1、Designation: D4798/D4798M 11Standard Practice forAccelerated Weathering Test Conditions and Procedures forBituminous Materials (Xenon-Arc Method)1This standard is issued under the fixed designation D4798/D4798M; the number immediately following the designation indicates theyear of original adoption
2、or, in the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers test conditions and procedures forxenon-arc exposures ac
3、cording to Practices G151 and G155 forbituminous roofing and waterproofing materials. (See Termi-nology G113.)1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem sha
4、ll be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.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
5、-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1669 Practice for Preparation of Test Panels for Acceler-ated and Outdoor Weathering of Bituminous CoatingsD1670 Test Method for Failure End Point i
6、n Acceleratedand Outdoor Weathering of Bituminous MaterialsG113 Terminology Relating to Natural andArtificial Weath-ering Tests of Nonmetallic MaterialsG141 Guide for Addressing Variability in Exposure Testingof Nonmetallic MaterialsG147 Practice for Conditioning and Handling of Nonmetal-lic Materia
7、ls for Natural and Artificial Weathering TestsG151 Practice for Exposing Nonmetallic Materials in Ac-celerated Test Devices that Use Laboratory Light SourcesG155 Practice for Operating XenonArc LightApparatus forExposure of Non-Metallic MaterialsG169 Guide for Application of Basic Statistical Method
8、s toWeathering Tests3. Summary of Test Method3.1 Thin films of bitumen are uniformly applied to alumi-num panels. Shingles and similar products are cut to size andexposed to specified cycles of temperature, light, and water. Achoice of two test cycles is given along with options fordetermining the p
9、eriod of exposure and evaluating results.4. Significance and Use4.1 Tests conducted according to this practice are used tocompare the weathering characteristics of bituminous materialsversus a control material of known outdoor durability. It is notpossible to establish a single relationship that is
10、applicable toall materials between time in accelerated tests conductedaccording to this practice and time in natural weatheringbecause (1) there are geographical climatic variations, localweather variations, and variations in local pollutants, and (2)the relation between accelerated and natural weat
11、hering ismaterial dependent with differences in acceleration factorsbetween materials as well as for different formulations of thesame material. Guide G141 provides guidance regarding vari-ability in outdoor and accelerated weathering tests and aboutthe use of control materials.NOTE 1It is recommend
12、ed that outdoor weathering be used tovalidate the laboratory accelerated test in terms of performance ranking.NOTE 2This practice can be used for other than bituminous materials,but the significance and use have not been evaluated.5. Apparatus5.1 The xenon-arc apparatus used shall conform to therequ
13、irements defined in Practices G151 and G155.5.2 FiltersDaylight filter as described in Practice G155.5.3 RadiometerThe use of a radiometer to monitor andcontrol the amount of radiant energy received at the specimenis required. The use of the radiometer shall comply with therequirements in Practice G
14、151.1This practice is under the jurisdiction ofASTM Committee D08 on Roofing andWaterproofing and is the direct responsibility of Subcommittee D08.02 on SteepRoofing Products and Assemblies.Current edition approved Jan. 1, 2011. Published January 2011. Originallyapproved in 1988. Last previous editi
15、on approved in 2010 as D4798/D4798M 10.DOI: 10.1520/D4798_D4798M-11.2For 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 w
16、ebsite.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Test Specimens6.1 Unless otherwise agreed upon, test specimens shall beapproximately 70 by 150 mm 234 by 578 in. Bituminousmaterials with adequate flow resistance shall be app
17、lied asuniform coatings on aluminum panels in accordance withPractice D1669. Fabricated materials such as bituminousroofing, shingles, and similar products shall be cut to size andtheir weather surfaces exposed. Bituminous materials that aretoo flexible to sustain their own weight when exposed in av
18、ertical position are permitted to be mounted on aluminumpanels using stainless steel or other non-rusting clips.6.1.1 Unless otherwise specified, expose at least three rep-licate specimens of each test and control material.6.1.2 Other test specimen sizes are permitted to be used toprovide sufficient
19、 material for postexposure testing whendesired.6.1.3 Follow the procedures described in Practice G147 foridentification, conditioning, and handling of specimens of testand control materials before, during, and after exposure.6.1.4 Do not mask the face of a specimen for the purpose ofshowing on one p
20、anel the effects of various exposure times.Misleading results may be obtained by this method, since themasked portion of the specimen is still exposed to temperatureand humidity cycles that in many cases will affect results.7. Procedure7.1 Proceed in accordance with Section 9 of Practice G155.7.2 Wa
21、ter Purity:7.2.1 The purity of water used for specimen spray is veryimportant. Without proper treatment to remove cations, anions,organics, and particularly silica, exposed panels will developspots or stains that may not occur in exterior exposures.7.2.2 Follow the requirements for water purity desc
22、ribed inPractice G151.7.2.3 When specimens are found to have deposits or stainsafter exposure in the apparatus, the water purity must bechecked to determine if it meets the requirements of 7.2.2.Onsome occasions, exposed specimens can be contaminated bydeposits from bacteria that can grow in the pur
23、ified water usedfor specimen spray. When bacterial contamination is detected,the entire system used for specimen water spray must beflushed with chlorine and thoroughly rinsed before resumingexposures.7.2.4 The temperature of water used for specimen sprayshall be 7.2 6 3C 45 6 5F.7.2.5 When the wate
24、r purity requirements above are met andthere is disagreement between parties on the extent of problemscaused by stain or deposit, run referee tests in at least one otherlaboratory that can meet the water quality requirements de-scribed in 7.2.7.3 Unless otherwise specified, operate the apparatus con
