1、Designation: D6108 13Standard Test Method forCompressive Properties of Plastic Lumber and Shapes1This standard is issued under the fixed designation D6108; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of the me-chanical properties of plastic lumber and shapes, when theentire cross-section i
3、s loaded in compression at relatively lowuniform rates of straining or loading. Test specimens in the“as-manufactured” form are employed. As such, this is a testmethod for evaluating the properties of plastic lumber orshapes as a product and not a material property test method.1.2 Plastic lumber and
4、 plastic shapes are currently madepredominantly with recycled plastics. However, this testmethod would also be applicable to similar manufacturedplastic products made from virgin resins, or where the productis non-homogenous in the cross-section.1.3 The values stated in inch-pound units are to be re
5、gardedas the standard. The values given in parentheses are forinformation only.1.4 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 dete
6、rmine the applica-bility of regulatory limitations prior to use.NOTE 1There is no known ISO equivalent to this test method.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD883 Terminology Relating to PlasticsD4000 Classification System for Specifying Pla
7、stic Materi-alsD5033 Guide for Development ofASTM Standards Relatingto Recycling and Use of Recycled Plastics (Withdrawn2007)3D5947 Test Methods for Physical Dimensions of SolidPlastics SpecimensD6111 Test Method for Bulk Density And Specific Gravityof Plastic Lumber and Shapes by DisplacementE4 Pra
8、ctices for Force Verification of Testing MachinesE83 Practice for Verification and Classification of Exten-someter SystemsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions:3.1.1 compressive deformationthe decrease in length
9、pro-duced in the gage length of the test specimen by a compressiveload. It is expressed in units of length.3.1.2 compressive strainthe ratio of compressive defor-mation to the gage length of the test specimen, that is, thechange in length per unit of original gage length along thelongitudinal axis.
10、It is expressed as a dimensionless ratio.3.1.3 compressive strengththe maximum compressivestress (nominal) carried by a test specimen during a compres-sion test. It may or may not be the compressive stress(nominal) carried by the specimen at the moment of rupture.3.1.4 compressive stress (nominal)th
11、e compressive loadper unit area of minimum (or effective as calculated inaccordance with Test Method D6111) original cross sectionwithin the gage boundaries, carried by the test specimen at anygiven moment. It is expressed in force per unit area.3.1.4.1 DiscussionThe expression of compressive stress
12、in terms of the minimum original cross section is almostuniversally used. Under some circumstances the compressivestress has been expressed per unit of prevailing cross section.This stress is called the “true compressive stress”.1This test method is under the jurisdiction of ASTM Committee D20 on Pl
13、asticsand is the direct responsibility of Subcommittee D20.20 on Plastic Lumber (SectionD20.20.01).Current edition approved June 1, 2013. Published June 2013. Originallyapproved in 1997. Last previous edition approved in 2009 as D6108 09. DOI:10.1520/D6108-13.2For referenced ASTM standards, visit th
14、e 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.3The last approved version of this historical standard is referenced onwww.astm.org.*A Summary of Cha
15、nges section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.5 compressive stress-strain diagrama diagram inwhich values of compressive stress are plotted as ordinatesagainst corresponding values
16、 of compressive strain as abscis-sas.3.1.6 compressive yield pointthe first point on the stress-strain diagram at which an increase in strain occurs without anincrease in stress.3.1.7 modulus of elasticitythe ratio of compressive stress(nominal) to corresponding compressive strain below theproportio
17、nal limit of a material. It is expressed in force per unitarea based on the effective/average initial cross-sectional area.3.1.8 percent compressive strainthe compressive defor-mation of a test specimen expressed as a percent of the originalgage length.3.1.9 plastic lumber, na manufactured product m
18、ade pri-marily from plastic materials (filled or unfilled), typically usedas a building material for purposes similar to those of tradi-tional lumber, which is usually rectangular in cross-section.(Terminology D883)3.1.9.1 DiscussionPlastic lumber is typically supplied insizes similar to those of tr
