1、Designation: D6108 18Standard 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, health, and environmental pr
6、actices and deter-mine the applicability of regulatory limitations prior to use.NOTE 1There is no known ISO equivalent to this test method.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Princi
7、ples for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD883 Terminology Relating to PlasticsD4000 C
8、lassification System for Specifying Plastic 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
9、Lumber and Shapes by DisplacementE4 Practices 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 compres
10、sive deformationthe decrease in length 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 g
11、age length along thelongitudinal axis. 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 ruptu
12、re.3.1.4 compressive stress (nominal)the 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 Discuss
13、ionThe expression of compressive stressin 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 j
14、urisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.20 on Plastic Lumber (SectionD20.20.01).Current edition approved June 1, 2018. Published June 2018. Originallyapproved in 1997. Last previous edition approved in 2013 as D6108 13. DOI:10.1520/D6108-18.2
15、For 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.3The last approved version of this historical standard is refe
16、renced onwww.astm.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles o
17、n standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.1.5 compressive stress-strain diagrama diagram inwhich values of compressive str
18、ess are plotted as ordinatesagainst corresponding values 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
19、) to corresponding compressive strain below theproportional 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 originalgag
20、e length.3.1.9 plastic lumber, na manufactured product made 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 lum
21、ber is typically supplied insizes similar to those of traditional 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 made pri-marily from plastic ma
22、terials (filled or unfilled), which is notnecessarily rectangular in cross section.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 force per unit area.3.1.12
23、 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, the term is used todesignate
24、 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 plastic lumber. It isexpresse
25、d 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 failure. Typically a strainval
26、ue 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 testmethod appear in Termino
27、logy 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 materials, therewill be a spec
28、ification 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 D4000 lists the ASTMmaterials s
29、tandards 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 definitevalue. In the case of a m
30、aterial 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 not exhibit a trueyield poin
31、t. 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, accep-tance or rejection und
32、er 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. Apparatus5.1 Testing MachineAny suit
33、able 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 (fixed member), with thiscross-
34、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 shall indicate theload with an
35、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 test specimenat any time d
36、uring 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 requirements for a Class C exten
37、som-eter as defined in Practice E83.5.2.1 The requirements for extensometers cited herein applyto compressometers as well.D6108 1825.2.2 It is acceptable to use compression platen movementto determine compressive displacements of test samples.5.3 Compression PlatensA compression platen for apply-ing
38、 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 micrometers, reading to 0.01
39、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 ends so that smooth, flat p
40、arallel 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, parallel ends shall not b
41、e 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 rod and whose height is twice
42、 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 ConditioningCondition the test specimens at 73.4 63.6F (23 6 2C) an
43、d 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 ConditionsConduct tests in
44、the Standard Labora-tory 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 Speed of testing shall be th
45、e 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 standard speed of testing shall resu
46、lt 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 atseveral points along its lengt
47、h. 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 for accurate measurement of the
48、 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 with the center line of the pl
49、atens 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 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
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