25、-tinuously with the device programmed to control irradiance at340 nm at 0.35 W/(m2nm) and operating according to theconditions described in Cycle A or Cycle B. Unless otherwisespecified, place specimens in an exposure area where irradi-ance is at least 90 % of the maximum irradiance measuredwithin t
26、he exposure area. In devices with rotating specimenracks, fill any empty spaces with blank metal panels in order toproperly maintain the conditions within the exposure area.NOTE 3Information about the exposure areas that meet the 90 %irradiance uniformity requirement is available from the manufactur
27、ers ofthe exposure devices.7.3.1 During equilibrium operation, the maximum allow-able deviation from the desired irradiance at 340 nm is 60.02W/(m2nm) and the maximum allowable deviation from thedesired uninsulated black panel temperature is 62.5C. Duringequilibrium conditions, when the meter or sen
28、sor indicatingirradiance or black panel temperature shows a value that isoutside the limits described above, discontinue the test andcorrect the cause of the problem before continuing.7.3.1.1 Cycle A-151-min light-only exposure with deviceprogrammed to produce an uninsulated black panel tempera-ture
29、 of 60C at equilibrium conditions. This is followed by a9-min period with the light on and with water sprayed on thefront of the specimens.7.3.1.2 Cycle A-2The same as Cycle A-1, except thatwater is sprayed on both the front and back surfaces of thespecimens.7.3.1.3 Cycle B-160 min with light on and
30、 water sprayedon the front of the specimens, 90 min light-only exposure, 120min with light on and water sprayed on the front of thespecimens, 990 min light-only exposure, 180 min of coldexposure. Program the device to produce an uninsulated blackpanel temperature of 60C at equilibrium conditions dur
31、ing thelight-only periods.7.3.1.4 Cycle B-2The same as Cycle B-1, except thatwater is sprayed on both the front and back surfaces of thespecimens.NOTE 4Typically water is sprayed only on the front surface of thespecimens. Some users operate their equipment so that water is sprayed onboth the front a
32、nd back surfaces. Results between exposures conductedwith these two types of water spray may differ.7.3.1.5 For the cold exposure, panels shall be placed in afreezer that is controlled at 18C 0F. During equilibriumoperation, the maximum allowable deviation from this tem-perature is 65C 69F. The time
33、 to transfer test specimensfrom the xenon-arc device to the freezer or from the freezerback to the xenon arc device (including any time used forinspection of the test specimens) shall not exceed 15 min. Thistime shall not be included as part of the 24 h exposure cycle.7.3.2 Some users use equipment
34、capable of controllingchamber air temperature and/or relative humidity. When cham-ber air temperature is controlled, program the device to controlchamber air temperature at 44C. For exposures in whichrelative humidity is controlled, it is recommended that thedevice be programmed to control at 50 % R
35、H. When chamberair temperature and/or relative humidity are controlled, thesetting of these parameters must be included in the test report.7.3.2.1 When chamber air temperature is controlled, themaximum allowable deviation from the desired temperature is62C. When the relative humidity is controlled,
36、the maximumallowable deviation from the desired relative humidity duringequilibrium conditions is 610 % RH. During equilibriumconditions, when the meter or sensor indicating chamber airtemperature or relative humidity indicates a value outside theD4798/D4798M 112limits described above, discontinue t
37、he test and correct thecause of the problem before continuing.NOTE 5Historically, tests run according to this practice have been runwithout controlling humidity or chamber air temperature. Tests run withhumidity or chamber air temperature controlled at the recommended valuemay produce different resu
38、lts.8. Period of Exposure and Evaluation of Test Results8.1 The duration of the exposure under this practice shall beone of the following:8.1.1 A mutually agreed upon number of 24-h cycles ofoperation in accordance with either Cycle A or Cycle B,8.1.2 The number of 24-h cycles required to produce am
39、utually agreed upon minimum amount of change in the testspecimen, or8.1.3 The number of 24-h cycles required to producemutually agreed upon minimum acceptable changes in eitherthe test specimen or a mutually agreed upon control sample.8.2 Changes in the exposed specimens are either evaluatedvisually
40、 at the end of each 24-h cycle by comparing them withunexposed specimens, or evaluated in terms of the number ofcycles required to produce property changes as determined byTest Method D1670.NOTE 6When changes in properties of the test and control specimensare determined, a statistical analysis on th
41、e results is recommended todetermine if there is a difference between the test and control materials.Guide G169 provides information about the use of statistical analysis forresults from weathering exposures.9. Report9.1 In addition to the items specified in Practice G151, thereport shall include th
42、e following information:9.1.1 Cycle used (refer to this practice),9.1.2 Level of irradiance at 340 nm, uninsulated black paneltemperature, and, when controlled, relative humidity andchamber air temperature,9.1.3 Coating thickness used, and9.1.4 Method of sample repositioning, if used, or othermeans
43、of assuring equal radiant exposure on all specimens orcompensation for differences in irradiance within the exposurechamber.10. Precision and Bias10.1 PrecisionThe repeatability of results obtained inexposures conducted according to this practice will vary withthe materials being tested, the materia
44、l property being mea-sured, and the specific test conditions and cycles that are used.It is essential to determine reproducibility of the exposure/property measurement process when using the results fromexposures conducted according to this practice in productspecifications.10.2 BiasBias cannot be d
45、etermined because no accept-able standard weathering reference materials are available.11. Keywords11.1 accelerated weathering; bituminous materials; degrada-tion; exposure; light exposure; roofing; ultraviolet; waterproof-ing; xenon-arcASTM International takes no position respecting the validity of
46、 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 standard is subject to
47、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 International Headquarters. Y
48、our 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 below.This standard is co
49、pyrighted 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/).D4798/D4798M 113
