1、Designation: C1253 14Standard 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 revisi
2、on. 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
3、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
4、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 Joi
5、nt 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
6、 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 too
7、ling,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
8、 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. The
9、sealant 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
10、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 andund
11、er 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
12、 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 Sp
13、ecimens7.1 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.NOTE 1The test method is specifically for 12.7-mm (12-in.) widejoints and sealant backings used in su
14、ch 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. La
15、st 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 onth
16、e ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1easily 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
17、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.Exercise care n
18、ot to abuse 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 join
19、t, aidin locating 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 Tim
20、e is a critical 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 pr
21、ac-tices outlined in Guide C1193, 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
22、 flaws,voids, 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 speci
23、men for this 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 1
24、2.7-mm (12-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 t
25、he oven and 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 sh
26、arp razor.9.8.1 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 r
27、esults and 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
28、 void.10.4 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 labor
29、atory) intervalfor 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.3Supporting data h
30、ave been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:C24-1038.FIG. 1 Form for Test Results and ObservationsC1253 14211.1.2 The reproducibility (between given laboratories) in-terval for five materials tested by four laboratories is 2.637voids. In the
31、future use of this test method, the differencebetween two tests results obtained in a different laboratory onthe 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 repeata
32、bility (within a given laboratory) intervalfor five materials 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 appr
33、oximately 5 % of the time.11.2.2 The reproducibility (between 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
34、be expected to exceed 5.365 mm (0.21in.) only approximately 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 squar
35、e metal tube is placed next to the metal angle. Aspace is 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 metal
36、angle has two threaded holes, one at each end to receive thumbscrews for compressing the specimen.A1.2 Fig.A1.3 shows the stylus for making punctures in thesealant backing.FIG. A1.1 End View of Test ApparatusC1253 143FIG. A1.2 Top View of Test ApparatusFIG. A1.3 Side View of Puncture StylusC1253 144
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40、ee on Standards, at the address shown below.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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).C1253 145
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