1、Designation:C79305(Reapproved 2017)Standard Test Method forEffects of Laboratory Accelerated Weathering onElastomeric Joint Sealants1This standard is issued under the fixed designation C793;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revi
2、sion,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 cove
3、rs a laboratory procedure fordetermining the effects of accelerated weathering on cured-in-place elastomeric joint sealants(single-and multicomponent)for use in building construction.1.2 The values stated in SI units are to be regarded as thestandard.The values in parentheses are for information onl
4、y.1.3 The committee with jurisdiction over this standard is notaware of any comparable standards published by other ASTMcommittees or other organizations.1.4 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
5、 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 SealantsC1442 Practice for Conducting Tests on Sealants UsingArtificial Weathering
6、ApparatusG151 Practice for Exposing Nonmetallic Materials inAccel-erated Test Devices that Use Laboratory Light Sources3.Terminology3.1 DefinitionsSee Terminology C717 for applicable defi-nitions of the following terms:cure,elastomeric,joint,sealant,and substrate.4.Summary of Test Method4.1 Three se
7、alant specimens are spread on aluminum platesand exposed in one of the laboratory accelerated weatheringchambers specified in Section 6 and operated in accordancewith specifications in Section 8 and Practice C1442.4.2 Following this treatment the specimens are exposed for24 h in a freezer maintained
8、 at 26 6 2C(15 6 4F).4.3 At the end of the cold exposure,the specimens are bentover a mandrel within 1 s at the specified temperature.5.Significance and Use5.1 It is known that solar radiation contributes to thedegradation of sealants in exterior building joints.The use of alaboratory accelerated we
9、athering machine with actinicradiation,moisture and heat appears to be a feasible means togive indications of early degradation by the appearance ofsealant cracking.However,simulated weather factors in com-bination with extension may produce more severe degradationthan weather factors only.Therefore
10、,the effect of the weath-ering test is made more sensitive by the addition of the bendingof the specimen at cold temperature.6.Apparatus6.1 Exposure ApparatusThe exposure apparatus shall beone of the three types of laboratory accelerated weatheringdevices described in Practice C1442 that use either
11、xenon arc,fluorescent UV,or open flame carbon arc radiation.ConsultPractice C1442,Section 7 for the differences in test parametersamong the devices.Because of differences in test conditions,test results may differ with the type of device used.The choiceof device shall be by mutual agreement among th
12、e interestedparties.6.2 Freezer or Cold Box,having a temperature controlledat 26 6 2C(15 6 4F).6.3 Rectangular Brass Frame,with inside dimensions 130by 40 by 3 mm(5 by 112by18in.).6.4 Aluminum Plates,three,each 152 by 80 by 0.3 mm(6 by3 by 0.01 in.).6.5 Steel Mandrel,12.7 mm(12in.)in diameter and ab
13、out102 mm(4 in.)long.6.6 Thin-Bladed Knife.1This test method is under the jurisdiction ofASTM Committee C24 on BuildingSeals and Sealants and is the direct responsibility of Subcommittee C24.40 onWeathering.Current edition approved Feb.1,2017.Published March 2017.Originallyapproved in 1975.Last prev
14、ious edition approved in 2010 as C793 05(2010).DOI:10.1520/C0793-05R17.2For 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 web
15、site.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 Inter
16、national Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 6.7 Straightedge,metal or plastic,about 152 mm(6 in.)long.6.8 Spatula,steel,about 152 mm(6 in.)long.7.Standard Test Conditions7.1 Unless otherwise specified by those authorizing the test,standard conditions shall be as described in Terminology C717.8.Procedure8.1 Test of Multicomponent Sealants:8.1.1 Condition at least 200 g of base compound andappropriate amount of cu
