1、Designation: C794 15aC794 18Standard Test Method forAdhesion-in-Peel of Elastomeric Joint Sealants1This standard is issued under the fixed designation C794; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、 A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This test method covers a laboratory procedure
3、 for determining the strength and characteristics of the peel properties of acured-in-place elastomeric joint sealant, single- or multicomponent, for use in building construction.1.2 The values stated in metric (SI) units are to be regarded as the standard. The values given in parentheses are provid
4、ed forinformation only.1.3 The committee with jurisdiction over this standard is not aware of any comparable standards published by otherorganizations.1.4 This standard does not purport to address all of the safety problems,concerns, if any, associated with its use. It is theresponsibility of the us
5、er of this standard to establish appropriate safety safety, health, and healthenvironmental practices anddetermine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestabli
6、shed in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C717 Terminology of Building Seals and SealantsC1375 Guide for Su
7、bstrates Used in Testing Building Seals and SealantsE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method3. Terminology3.1 For the definitions used in this test method, see Terminolo
8、gy C717, standard conditions.4. Summary of Test Method4.1 This test method consists of preparing test specimens by embedding a wire mesh screen between two thin layers of thesealant being tested, on test substrates, curing these specimens under specified time and conditions, then placing the specime
9、n ina tension-testing machine in such a way that the embedded wire mesh screen is peeled back from the substrate at 180, whilemeasuring the force exerted as well as the mode of failure of the sealant from the substrate.5. Significance and Use5.1 There are differences in opinion among those concerned
10、 with sealant technology whether or not this adhesion-in-peel testsimulates the type of strain and e-tensile stresses encountered by a sealant in normal use. Nevertheless, this test provides a valuablemeasurement of the ability of the cured sealant to maintain a bond to the substrate under severe pe
11、el conditions.1 This test method is under the jurisdiction ofASTM Committee C24 on Building Seals and Sealants and is the direct responsibility of Subcommittee C24.30 on Adhesion.Current edition approved July 1, 2015Feb. 1, 2018. Published August 2015March 2018. Originally approved in 1975. Last pre
12、vious edition approved in 2015 asC794 15.C794 15a. DOI: 10.1520/C0794-15A.10.1520/C0794-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Sum
13、mary 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 been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommend
14、s 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 document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 Many sealant m
15、anufacturers utilize the adhesion-in-peel test for determining the adhesive characteristics of sealant/primercombinations with unusual or proprietary substrates. This test is especially useful for quality measurements comparing batches ofthe same sealant relative to adhesion or for studying adhesion
16、 of a given sealant to a variety of substrates.5.3 This test method alone is not appropriate for comparing the overall performance of different sealants in a given application.The adhesive force that determines if a given sealant is useful in a given application also depends on the modulus of elasti
17、city andthe degree to which the sealant will be strained. This test, as it exists, does not consider the modulus of elasticity, nor amount ofstress that will be produced by a given strain in an actual sealant in a moving joint. No known correlations are given to relate andapply modulus values to the
18、 peel values.5.4 This test requires that the results indicate whether the failure mode is primarily adhesive or cohesive. It is important to notethat a cohesive failure is not necessarily better than an adhesive failure, if the adhesive value is sufficient for the application. Havingadhesive failure
19、 allows one to study the change of adhesion with time and with the various stress conditions.6. Apparatus and Materials6.1 Tensile Testing Machine with tension grips capable of pulling at the rate of separation of approximately 50 mm (2 in.)/min,and having a chart indicator calibrated in 0.45-N (0.1
