ASTM_C_1253_-_14.pdf

Designation:C125314Standard Test Method forDetermining the Outgassing Potential of Sealant Backing1This standard is issued under the fixed designation C1253;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 test method provides a procedure for determiningthe outgassing potential of a sealant backing when it ispunctured during or after installation,with the puncture occur-ring before the sealant cures.1.2 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.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 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 SealantsC1193 Guide for Use of Joint Sealants3.Terminology3.1 DefinitionsRefer to Terminology C717 for the follow-ing terms used in this test method:sealant,cure,sealantbacking,joint,substrate,non-sag sealant,tooling,and outgas-sing.4.Summary of Test Method4.1 A sample of sealant backing material is placed betweennonporous substrates in a compressed condition,simulating theplacing of sealant backing on a job site.The sealant backing isthen punctured at intervals along its exposed face.A sealant isapplied immediately after puncture,and it is tooled to make atypical butt joint as described in Guide C1193.After tooling,the specimen is placed in an air circulating oven at elevatedtemperature for 1 h and then removed.The specimen iscompressed 1212%of its diameter and in the compressed statereturned to the oven.The specimen is removed after anotherhour in the oven and compressed another 1212%and returnedto the oven,where it remains for another 2 h.The specimen isremoved from the oven,and the sealant is allowed to finishcuring at room temperature,while in the compressed condition.The sealant is then removed from the specimen,and the backface(the face against the sealant backing)is examined.Thesealant is slit in half along its length and the size of any voidsestimated.5.Significance and Use5.1 This test method is an indicator of a potential sealingproblem that could occur if a sealant backing is flawed inmanufacture or transportation to the job site,or abused duringthe installation.If flawed,some sealant backing materials,incombination with certain environmental conditions,canoutgas,generating voids in the applied sealant before thesealant cures,thereby potentially compromising the curedsealants intended performance.5.2 Voids are also known to be caused by other means andunder certain conditions such as air entrapment during sealantapplication,trapped air in the substrate releasing into theuncured sealant,incompatibility of the sealant with the sealantbacking or substrate,or inhospitable installation conditions inthe field.This test method is limited to identifying theoutgassing potential of a punctured sealant backing by forma-tion of a void in the soft uncured sealant under conditions ofheat and compression.6.Apparatus6.1 Air Circulating Oven,capable of maintaining a tempera-ture of 122F(50C).6.2 Test Frame and Stylus,as described in Annex A1.7.Test Specimens7.1 Sealant backing should be 307.8-mm(12-in.)long andof a width appropriate for use in 12.7-mm(12-in.)wide joints.The proper width will be as specified by the sealant backingmanufacturer.NOTE1The test method is specifically for 12.7-mm(12-in.)widejoints and sealant backings used in such joints.The procedure is adapted1This test method is under the jurisdiction ofASTM Committee C24 on BuildingSeals and Sealants and is the direct responsibility of Subcommittee C24.20 onGeneral Test Methods.Current edition approved Feb.1,2014.Published March 2014.Originallyapproved in 1993.Last previous edition approved in 2009 as C125393(2009).DOI:10.1520/C1253-14.2For 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 easily to either wider or narrower joints if all compression is consideredas a percent of the joint width.8.Conditioning8.1 Condition all sealant backing and sealants at standardconditions in accordance with Terminology C717 for a mini-mum of 12 h prior to testing.9.Procedure9.1 Prepare the test specimen by placing the sealant backingin the simulated joint apparatus(Fig.A1.1 and Fig.A1.2),which has been adjusted to a 12.7-mm(12-in.)wide opening.Exercis