1、Designation: C794 15aStandard 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. A numb
2、er 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 fordet
3、ermining the strength and characteristics of the peel prop-erties of a cured-in-place elastomeric joint sealant, single- ormulticomponent, for use in building construction.1.2 The values stated in metric (SI) units are to be regardedas the standard. The values given in parentheses are providedfor in
4、formation only.1.3 The committee with jurisdiction over this standard is notaware of any comparable standards published by other orga-nizations.1.4 This standard does not purport to address all of thesafety problems, if any, associated with its use. It is theresponsibility of the user of this standa
5、rd to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C717 Terminology of Building Seals and SealantsC1375 Guide for Substrates Used in Testing Building Sealsand SealantsE177 Practic
6、e for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 For the definitions used in this test method, see Termi-nology C717, standard conditions.4. Summary of Test Method4.1 This te
7、st method consists of preparing test specimens byembedding a wire mesh screen between two thin layers of thesealant being tested, on test substrates, curing these specimensunder specified time and conditions, then placing the specimenin a tension-testing machine in such a way that the embeddedwire m
8、esh screen is peeled back from the substrate at 180,while measuring the force exerted as well as the mode offailure of the sealant from the substrate.5. Significance and Use5.1 There are differences in opinion among those concernedwith sealant technology whether or not this adhesion-in-peeltest simu
9、lates the type of strain and e-tensile stresses encoun-tered by a sealant in normal use. Nevertheless, this testprovides a valuable measurement of the ability of the curedsealant to maintain a bond to the substrate under severe peelconditions.5.2 Many sealant manufacturers utilize the adhesion-in-pe
10、eltest for determining the adhesive characteristics of sealant/primer combinations with unusual or proprietary substrates.This test is especially useful for quality measurements com-paring batches of the same sealant relative to adhesion or forstudying adhesion of a given sealant to a variety of sub
11、strates.5.3 This test method alone is not appropriate for comparingthe overall performance of different sealants in a given appli-cation. The adhesive force that determines if a given sealant isuseful in a given application also depends on the modulus ofelasticity and the degree to which the sealant
12、 will be strained.This test, as it exists, does not consider the modulus ofelasticity, nor amount of stress that will be produced by a givenstrain in an actual sealant in a moving joint. No knowncorrelations are given to relate and apply modulus values to thepeel values.5.4 This test requires that t
13、he results indicate whether thefailure mode is primarily adhesive or cohesive. It is importantto note that a cohesive failure is not necessarily better than anadhesive failure, if the adhesive value is sufficient for theapplication. Having adhesive failure allows one to study thechange of adhesion w
14、ith time and with the various stressconditions.1This test method is under the jurisdiction ofASTM Committee C24 on BuildingSeals and Sealants and is the direct responsibility of Subcommittee C24.30 onAdhesion.Current edition approved July 1, 2015. Published August 2015. Originallyapproved in 1975. L
15、ast previous edition approved in 2015 as C794 15. DOI:10.1520/C0794-15A.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe AS
16、TM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16. Apparatus and Materials6.1 Tensile Testing Machine with tension grips capable ofpulling at the rate of separation of approximately 50 mm (2in.)/min, and having a chart indi
17、cator calibrated in 0.45-N(0.1-lbf) units.6.2 Standard SubstratesThis test method may be per-formed on a wide variety of substrates. See Guide C1375 for adescription of standard substrates and recommended surfacepreparation. Since adhesive properties of a joint sealant arerelated to the nature of th