20、-lbf) units.6.2 Standard SubstratesThis test method may be performed on a wide variety of substrates. See Guide C1375 for a descriptionof standard substrates and recommended surface preparation. Since adhesive properties of a joint sealant are related to the natureof the substrate, it is strongly re
21、commended that whenever possible that adhesion-in-peel testing be performed on substrate samplesthat are representative of the building materials. Examples of such substrates include brick, marble, limestone, granite, aluminum,stainless steel, plastic, ceramic tile, and others.6.3 Masking Tape, pape
22、r, roll, 25 mm (1 in.) wide.6.4 Wire Mesh Screen, stainless steel or aluminum, 20-mesh, 0.4 mm (0.016 in.) wire thickness, cut to a width of 25 + 0, -2mm (1.0 + 0, -0.08 in.) by a minimum length of 250 mm (10 in.). The wire mesh screen selected must be flexible yet strong enoughto not tear during ad
23、hesion-in-peel testing. The wire mesh screen must be flat and free of kinks. To ensure adhesion of the jointsealant to the wire mesh, thoroughly clean the screen prior to use. Sealant primer on the wire mesh screen is generallyrecommended by the sealant manufacturer to enhance adhesion of the joint
24、sealant to the screen. Sealant may also be pre-appliedto the screen to enhance adhesion.6.4.1 DiscussionAdhesion of the joint sealant to the mesh screen is essential to evaluate adhesion-in-peel properties of thesealant to the substrate. Due to the unique characteristics of each sealant, the sealant
25、 manufacturer must determine for each sealantthe appropriate screen composition, mesh dimension, wire diameter and screen cleaning and priming procedure. Polyester mesh,fiberglass mesh, airplane cloth, fabric, plastic film or similar material can be used in lieu of a wire mesh provided that the mate
26、rialis pliable, of a thickness no greater than 0.5 mm (0.02 in.), does not adversely affect sealant cure and does not rupture duringadhesion-in-peel testing.6.5 Tooling Devicealuminum or similar rigid material, created to produce a 2 mm (0.08 in.) by 25 mm (1 in.) sealant beadand 4 mm (0.16 in.) by
27、25 mm (1 in.) sealant bead after tooling (Fig. 1). The width of the tooling device may be up to 27 mm(1.06 in.) to allow easy tooling of the sealant without snagging the edges of the screen.6.6 Putty Knife, rigid, approximately 40 mm (1.6 in.) wide.6.7 Knife, with sharp razor-type blade.7. Test Spec
28、imens and Cure Procedures7.1 Four test specimens (adhesion-in-peel samples) shall be prepared on each of the substrates using the following procedures:7.1.1 Condition a minimum of 250 g of sealant for 24 h at standard conditions. Multi-component sealants will require mixingfor 5 min or as recommende
29、d by the sealant manufacturer. Specific mixing equipment and mixing procedures may berecommended by the sealant manufacturer.7.1.2 Clean and prepare the substrate samples as described in Guide C1375. Substrate materials not described in C1375 shouldbe prepared in accordance with the sealant manufact
30、urers recommendations.7.1.3 Apply primer(s) to the substrate(s) if recommended by the sealant manufacturer.7.1.4 Masking tape can be applied to the substrate surfaces adjacent to the test area to allow easy removal of excess joint sealant.7.1.5 Wire mesh screens must be thoroughly cleaned and primed
31、, if required, as recommended by the sealant manufacturer.7.1.6 For each substrate preparation/cleaning condition to be tested, apply a bead of sealant at least 100 mm (4 in.) in lengthto the substrate surface (Fig. 2).7.1.7 Immediately place the wire mesh screen on the sealant bead and lightly tap
32、it into the joint sealant (Fig. 3).7.1.8 Holding the screen with a finger to prevent slippage, gently draw down the sealant imbedding the wire mesh into the wetsealant, using the special tooling device side A (Fig. 1) at an 90 angle to the substrate (Fig. 4). The wire mesh screen shouldbe imbedded t
33、o a uniform depth of 2 mm (0.08 in.) from the substrate surface (Fig. 5).7.1.9 Immediately apply a second bead of joint sealant over the first bead of sealant and wire mesh screen (Fig. 6).C794 1827.1.10 Again holding down the screen with a finger to prevent slippage, use the special tooling device
34、side B (Fig. 1) and drawdown the sealant at a 90 angle to the substrate. The total depth of the sealant should be 4 mm (0.16 in.) (Fig. 7) and the wire meshscreen should be imbedded uniformly at the approximate midpoint of the total sealant depth.7.1.11 Excess sealant beyond the edge of the wire mes
35、h screen may be removed while the sealant is wet using a putty knifeor spatula. Avoid moving the screen imbedded in the sealant. Masking tape, if used, should be removed at this time.7.1.12 After the sealant is cured, excess sealant may be carefully removed along the length of the test sample using
