1、Designation: G 160 03 (Reapproved 2009)Standard Practice forEvaluating Microbial Susceptibility of Nonmetallic MaterialsBy Laboratory Soil Burial1This standard is issued under the fixed designation G 160; the number immediately following the designation indicates the year oforiginal adoption or, in
2、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 anevaluation of a nonmetallic m
3、aterials microbiological suscep-tibility when in contact with the natural environment of thesoil. This practice is intended for use on solid material testspecimens that are no larger than approximately 2 cm (34 in.)thick and 100 cm2(20 in.2) or on film forming materials suchas coatings which may be
4、tested in the form of films at least 50by 50 mm (2 by 2 in.) in size. This practice may be applied toarticles that do not spend the majority of their service life insoil.1.2 A wide variety of properties may be affected by micro-bial attack depending on material or item characteristics.Standard metho
5、ds (where available) should be used for eachdifferent property to be evaluated. This practice does notattempt to enumerate all of the possible properties of interestnor specify the most appropriate test for those properties. Testmethods must, however, be appropriate to the material beingtested.1.3 I
6、t is recommended that this practice be combined withappropriate environmental exposures (for example, sunlightsimulating weathering devices, the hydrolytic effects of ex-tended aqueous contact, or extraneous nutrients) or fabricationinto articles (for example, adhesive bonding of seams) whichmay pro
7、mote microbiological susceptibility during the servicelife of the material.1.4 The values stated in SI units are to be regarded asstandard. The values given in parentheses are provided forinformation purposes only.1.5 This standard does not purport to address all of thesafety concerns, if any, assoc
8、iated 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. Significance and Use2.1 These results may be used to compare the susceptibilityof materials when e
9、xposed to this test procedure.2.2 Microbiological susceptibility may be reflected by anumber of changes including staining, weight loss, or reductionin tensile or flexural strength.2.3 This practice may be considered an inoculation with amixed culture of fungi and bacteria.3. Soil3.1 Composition Soi
10、l shall be composed of equal parts offertile topsoil (soil with a high clay content should not beused), well-rotted and shredded horse manure, and coarse sand(10 to 40 mesh).3.2 MixingThe soil composition of 3.1 should be pre-pared by simple mixing and sifting through14-in. mesh screen.3.3 AgingThe
11、mixture is aged for three months andresifted twice at four-week intervals during the three months.After three months, a viability control of untreated cotton cloth,400 to 475 g/m2(12 to 14 oz/yd2), buried in the soil shall havea tensile strength loss of at least 50 % after five days.NOTE 1The soil m
12、ixture may be used for sequential tests as long asthe cotton cloth control degrades within the specified time period.3.4 pHThe soil shall have a pH between 6.5 to 7.5,checked periodically, and maintained by the addition of groundlimestone to raise the pH or flowers of sulfur to lower the pH.The soil
13、 pH may be taken by dispersing 1 weight part soil in 20parts of water, shaking or stirring, then allowing the mix tosettle for 1 h. The pH is measured with indicator paper,electrodes, or by titration.3.5 MoistureThe soil shall be maintained at between 20and 30 % moisture, based on the dry weight of
14、the soil. (Thepercent moisture is calculated by weighing approximately 50mL of a representative portion and taking the portion toconstant weight by placing the soil in an oven at a temperatureof 101 to 106C.) Water lost during use as a result ofevaporation shall be replaced without deforming the soi
15、l bed. Ifthe surrounding atmosphere is maintained at 85 to 95 %relative humidity, this loss is negligible, however, the moisturelevel should be periodically measured.1This practice is under the jurisdiction of Committee G03 on Weathering andDurability and is the direct responsibility of Subcommittee
16、 G03.04 on BiologicalDeterioration.Current edition approved June 1, 2009. Published July 2009. Originally approvedin 1998. Last previous edition approved in 2003 as G 160 03.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Apparatu
17、s4.1 Soil Container The container shall be any material ofsuitable mechanical strength and chemical/microbial resistanceand, if porous, shall be lined with impermeable material. Itshall be of any size that is convenient to handle and having adepth of at least 12.7 cm (5 in.).4.2 External Environment