18、e substrate, it is strongly recom-mended that whenever possible that adhesion-in-peel testing beperformed on substrate samples that are representative of thebuilding materials. Examples of such substrates include brick,marble, limestone, granite, aluminum, stainless steel, plastic,ceramic tile, and
19、others.6.3 Masking Tape, paper, roll, 25 mm (1 in.) wide.6.4 Wire Mesh Screen3stainless 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 (10in.). The wire mesh screen selected must be flexible yet strongen
20、ough to not tear during adhesion-in-peel testing. The wiremesh screen must be flat and free of kinks. To ensure adhesionof the joint sealant to the wire mesh, thoroughly clean thescreen prior to use. Sealant primer on the wire mesh screen isgenerally recommended by the sealant manufacturer to en-han
21、ce adhesion of the joint sealant to the screen. Sealant mayalso be pre-applied to the screen to enhance adhesion.6.4.1 DiscussionAdhesion of the joint sealant to the meshscreen is essential to evaluate adhesion-in-peel properties ofthe sealant to the substrate. Due to the unique characteristics ofea
22、ch sealant, the sealant manufacturer must determine for eachsealant the appropriate screen composition, mesh dimension,wire diameter and screen cleaning and priming procedure.Polyester mesh, fiberglass mesh, airplane cloth, fabric, plasticfilm or similar material can be used in lieu of a wire meshpr
23、ovided that the material is pliable, of a thickness no greaterthan 0.5 mm (0.02 in.), does not adversely affect sealant cureand does not rupture during adhesion-in-peel testing.6.5 Tooling Devicealuminum or similar rigid material,created to producea2mm(0.08 in.) by 25 mm (1 in.) sealantbead and 4 mm
24、 (0.16 in.) by 25 mm (1 in.) sealant bead aftertooling (Fig. 1). The width of the tooling device may be up to27 mm (1.06 in.) to allow easy tooling of the sealant withoutsnagging 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
25、.7. Test Specimens and Cure Procedures7.1 Four test specimens (adhesion-in-peel samples) shall beprepared on each of the substrates using the following proce-dures:7.1.1 Condition a minimum of 250 g of sealant for 24 h atstandard conditions. Multi-component sealants will requiremixing for 5 min or a
26、s recommended by the sealant manufac-turer. Specific mixing equipment and mixing procedures maybe recommended by the sealant manufacturer.7.1.2 Clean and prepare the substrate samples as describedin Guide C1375. Substrate materials not described in C1375should be prepared in accordance with the seal
27、ant manufactur-ers recommendations.7.1.3 Apply primer(s) to the substrate(s) if recommended bythe sealant manufacturer.7.1.4 Masking tape can be applied to the substrate surfacesadjacent to the test area to allow easy removal of excess jointsealant.7.1.5 Wire mesh screens must be thoroughly cleaned
28、andprimed, if required, as recommended by the sealant manufac-turer.7.1.6 For each substrate preparation/cleaning condition tobe tested, apply a bead of sealant at least 100 mm (4 in.) inlength to the substrate surface (Fig. 2).7.1.7 Immediately place the wire mesh screen on the sealantbead and ligh
29、tly tap 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 thewet sealant, using the special tooling device side A (Fig. 1)at an 90 angle to the substrate (Fig. 4). The wire mesh screenshould be imbe
30、dded to a uniform depth of 2 mm (0.08 in.) fromthe substrate surface (Fig. 5).7.1.9 Immediately apply a second bead of joint sealant overthe first bead of sealant and wire mesh screen (Fig. 6).7.1.10 Again holding down the screen with a finger toprevent slippage, use the special tooling device side
31、B (Fig.1) and draw down the sealant at a 90 angle to the substrate.3Available from Tetko Inc., 333 South Highland Ave., Briarcliff Manor, NY10510. Also available from McMaster Carr Supply Co., P.O. Box 4355, Chicago, IL60680.NOTE 1A 25 by 2 mm (1 by 0.08 in.) indentationB 25 by 4 mm (1 by 0.16 in.)
