1、Designation: C 1253 93 (Reapproved 2009)Standard Test Method forDetermining the Outgassing Potential of Sealant Backing1This standard is issued under the fixed designation C 1253; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、 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 is
3、punctured 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,
4、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:2C 717C 11933. Terminology3.1 DefinitionsRefer to Term
5、inology C 717 for the fol-lowing 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 th
6、eplacing 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 C 1193. After tooling,the specimen is placed in an air circulating o
7、ven 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 sp
8、ecimen 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 si
9、ze 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, incombinati
10、on with certain environmental conditions, can out-gas, generating voids in the applied sealant before the sealantcures, thereby potentially compromising the cured sealantsintended performance.5.2 Voids are also known to be caused by other means andunder certain conditions such as air entrapment duri
11、ng 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 b
12、acking 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
13、-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.NOTE 1The test method is specifically for 12.7-mm (12-in.) widejoints and sealant backings used in such joints. The procedure is adapted1This test met
14、hod 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 June 1, 2009. Published June 2009. Originallyapproved in 1993. Last previous edition approved in 2005 as C 125393(2
15、005).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.1Copyright ASTM International, 100 Barr Harbor Drive, PO
16、 Box C700, West Conshohocken, PA 19428-2959, United States.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 for a minimum of 12 h prior to testing. Standardcon
17、ditions for this procedure are 23 6 2C (73.4 6 3.6F) and50 6 5 % relative humidity.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.Exercise care not to abuse
18、or puncture the sealant backingduring installation.9.2 Use the stylus (Fig. A1.3) to form six 9.5-mm (38-in.)deep punctures starting 38-mm (112-in.) from the end, spaced25.4-mm (1-in.) apart, and centered on the width of the sealantbacking. The marks on the channel, used to form the joint, aidin loc
19、ating the quick, even placement of the punctures.9.2.1 If the sealant backing has a tendency to slip down inthe joint during the puncturing, slip a temporary solid form(such as a length of wood) beneath the backing to hold it inplace. Remove this when the puncturing is complete.9.2.2 Time is a criti
20、cal factor, so make all six punctures in 1min or less.9.3 Apply sealant over the sealant backing from a typicalcaulking gun in a pushing motion so air is not trapped betweensealant and sealant backing. Tool the sealant to achieve aslightly concave surface. Consistent with good sealing prac-tices out
21、lined in Guide C 1193, the tooling should be done withsufficient pressure to ensure that the sealant wets the top of thesealant backing and the wall of the simulated joint.9.3.1 While any non-sag sealant can be used, a clear sealantis preferred since it permits quick identification of any flaws,void
22、s, or bubbles resulting from the installation process. Theclear sealant also aids in the detection of voids caused bysealant backing outgassing.9.3.2 Time is a critical factor, so apply and seal the sealantwithin 2 min after completing the puncturing.9.3.3 Prepare and test a control specimen for thi
23、s testmethod identically to the test specimen, except do not puncturethe sealant backing.9.4 Place the test and control specimens in a 50C (122F)oven for 1 h.9.5 Remove the specimens from the oven, and turn theadjusting screws so that the joint is compressed 1212 % 1.6mm (116 in.) for a 12.7-mm (12-
24、in.) joint, and place them backin the oven for 1 h.9.6 Remove the specimens from oven, turn the screws tocompress the joint another 1212 % of the original dimension1.6 mm (116 in.) for a 12.7-mm (12-in.) joint, and place themback in the oven for another 2 h.9.7 Remove the specimens from the oven and
25、 allow thesealant to cure at standard conditions for 2 weeks or for thesealant manufacturers recommended cure time.9.8 If a clear sealant was used, bubbles will be evident ifthey occurred. In all cases, slit the sealant along its entirelength at the mid point of the joint width using a sharp razor.9
26、.8.1 If properly performed, the slit will pass through anyvoids that have formed. Cut the sealant away from the edge ofthe substrate (a knife generally works better than a razor).Remove the two sealant halves from the joint and examine thesize of the voids.10. Report10.1 Report the test results and
27、observations on the formshown in Fig. 1.10.2 If no voids occur, indicate “None.”10.3 If voids are present and they occur directly over thepuncture points, indicate the number of voids. Measure thelength and width of the voids to the nearest millimeter.Calculate the average diameter of the void.10.4
28、In the comments section, note whether voids occurredwhere no punctures were present, their frequency, size, andother pertinent observations.11. Precision and Bias311.1 The precision and bias statement based on the numberof voids is as follows:11.1.1 The repeatability (within a given laboratory) inte
29、rvalfor five materials tested by four laboratories is 2.553 voids. Inthe future use of this test method, the difference between twotest results obtained in the same laboratory on the samematerial will be expected to exceed 2.553 voids only approxi-mately 5 % of the time.11.1.2 The reproducibility (b
30、etween given laboratories) in-terval for five materials tested by four laboratories is 2.637voids. In the future use of this test method, the differencebetween two tests results obtained in a different laboratory on3Supporting data have been filed at ASTM Headquarters. Request RR: C24-1038FIG. 1 For
31、m for Test Results and ObservationsC 1253 93 (2009)2the same material will be expected to exceed 2.637 voids onlyapproximately 5 % of the time.11.2 The precision and bias statement based on the size ofthe voids is as follows:11.2.1 The repeatability (within a given laboratory) intervalfor five mater
32、ials tested by four laboratories is 2.671 mm(0.105 in.). In the future use of this test method, the differencebetween two test results obtained in the same laboratory on thesame material will be expected to exceed 2.671 mm (0.105 in.)only approximately 5 % of the time.11.2.2 The reproducibility (bet
33、ween given laboratories) in-terval for five materials tested by four laboratories is 5.365 mm(0.21 in.). In the future use of this test method, the differencebetween two test results obtained in a different laboratory onthe same material will be expected to exceed 5.365 mm (0.21in.) only approximate
34、ly 5 % of the time.12. Keywords12.1 outgassing; sealant backingANNEX(Mandatory Information)A1. TEST APPARATUSA1.1 The test apparatus consists of a base plate (see Fig.A1.1 and Fig. A1.2) and a fixed metal angle bolted to the baseplate. A square metal tube is placed next to the metal angle. Aspace is
35、 created for the sealant backing and sealant by placingthe other square metal tube and slotted metal angle on the baseplate. The slotted holes permit the accommodation of differentsizes of sealant backing. The vertical leg of the slotted metalangle has two threaded holes, one at each end to receive
36、thumbscrews for compressing the specimen.A1.2 Fig. A1.3 shows the stylus for making punctures inthe sealant backing.FIG. A1.1 End View of Test ApparatusC 1253 93 (2009)3FIG. A1.2 Top View of Test ApparatusFIG. A1.3 Side View of Puncture StylusC 1253 93 (2009)4ASTM International takes no position res
37、pecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This
38、standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM Intern
39、ational Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown be
40、low.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).C 1253 93 (2009)5