19、aditional lumber board, timber anddimension lumber; however the tolerances for plastic lumberand for traditional lumber are not necessarily the same.(Terminology D883)3.1.10 plastic shape, na manufactured product composedof more than 50 weight percent resin, and in which the productgenerally is not
20、rectangular in cross-section, may be filled orunfilled, and may be composed of single or multiple resinblends.3.1.11 proportional limitthe greatest compressive stressthat a material is capable of sustaining without any deviationfrom proportionality of stress to strain (Hookes law). It isexpressed in
21、 force per unit area.3.1.12 resin, na solid or pseudosolid organic materialoften of high molecular weight, which exhibits a tendency toflow when subjected to stress, usually has a softening ormelting range, and usually fractures conchoidally. (Terminol-ogy D883)3.1.12.1 DiscussionIn a broad sense, t
22、he term is used todesignate any polymer that is a basic material for plastics.3.1.13 secant modulusthe ratio of the compressive stress(nominal) to the corresponding value of compressive strain onthe stress-strain diagram at a specified value of strain, typicallyone percent strain (0.01 mm/mm) for pl
23、astic lumber. It isexpressed in force per unit area based on the effective initialcross-sectional area.3.1.14 stress at a given strainthe stress on the stress-straincurve at a specified value of strain.3.1.14.1 DiscussionThe stress at a given strain should notbe taken as the ultimate strength at fai
24、lure. Typically a strainvalue of 3 % or 0.03 mm/mm is used for plastic lumber. Theultimate strength, or the maximum value of stress on thestress-strain diagram, can be higher for plastic lumber occur-ring at values of strain much greater than 3 %.3.2 Additional definition of terms applying to this t
25、estmethod appear in Terminology D883 and Guide D5033.4. Significance and Use4.1 Compression tests provide information about the com-pressive properties of plastic lumber and shapes when theseproducts are used under conditions approximating those underwhich the tests are made. In the case of some mat
26、erials, therewill be a specification that requires the use of this test method,but with some procedural modifications that take precedencewhen adhering to the specification. Therefore, it is advisable torefer to that material specification before using this testmethod. Table 1 in Classification D400
27、0 lists the ASTMmaterials standards that currently exist.4.2 Compressive properties include modulus of elasticity,secant modulus, compressive strength, and stress at a givenstrain. In the case of a material that fails in compression by ashattering fracture, the compressive strength has a very defini
28、tevalue. In the case of a material that does not fail in compressionby a shattering fracture nor exhibits a compressive yield point,the compressive strength is an arbitrary one depending uponthe degree of distortion that is regarded as indicating completefailure. Many plastic lumber materials will n
29、ot exhibit a trueyield point. Compressive strength can have no real meaning insuch cases. For plastic lumber, the stress at a given strain of3 % (0.03 in./in. (mm/mm) is typically used.4.3 Compression tests provide a standard method of obtain-ing data for research and development, quality control, a
30、ccep-tance or rejection under specifications, and special purposes.The tests cannot be considered significant for engineeringdesign in applications differing widely from the load-time scaleof the standard test. Such applications require additional testssuch as impact, creep, and fatigue.5. Apparatus
31、5.1 Testing MachineAny suitable testing machine capableof control of constant-rate-of-crosshead movement and com-prising essentially the following:5.1.1 Drive MechanismA drive mechanism for impartingto the cross-head movable member, a uniform, controlled rateof movement with respect to the base (fix
32、ed member), with thiscross-head rate to be regulated as specified in Section 9.5.1.2 Load IndicatorA load-indicating mechanism ca-pable of showing the total compressive load carried by the testspecimen. The mechanism shall be essentially free frominertia-lag at the specified rate of testing and shal
33、l indicate theload with an accuracy of 61 % of the maximum indicatedvalue of the test (load). The accuracy of the testing machineshall be verified at least once a year in accordance withPractices E4.5.2 CompressometerA suitable instrument for determin-ing the distance between two fixed points on the
34、 test specimenat any time during the test. It is desirable that this instrumentautomatically record this distance (or any change in it) as afunction of the load on the test specimen. The instrument shallbe essentially free of inertia-lag at the specified rate of loadingand shall conform to the requi