32、indentationFIG. 1 Special Tooling DeviceC794 15a2The total depth of the sealant should be 4 mm (0.16 in.) (Fig.7) and the wire mesh screen should be imbedded uniformly atthe approximate midpoint of the total sealant depth.7.1.11 Excess sealant beyond the edge of the wire meshscreen may be removed wh
33、ile the sealant is wet using a puttyknife or spatula. Avoid moving the screen imbedded in thesealant. Masking tape, if used, should be removed at this time.7.1.12 After the sealant is cured, excess sealant may becarefully removed along the length of the test sample using arazor knife. Fig. 8 shows a
34、 final prepared adhesion-in-peel testsample.7.1.13 Allow the sealant to cure as recommended by thesealant manufacturer. Standard curing time is 21 days atstandard conditions. Curing time and conditions may varydepending on the sealant type and application.FIG. 2 First Sealant Bead Applied to Substra
35、te (with maskingtape)FIG. 3 Wire Mesh Screen being Imbedded in Wet Sealant BeadFIG. 4 Tooling Sealant after Imbedding Wire Screen Mesh withSpecial Tooling Device Side AFIG. 5 Adhesion-in-Peel Test Specimen after Imbedding WireMesh ScreenC794 15a38. Test Procedure8.1 Once the sealant is fully cured,
36、gently wrap the looseend of the wire mesh screen and bend back. Using a razorknife, provide a fresh cut along the sealant to the substrateinterface (Fig. 9).8.1.1 Place the test specimen in the tensile testing machinewith the substrate secured to the fixed member and the looseend of the wire mesh sc
37、reen secured to the movable member atan angle of 180 (Fig. 10).8.1.2 Pull the screen at a rate of 50 mm (2 in.)/min for a totalof 1 min (Fig. 11).8.1.2.1 If the screen breaks during the testing, disregard thevalue. If possible, undercut the sealant with a razor knife andrepeat the test. If the scree
38、n continues to break, prepare newtest samples using a higher strength 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 knifeand repeat the test. If adhesive failure to the screen continues,prepare new test samples usi
39、ng a more thoroughly cleaned orprimed, or both, wire mesh screen. If necessary, use a materialother than a wire mesh screen.8.1.2.3 If the adhesion-in-peel test sample shows adhesivefailure to the screen in two repeated attempts but peel forcevalues are above the specified requirements, further samp
40、letesting may not be required. In such cases, report failure modeas screen delamination, since adhesive or cohesive failure ofthe sealant to the substrate is not fully established. The screenshould be pulled for a total of 1 min as described in 8.1.2.NOTE 1DiscussionSome sealants may have a non-homo
41、geneousmode of failure during the initial adhesion-in-peel testing. During the first30 to 60 s of testing, the sealant may achieve a steady state and longer testduration may be needed to accurately assess the failure mode of thesealant.FIG. 6 Applying Second Bead of SealantFIG. 7 Tooling Second Bead
42、 of Sealant with Special Tooling De-viceSideBFIG. 8 Finished Adhesion-in-Peel Test SamplesFIG. 9 Cut Along Sealant/Substrate Interface with Razor KnifeC794 15a48.1.3 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
43、).8.1.5 Observe and record the approximate percentages ofsealant failure modes over the total test area. Sealant failure isdescribed as either adhesive or cohesive failure. See Fig. 12 foran example of each failure mode. Failure observed within thesubstrate (that is, paint removal, etc.) should be r
44、eported assubstrate failure.8.2 Water Immersion TestUsing either four separate testspecimens or the same test specimen used for dry adhesiontesting and following completion of standard cure as describedin 7.1.12, immerse the test samples for 7 days in distilled waterconditioned to 23 6 2C (73 6 4F).
45、 Mortar and concretespecimen should be placed in a separate container from glassand aluminum specimen because the high alkali conditiongenerated could have an adverse effect on the glass andaluminum.8.2.1 Following water immersion, remove the test samples,lightly dry with a cloth or paper towel and
46、test within 10 minas described in 8.1 through 8.1.5.8.3 Additional conditions may be used including differentcure conditions, different water temperature or duration ofimmersion, exposure of sealant to chemicals or other materialsor exposure to ultraviolet radiation, heat or weathering.9. Report9.1
47、Report the following information for each sampletested:9.1.1 Description of substrate test sample, that is, bronzeanodized aluminum, clear float glass, polished granite, etc.9.1.2 Description of substrate surface preparation andcleaning,9.1.3 Description of screen cleaning, and priming, ifperformed,
48、9.1.4 Identification of the type of sealant, such as single- ormulti-component, color, product name, etc.,9.1.5 Identification of primer type if used or record “noprimer”,FIG. 10 Adhesion-in-Peel Test Specimen Secured in Tensile Test-ing MachineFIG. 11 Wire Mesh Screen Pulled at 180 on Tensile Testi
49、ng Ma-chineNOTE 1Left: Cohesive FailureRight: Adhesive FailureFIG. 12 Examples of Cohesive Failure and Adhesive FailureC794 15a59.1.6 Average and peak peel strength in Newton (pound-force) for each adhesion-in-peel test,9.1.7 Percent sealant failure type for each adhesion-in-peeltest.9.1.8 Variation, if any, from the specified test procedure.Examples of common variation in the test method include:9.1.8.1 Use of a material other than a wire mesh screen, thatis, polyester mesh, fiberglass mesh, airplane cloth, etc.,9.1.8.2 Screen width different than 2
