1、Designation: G160 03 (Reapproved 2009)G160 12Standard Practice forEvaluating Microbial Susceptibility of Nonmetallic MaterialsBy Laboratory Soil Burial1This standard is issued under the fixed designation G160; the number immediately following the designation indicates the year oforiginal adoption or
2、, 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 practice is limited to the method of conducting an evaluation of a nonmeta
3、llic materials microbiological susceptibilitywhen in contact with the natural environment of the soil. soil under use conditions. This practice is intended for use on solidmaterial test specimens that are no larger than approximately 2 cm (0.7934 in.) thick and 100 cm2 (20(15.5 in.2) or on film form
4、ingmaterials such as coatings which may be tested in the form of films at least 50 by 50 mm (2 by 2 in.) in size. This practice maybe applied to articles that do not spend the majority of their service life in soil.1.2 A wide variety of properties may be affected by microbial attack depending on mat
5、erial or item characteristics. Standardmethods (where available) should be used for each different property to be evaluated. This practice does not attempt to enumerateall of the possible properties of interest nor specify the most appropriate test for those properties. Test methods must, however, b
6、eappropriate to the material being tested.1.3 It Materials intended for use in soil burial applications are often subjected to periods of exposure to solar radiation and otherelements of weather for some time before they are buried. Because these exposures may alter the ability of a material to resi
7、st theeffects of soil-borne microorganisms, it is recommended that this practice be combined with appropriate environmental exposures(for example, sunlightsolar simulating weathering devices, the hydrolytic effects of extended aqueous contact, or extraneousnutrients) or fabrication into articles (fo
8、r example, adhesive bonding of seams) which may promote microbiological susceptibilityduring the service life of the material.1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are provided for informationpurposes only.1.5 This standard does not purport
9、 to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2G154 Pra
10、ctice for Operating Fluorescent Ultraviolet (UV) Lamp Apparatus for Exposure of Nonmetallic MaterialsG155 Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-Metallic Materials3. Significance and Use3.1 These results may be used to compare the susceptibility of materials when expose
11、d to this test procedure.3.2 Microbiological susceptibility may be reflected by a number of changes including staining, weight loss, or reduction intensile or flexural strength.3.3 This practice may be considered an inoculation with a mixed culture of fungi and bacteria.4. Soil4.1 Composition Soil s
12、hall be composed of equal parts of fertile topsoil (soil with a high clay content should not be used),well-rotted and shredded horse manure, and coarse sand (10 to 40 mesh).1 This practice is under the jurisdiction of Committee G03 on Weathering and Durability and is the direct responsibility of Sub
13、committee G03.04 on BiologicalDeterioration.Current edition approved June 1, 2009Nov. 1, 2012. Published July 2009 January 2013. Originally approved in 1998. Last previous edition approved in 20032009 as G160 03.03(2009). DOI: 10.1520/G0160-03R09.10.1520/G0160-12.2 For referencedASTM standards, visi
14、t theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standar
15、d an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM i
16、s to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.2 MixingThe soil composition of 3.14.1 should be prepared by simple mixing and sifting through 14-in. mesh screen.4.3 AgingThe mixture is aged
17、for three months and resifted twice at four-week intervals during the three months. After threemonths, a viability control of untreated cotton cloth, 400 to 475 g/m2 (12 to 14 oz/yd2), buried in the soil shall have a tensilestrength loss of at least 50 % after five days.NOTE 1The soil mixture may be
18、 used for sequential tests as long as the cotton cloth control degrades within the specified time period.4.4 pHThe soil shall have a pH between 6.5 to 7.5, checked periodically, and maintained by the addition of ground limestoneto raise the pH or flowers of sulfur to lower the pH. The soil pH may be
19、 taken by dispersing 1 weight part soil in 20 parts of water,shaking or stirring, then allowing the mix to settle for 1 h. The pH is measured with indicator paper, electrodes, or by titration.4.5 MoistureThe soil shall be maintained at between 20 and 30 % moisture, based on the dry weight of the soi
20、l. (The percentmoisture is calculated by weighing approximately 50 mL of a representative portion and taking the portion to constant weight byplacing the soil in an oven at a temperature of 101 to 106C.) Water lost during use as a result of evaporation shall be replacedwithout deforming the soil bed
21、. If the surrounding atmosphere is maintained at 85 to 95 % relative humidity, this loss is negligible,however, the moisture level should be periodically measured.5. Apparatus5.1 Soil Container The container shall be any material of suitable mechanical strength and chemical/microbial resistance and,
22、if porous, shall be lined with impermeable material. It shall be of any size that is convenient to handle and having a depth of atleast 12.7 cm (5 in.).5.2 External EnvironmentAn apparatus capable of maintaining a temperature of 30 6 2C (86 6 3.6F) and a relativehumidity to 85 to 95 %, into which th
23、e assembled container is inserted, is necessary. An incubator or controlled tropical chamberis adequate.6. Test Specimens6.1 Completely fabricated parts or sections cut from fabricated parts may be used as test specimens. The simplest specimen maybe a 50- by 50-mm (2- by 2-in.) piece, a 50-mm (2-in.