35、rements for a Class C extensom-eter as defined in Practice E83.D6108 1325.2.1 The requirements for extensometers cited herein applyto compressometers as well.5.2.2 It is acceptable to use compression platen movementto determine compressive displacements of test samples.5.3 Compression PlatensA compr
36、ession platen for apply-ing the load to the test specimen. Parallel platens shall be usedto apply the load to an unconfined type specimen. One of thecompression platens shall be self aligning so that it will bepossible to apply the load evenly over the face of the specimen.5.4 MicrometersSuitable mi
37、crometers, reading to 0.01 in.for measuring the width, thickness, and length of the speci-mens.6. Test Specimens6.1 Test specimens for determining compressive propertiesof plastic lumber and shapes shall be cut from the “asmanufactured” profile. Great care shall be taken in cutting andmachining the
38、ends so that smooth, flat parallel surfaces andsharp, clean edges result and are within 1/300 (0.0033) of thespecimen length perpendicular to the long axis of the speci-men. Plastic lumber is generally nonuniform through thecross-section; machining operations other than those requiredto provide flat
39、, parallel ends shall not be carried out.6.2 The standard test specimen, except as indicated in 6.3 to6.4, shall be in the form of a right cylinder or prism whoseheight is twice its minimum width or diameter.6.3 For rod material, the test specimen shall have a diameterequal to the diameter of the ro
40、d and whose height is twice itsdiameter.6.4 When testing hollow profiles, the test specimen shallhave a length equal to twice its minimum cross sectionaldimension.7. Number of Test Specimens7.1 Five specimens shall be tested for each sample.8. Conditioning8.1 Conditioning Condition the test specimen
41、s at 73.4 63.6F (23 6 2C) and 50 6 5 % relative humidity for not lessthan 40 h prior to testing in accordance with Procedure A ofPractice D618, unless otherwise specified by the customer orproduct specification. In cases of disagreement, the tolerancesshall be 61C and 62 % relative humidity.8.2 Test
42、 Conditions Conduct tests in the Standard Labo-ratory Atmosphere of 73.4 6 3.6F (23 6 2C) and 50 6 5%relative humidity, unless otherwise specified by the customeror product specification. In cases of disagreement, the toler-ances shall be 61.8F (61C) and 62 % relative humidity.9. Speed of Testing9.1
43、 Speed of testing shall be the relative rate of motion ofthe compression platens during the test. It is acceptable to userate of motion of the driven platen when the machine is runningidle if it can be shown that the resulting speed of testing iswithin the limits of variation allowed.9.2 The standar
44、d speed of testing shall result in a strain rateof 0.03 6 0.003 in./in./min (mm/mm/min). At this speed atypical compression test on plastic lumber is expected to last 1to 5 min.10. Procedure10.1 Measure the width and thickness or diameter of thespecimen to a precision of1%ofthemeasured dimension ats
45、everal points along its length. Calculate and record theminimum value of the cross-sectional area. Measure the lengthof the specimen at several points and record the value (see TestMethods D5947 for additional information).10.1.1 For test specimens that have some characteristic thatdoes not allow fo
46、r accurate measurement of the cross-sectionalarea in accordance with 10.1, it is acceptable to use theeffective cross-sectional area as determined from Test MethodD6111.10.2 Place the test specimen between the surfaces of thecompression platens, taking care to align the center line of itslong axis w
47、ith the center line of the platens to ensure that theends of the specimen are parallel with the surface of theplatens.Adjust the crosshead of the testing machine until it justcontacts the top of the compression platen.10.3 If only compressive strength or stress at a given strainare desired, proceed
48、as follows:10.3.1 Set the speed control so that it results in a strain rateof 0.03 6 0.003 in./in./min (mm/mm/min) and start the test.10.3.2 Record the maximum load carried by the specimenduring the test (usually this will be the load at the moment ofrupture). Or, record the value of load when the s
49、pecified valueof strain (3 % or 0.03 in./in. (mm/mm) for plastic lumber) isreached.10.4 If stress-strain data are desired, proceed as follows:10.4.1 Attach the compressometer if being used.10.4.2 Set the speed control so that it results in a strain rateof 0.03 6 0.003 in./in./min (mm/mm/min) and start the test.10.4.3 Record loads and corresponding compressive strainat appropriate intervals of strain or, if the test machine isequipped with an automatic recording device, record thecomplete load-deformation curve.10.4.4 Continue the test until the sp
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