36、a razor knife.Fig. 8 shows a final prepared adhesion-in-peel test sample.7.1.13 Allow the sealant to cure as recommended by the sealant manufacturer. Standard curing time is 21 days at standardconditions. Curing time and conditions may vary depending on the sealant type and application.NOTE 1A 25 by
37、 2 mm (1 by 0.08 in.) indentationB 25 by 4 mm (1 by 0.16 in.) indentationFIG. 1 Special Tooling DeviceFIG. 2 First Sealant Bead Applied to Substrate (with masking tape)C794 183NOTE 1The producer may request conditions other than those specified in 7.1.13 for the curing period of single-component sea
38、lants provided theymeet the following requirements: (1) The curing period shall extend for 21 days; and (2) The temperature during the curing period shall not exceed 122F(50C).8. Test Procedure8.1 Once the sealant is fully cured, gently wrap the loose end of the wire mesh screen and bend back. Using
39、 a razor knife,provide a fresh cut along the sealant to the substrate interface (Fig. 9).8.1.1 Place the test specimen in the tensile testing machine with the substrate secured to the fixed member and the loose endof the wire mesh screen secured to the movable member at an angle of 180 (Fig. 10).8.1
40、.2 Pull the screen at a rate of 50 mm (2 in.)/min for a total of 1 min (Fig. 11).8.1.2.1 If the screen breaks during the testing, disregard the value. If possible, undercut the sealant with a razor knife and repeatthe test. If the screen continues to break, prepare new test samples using a higher st
41、rength wire mesh screen.8.1.2.2 If the sealant peels away cleanly from the screen, disregard the value. Undercut the sealant with the razor knife andrepeat the test. If adhesive failure to the screen continues, prepare new test samples using a more thoroughly cleaned or primed,or both, wire mesh scr
42、een. If necessary, use a material other than a wire mesh screen.8.1.2.3 If the adhesion-in-peel test sample shows adhesive failure to the screen in two repeated attempts but peel force valuesare above the specified requirements, further sample testing may not be required. In such cases, report failu
43、re mode as screendelamination, since adhesive or cohesive failure of the sealant to the substrate is not fully established. The screen should be pulledfor a total of 1 min as described in 8.1.2.FIG. 3 Wire Mesh Screen being Imbedded in Wet Sealant BeadFIG. 4 Tooling Sealant after Imbedding Wire Scre
44、en Mesh with Special Tooling Device Side AC794 184NOTE 2DiscussionSome sealants may have a non-homogeneous mode of failure during the initial adhesion-in-peel testing. During the first 30 to60 s of testing, the sealant may achieve a steady state and longer test duration may be needed to accurately a
45、ssess the failure mode of the sealant.8.1.3 Record the average peel force in Newton (pound-force) over the duration of the test.8.1.4 Record the peak force in Newton (pound force).8.1.5 Observe and record the approximate percentages of sealant failure modes over the total test area. Sealant failure
46、isdescribed as either adhesive or cohesive failure. See Fig. 12 for an example of each failure mode. Failure observed within thesubstrate (that is, paint removal, etc.) should be reported as substrate failure.8.2 Water Immersion TestUsing either four separate test specimens or the same test specimen
47、 used for dry adhesion testingand following completion of standard cure as described in 7.1.12, immerse the test samples for 7 days in distilled water conditionedto 23 6 2C (73 6 4F). Mortar and concrete specimen should be placed in a separate container from glass and aluminumspecimen because the hi
48、gh alkali condition generated could have an adverse effect on the glass and aluminum.8.2.1 Following water immersion, remove the test samples, lightly dry with a cloth or paper towel and test within 10 min asdescribed in 8.1 through 8.1.5.8.3 Additional conditions may be used including different cur
49、e conditions, different water temperature or duration of immersion,exposure of sealant to chemicals or other materials or exposure to ultraviolet radiation, heat or weathering.FIG. 5 Adhesion-in-Peel Test Specimen after Imbedding Wire Mesh ScreenFIG. 6 Applying Second Bead of SealantC794 1859. Report9.1 Report the following information for each sample tested:9.1.1 Description of substrate test sample, that is, bronze anodized aluminum, clear float glass, polished granite, etc.9.1.2 Description of substrate surface preparation and cleaning,9.1.3 D
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