24、) diameter piece, or a piece (rod or tubing) at least 76 mm (3 in.) long cutfrom the material to be tested.6.2 Film-forming materials such as coatings may be tested in the form of films at least 50 by 50 mm (2 by 2 in.) in size. Suchfilms may be prepared by casting on glass and stripping after cure
25、or by impregnating (completely covering) filter paper or ignitedglass fabric.6.3 For visual evaluation, a minimum of three test specimens shall be used.6.4 In devising a test program intended to reveal quantitative changes occurring during and after exposure, an adequate numberof specimens should be
26、 evaluated to establish a valid value for the original property. For example, if five replicate test specimensare required to establish a tensile strength of a film material, at least that number of test specimens shall be removed and testedfor each exposure period. It is to be expected that values
27、of physical or mechanical properties at various stages of fungal attackwill be variable. The ASTM Manual 73 may be used as a guide.7. Solar-Simulating Weathering Devices7.1 For those soil burial applications in which the materials are expected to be exposed to environmental conditions, includingsola
28、r radiation, it is recommended that they be exposed in a laboratory accelerated weathering device prior to soil burial. The typeand duration of exposure shall be agreed upon by interested parties. The duration shall be of sufficient length, known by previousexperience to have reduced the resistance
29、of some materials to the effects of soil-borne microorganisms. If used, the type andduration of exposure shall be completely described in the Test Report.7.2 The two types of weathering devices described in the Practices listed below have been used historically prior to evaluationof the microbial su
30、sceptibility of nonmetallic materials by laboratory soil burial. Because of differences in the spectral powerdistributions of the exposure sources as well as the other conditions in the two types of laboratory weathering tests, they mayproduce different test results or require different exposure dur
31、ations for equivalent effects. The two types of exposure cannot beused interchangeably without supporting data that demonstrates equivalency of the exposures for the materials tested.7.2.1 Xenon arc with daylight filters exposures conducted according to Practice G155 Cycle 7A.7.2.2 Fluorescent UVA-
32、340 exposures conducted according to Practice G154 Cycle 1.8. Viability8.1 The viability must be recommended as in 3.34.3 concurrent with the test specimen and exposed consistent with the testspecimen duration and number of test specimens.3 Manual on Presentation of Data and Control Chart Analysis ,
33、 6th ed., Manual 7, American Society for Testing and Materials, 1990.G160 1229. Replicates9.1 A minimum of four replicates are recommended.10. Duration10.1 The exposure period for soil burial, unless otherwise specified, shall be for a minimum of 60 days.NOTE 2The test specimens cannot be removed fo
34、rfrom the soil bed, once they have been buried, until the exposure period has been completed.Disturbing the soil bed in such a manner as removing the test specimens may affect the growth of soil microbes and thus cause inconsistent results. Aseparate set of specimens must be used for each exposure i
35、nterval (for example, a set of replicates for 30, 60, and 90 days as needed).11. Calculation and Interpretation of Results11.1 VisualAt the end of the exposure period, the specimens shall be removed from the soil bed and conditioned accordingto methods appropriate to the material being tested. For v
36、isual evaluation, the material is rinsed under a stream of tap water whilegently rubbing between fingers to remove soil and air-drying at 20C (68F) for minimum amount of time. Alternatively, thematerial may be gently vacuumed or very gently air-brushed.11.2 Microbial staining shall be evaluated as f
37、ollows:Observed Growth or Stain RatingNone 0Trace (less than 10 % coverage) 1Light (10 to 30 % coverage) 2Moderate (30 to 60 % coverage) 3Heavy (60 % to complete coverage) 411.3 Property Changes Physical and mechanical changes such as tensile strength, flexibility, weight loss, or other tests, maybe
38、 performed as described in appropriate ASTM or other test methods. Tests shall be conducted on unexposed and exposedspecimens for the purpose of comparison in determining the extent of microbial degradation of the test material.11.4 Calculate the change in property for each replicate specimen using
39、one of the following equations:Ce, i 5X e, i 2Xo (1)Ce, i 5X e, i 2Xo (1)Ce, i 5Xe, i 2Xf (2)Ce, i 5Xe, i 2Xf (2)where:Ce, i = change in property of each exposed specimenXe, i = measured property of each exposed specimen,XXo = mean of property from initial measurements on unexposed specimens, andXX
40、f = mean of property from measurements on file specimens.11.5 Use the following equation to determine the mean change in property:C 5(i51n Ce, in (3)C 5(i51n Ce, in (3)where:n = number or exposed specimens.11.6 Use the following equation to determine the standard deviation of the change in property:
41、n (4)Sc 5(Ci 2C !2n 21 (4)Sc 5(Ci 2C !2n 21 (4)G160 12312. Report12.1 Report the following information: age of bed, specimen size, number of replicates, performance of viability control, visualstaining in accordance with 9.111.1 and 9.211.2 or property change in accordance with 9.311.3, duration of
42、burial, and any specificmeasurements requested.12.2 If used, report the exposure test and duration and a complete description if the exposure test is different from thoserecommended in Section 7.12.3 Satisfactory or unsatisfactory performance of a material is dependent on the applicable standard for
43、 that material ormethods agreed upon between the investigators.11. Precision and Bias11.1 A precision and bias statement cannot be made at this time.13. Keywords13.1 biodegradeable; biological deterioration; defacement; disfigurement; fungal resistance; fungi; laboratory soil culture;microbial susce
44、ptibility; microbiological deterioration; mildew; mixed microbial innoculum; mold growth; soil environmentASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised tha
45、t 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 revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reappro
46、ved or withdrawn.Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you fee
47、l 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 copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual repr
48、ints (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/).G160 124
