ASTM_C_794_-_15a.pdf

Designation:C79415aStandard 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 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 fordetermining 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 information 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 standard 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 Practice 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 test 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 mesh 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 simulates 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-peeltest 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 substrates.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 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 the 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 with 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.Last 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 ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.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 indicator 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 joi