ASTM_C_1851_-_18.pdf

Designation:C185118Standard Practice forDetermining the Extent of Cracking in a Sealant using theDifference between the Compressive and Tensile Modulus1This standard is issued under the fixed designation C1851;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.1.Scope1.1 This practice covers a procedure for quantitativelydetermining the extent of cracking in a sealant sample byevaluating the difference between the measured compressiveand tensile modulus of a sealant relative to an unexposed oruncracked version of the same sealant.The cracks will reducethe area of the sealant in the tensile modulus,but in thecompressive modulus measurement they will not change thearea over which the modulus is determined.1.2 The values in SI units are to be regarded as standard.The values in parentheses are for information only.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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2C717 Terminology of Building Seals and SealantsC719 Test Method for Adhesion and Cohesion of Elasto-meric Joint Sealants Under Cyclic Movement(HockmanCycle)C1735 Test Method for Measuring the Time DependentModulus of Sealants Using Stress RelaxationE631 Terminology of Building Constructions3.Terminology3.1 Definitions:3.1.1 For definitions of terms used in this practice,refer toTerminologies E631 and C717.4.Summary of Practice4.1 This practice consists of measuring the modulus of thesealant using Test Method C1735 in both tension and compres-sion.Once these values have been determined the formulapresented in this practice will be used to determine the degreeof cracking in the sealant relative to an unexposed or uncrackedsample of the same sealant.4.2 The motivation for this practice is to quantitativelydetermine the extent of cracking in the sealant.This measure-ment is currently determined with a qualitative measure ofcracking determined by visual inspection.The degree ofcracking has been used as a measure of performance forsealant.4.3 This practice will enable determination of the percent ofcracking of a sealant relative to an unexpected or uncrackedvesion of the same sealant.5.Significance and Use5.1 The intent of this practice is to quantitatively determinethe amount of cracking of a sealant relative to an unexposed oruncracked sample.Some samples of sealant have been ob-served to exhibit some degree of cracking some period afterinstallation.The degree of cracking is assessed visually in aqualitative manner that takes into account the area of the cracksat the exposed surface of the sealant,but does not take intoaccount the depth or profile of the cracks.The degree ofcracking in the sealant has been used as an indication ofperformance change.6.Procedure6.1 The modulus of the sealant is determined in compres-sion and separately in tension using Test Method C1735.Thesevalues are determined from a new sample(the unexposedreference without any cracking),and the sample of interest.6.2 From the four modulus measurements obtained fromTest Method C1735,determine the value of the modulus at100 s for each of these four conditions:1This practice is under the jurisdiction of ASTM Committee C24 on BuildingSeals and Sealants and is the direct responsibility of Subcommittee C24.20 onGeneral Test Methods.Current edition approved Feb.1,2018.Published March 2018.DOI:10.1520/C1851-18.2For 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 StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 6.2.1 New Sample(the unexposed reference without anycracking),compression(E100,bo,C),6.2.2 New Sample(the unexposed reference without anycracking),Tension(E100,bo,T),6.2.3 Test Sample,Compression,(E100,C),6.2.