ASTM_G_160_-_12.pdf

Designation:G16012Standard 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,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 anevaluation of a nonmetallic materials microbiological suscep-tibility when in contact with the natural environment of the soilunder use conditions.This practice is intended for use on solidmaterial test specimens that are no larger than approximately 2cm(0.79 in.)thick and 100 cm2(15.5 in.2)or on film formingmaterials such as coatings which may be tested in the form offilms at least 50 by 50 mm(2 by 2 in.)in size.This practicemay be applied to articles that do not spend the majority oftheir service life in soil.1.2 A wide variety of properties may be affected by micro-bial attack depending on material or item characteristics.Standard methods(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 Materials intended for use in soil burial applications areoften subjected to periods of exposure to solar radiation andother elements of weather for some time before they are buried.Because these exposures may alter the ability of a material toresist the effects of soil-borne microorganisms,it is recom-mended that this practice be combined with appropriate envi-ronmental exposures(for example,solar simulating weatheringdevices,the hydrolytic effects of extended aqueous contact,orextraneous nutrients)or fabrication into articles(for example,adhesive bonding of seams)which may promote microbiologi-cal susceptibility during the service life of the material.1.4The 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,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:2G154 Practice for Operating Fluorescent Ultraviolet(UV)Lamp Apparatus for Exposure of Nonmetallic MaterialsG155 Practice for Operating Xenon Arc Light Apparatus forExposure of Non-Metallic Materials3.Significance and Use3.1 These results may be used to compare the susceptibilityof materials when exposed to this test procedure.3.2 Microbiological susceptibility may be reflected by anumber of changes including staining,weight loss,or reductionin tensile or flexural strength.3.3 This practice may be considered an inoculation with amixed culture of fungi and bacteria.4.Soil4.1 Composition Soil 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).4.2 MixingThe soil composition of 4.1 should be preparedby simple mixing and sifting through14-in.mesh screen.4.3 AgingThe 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.NOTE1The soil mixture may be used for sequential tests as long asthe 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 ground1This practice is under the jurisdiction of Committee G03 on Weathering andDurability and is the direct responsibility of Subcommittee G03.04 on BiologicalDeterioration.Current edition approved Nov.1,2012.Published January 2013.Originallyapproved in 1998.Last previous edition approved in 2009 as G160 03(2009).DOI:10.1520/G0160-12.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 limestone to raise the pH or flowers of sulfur to lower the pH.The soil 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.4.5 MoistureThe soil shall be maintained