 Top View of a Joint that is Held Under a Fixed ExtensionTABLE 1 Suggested Table for Taking DataLength0 hWidth0 hLength24 hWidth24 hLength168 hWidth168 hSpecimen 1 RTSpecimen 2 RT
42、Specimen 3 RTAverage Change RTafter 24 and 168 hNA NASpecimen 1 26CSpecimen 2 26CSpecimen 3 26CAverage Change 26Cafter 24 and 168 hNA NAC1681 14412. Precision and Bias12.1 A preliminary study was conducted with 7 laboratories and 3 different sealants. Problems encountered in measurementresulted in r
43、evisions to the standard. Only single sets of tests were run so repeatability also was not able to be determined. Asummary of the program is included in the Appendix.12.2 An interlaboratory program will be conducted after the test method is approved and in practice.13. Keywords13.1 constant strain t
44、esting; fixed extension; movement induced tear; sealantAPPENDIXES(Nonmandatory Information)X1. PILOT STUDYX1.1 Apilot study was conducted on the performance of the initial draft of the proposed standard. Seven laboratories participatedby testing three different materials. Three samples of each mater
45、ial were to be prepared by each laboratory and stored at twodifferent temperatures during the test procedure.X1.2 The draft standard did not define the type and resolution of measurement devices. Some laboratories measured to the nearestmm while others provided readings to either 0.1 or 0.01 mm. The
46、se later data sets showed variation in all sample sets while thosemeasured to the nearest mm (or half mm) showed virtually no differences in the samples tested to make up the test results.X1.3 Since the standard has been revised to require greater resolution in taking all observations, Table X1.1 on
47、ly shows resultsfrom the laboratories that conducted more detailed tests. All readings are in millimeters and are the average of three samples.X1.4 The silicone and the urethane materials tested had a claimed movement capability rating of 25 %. The modified polyetherhad a claimed movement rating of
48、+10050 %. This is reflected in the initial width of cut noted in Table X1.1.C1681 145TABLE X1.1 Results from Four LaboratoriesNOTE 1All measurements are in mm.Material LabInitialLengthof CutChange in Length1 DayChange in Length7 DayInitial Widthof CutChange in Width1 DayChange in Width7 DaySilicone
49、RT A 7.03 13.20 27.18 3.73 0.18 0.36B 10.95 4.27 13.00 3.55 0.35 0.86C 9.63 6.50 18.27 2.90 0.10D 8.47 1.28 5.27 2.96 0.19 0.08Urethane RT A 7.62 0.76 0.58 3.66 0.33 0.08B 10.45 0.45 0.37 3.93 0.09 0.23C 8.30 0.33 0.07 2.87 0.17D 8.68 0.02 0.51 2.90 0.36 0.23Modified Polyether RT A 7.90 0.99 2.12 10.84 3.02 2.16B 11.27 0.38 0.08 13.34 0.09 0.07C 10.67 0.37 0.27 13.47 0.17D 9.98 0.86 0.76 12.17 0.47 0.20Silicone 29C A 6.63 5.97 6.67 3.50 1.68 1.13B 9.94 0.49 8.23 4.18 0.01 0.54C 9.07 0.77 0.33 3.47
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