18、An apparatus capable of main-taining a temperature of 30 6 2C (86 6 3.6F) and a relativehumidity to 85 to 95 %, into which the assembled container isinserted, is necessary. An incubator or controlled tropicalchamber is adequate.5. Test Specimens5.1 Completely fabricated parts or sections cut from fa
19、bri-cated parts may be used as test specimens. The simplestspecimen may be a 50- by 50-mm (2- by 2-in.) piece, a 50-mm(2-in.) diameter piece, or a piece (rod or tubing) at least 76 mm(3 in.) long cut from the material to be tested.5.2 Film-forming materials such as coatings may be testedin the form
20、of films at least 50 by 50 mm (2 by 2 in.) in size.Such films may be prepared by casting on glass and strippingafter cure or by impregnating (completely covering) filter paperor ignited glass fabric.5.3 For visual evaluation, a minimum of three test speci-mens shall be used.5.4 In devising a test pr
21、ogram intended to reveal quantita-tive changes occurring during and after exposure, an adequatenumber of specimens should be evaluated to establish a validvalue for the original property. For example, if five replicatetest specimens are required to establish a tensile strength of afilm material, at
22、least that number of test specimens shall beremoved and tested for each exposure period. It is to beexpected that values of physical or mechanical properties atvarious stages of fungal attack will be variable. The ASTMManual 72may be used as a guide.6. Viability6.1 The viability must be recommended
23、as in 3.3 concurrentwith the test specimen and exposed consistent with the testspecimen duration and number of test specimens.7. Replicates7.1 A minimum of four replicates are recommended.8. Duration8.1 The exposure period for soil burial, unless otherwisespecified, shall be for a minimum of 60 days
24、.NOTE 2The test specimens cannot be removed for the soil bed, oncethey have been buried, until the exposure period has been completed.Disturbing the soil bed in such a manner as removing the test specimensmay affect the growth of soil microbes and thus cause inconsistent results.A separate set of sp
25、ecimens must be used for each exposure interval (forexample, a set of replicates for 30, 60, and 90 days as needed).9. Calculation and Interpretation of Results9.1 VisualAt the end of the exposure period, the speci-mens shall be removed from the soil bed and conditionedaccording to methods appropria
26、te to the material being tested.For visual evaluation, the material is rinsed under a stream oftap water while gently rubbing between fingers to remove soiland air-drying at 20C (68F) for minimum amount of time.Alternatively, the material may be gently vacuumed or verygently air-brushed.9.2 Microbia
27、l staining shall be evaluated as follows: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) 49.3 Property Changes Physical and mechanical changessuch as tensile strength, flexibility, we
28、ight loss, or other tests,may be performed as described in appropriate ASTM or othertest methods. Tests shall be conducted on unexposed andexposed specimens for the purpose of comparison in determin-ing the extent of microbial degradation of the test material.9.4 Calculate the change in property for
29、 each replicatespecimen using one of the following equations:Ce, i5Xe, i2 Xo(1)Ce, i5 Xe, i2 Xf(2)where:Xe, i= measured property of each exposed specimen,Xo= mean of property from initial measurements onunexposed specimens, andXf= mean of property from measurements on file speci-mens.9.5 Use the fol
30、lowing equation to determine the meanchange in property:C 5(i 5 1nCe, in(3)where:n = number or exposed specimens.9.6 Use the following equation to determine the standarddeviation of the change in property:n (4)Sc5(Ci2C !2n 2 110. Report10.1 Report the following information: age of bed, speci-men siz
31、e, number of replicates, performance of viabilitycontrol, visual staining in accordance with 9.1 and 9.2 orproperty change in accordance with 9.3, duration of burial, andany specific measurements requested.10.2 Satisfactory or unsatisfactory performance of a mate-rial is dependent on the applicable
32、standard for that material ormethods agreed upon between the investigators.2Manual on Presentation of Data and Control Chart Analysis , 6th ed., Manual7, American Society for Testing and Materials, 1990.G 160 03 (2009)211. Precision and Bias11.1 A precision and bias statement cannot be made at thist
33、ime.12. Keywords12.1 biodegradeable; biological deterioration; defacement;disfigurement; fungal resistance; fungi; laboratory soil culture;microbial susceptibility; microbiological deterioration; mil-dew; mixed microbial innoculum; mold growth; soilenvironmentASTM International takes no position res
34、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
35、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
36、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
37、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).G 160 03 (2009)3
