1、Designation: D7568 12Standard Specification forPolyethylene-Based Structural-Grade Plastic Lumber forOutdoor Applications1This standard is issued under the fixed designation D7568; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th
2、e 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 specification covers a type of plastic lumberproduct, defined as polyethylene-based structural-grade pl
3、asticlumber (SGPL), for use as main framing members, includingjoists, stringers, beams, columns; and secondary framing mem-bers, including planking, posts and bracing; in outdoor struc-tures such as decks, boardwalks, docks, and platforms.1.2 This specification is applicable to solid, rectangularSGP
4、L products where polyethylene resin (non cross-linked) isthe continuous phase and is at least 50 % of the product (byweight).1.3 This specification is not applicable to plastic lumberproducts containing cellulosic materials as additives, fillers orfiber reinforcements.1.4 SGPLproducts covered by thi
5、s specification shall not beused as tensile members.1.5 SGPL products are produced using several differentmanufacturing processes. These processes utilize a number ofpolyethylene resin material systems that include varying pro-portions of fillers, fiber reinforcements, and other chemicaladditives.1.
6、6 Due to thermodynamic effects that result in outer-surface densification during manufacture, SGPL products aretypically non-homogeneous in the cross-section. This standarddoes not address materials that have been modified from theiroriginal cross-section.1.6.1 The cross-section non-homogeneity is a
7、ddressed inthe material property assessments in this document only forapplications in which the product cross-section is not modifiedby cutting, notching, or drilling. For products modified in thismanner, additional engineering considerations are required andthey are beyond the scope of this documen
8、t.1.7 For purposes of this standard, an SGPL product is aspecific combination of polyethylene resin, together withfillers, reinforcements, and additives. Each formulation is to beidentified as a distinct and different product, to be tested andevaluated separately.1.8 Diverse and multiple combination
9、s of both virgin andrecycled polyethylene material systems are permitted in themanufacture of SGPL products.1.9 Fiber reinforcements used in SGPL include manufac-tured materials such as fiberglass (chopped or continuous),carbon, aramid and other polymeric materials.1.10 A wide variety of chemical ad
10、ditives are typicallyadded to SGPL formulations. Examples include colorants,chemical foaming agents, ultraviolet stabilizers, fire retardants,lubricants, anti-static products, heat stabilizers, and couplingagents.1.11 Diverse types and combinations of filler systems arepermitted in the manufacturing
11、 of SGPL products. Fillers thatcause the product to fail the requirements of 6.13 are notpermitted in the manufacturing of SGPL products.1.12 In order for a product to be classified as SGPL, it mustmeet the minimum stress and modulus criteria consistent withthe specific product as marked, and additi
12、onally the propertiesspecified in Section 6 of this specification.1.13 This specification pertains to SGPL where any rein-forcement is uniformly distributed within the product. Whenreinforcement is not uniformly distributed, the engineeringissues become substantially more complex. For this reason,su
13、ch products are not covered in this document.1.14 Products that fail at strains of less than 0.02 (2 %)when tested in flexure in accordance with 6.6 are not compat-ible with the underlying assumptions of Annex A1 and arebeyond the scope of this standard (see Note 1).NOTE 1Calculation of time-depende
14、nt properties in Annex A1 isbased on the assumption that the product does not fail in a brittle manner.The 2 % strain limit was selected based on the judgment of the task groupmembers that created Annex A1.1.15 This specification addresses issues relevant to a buy-ers requirements for SGPL products
15、and has therefore beendeveloped in the format of a procurement specification.1.16 Criteria for design are included as part of this specifi-cation for SGPL products.1.17 Use of SGPL members in application will typicallyrequire the design of structural connections. Connection designbetween SGPL member
16、s falls outside the scope of this stan-dard.1This is under the jurisdiction of ASTM Committee D20 on Plastics and is thedirect responsibility of Subcommittee D20.20 on Plastic Lumber.Current edition approved June 1, 2012. Published September 2012.DOI:10.1520/D756812.1Copyright ASTM International, 10
17、0 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.1.18 The values are stated in inch-pound units, as these arecurrently the most common units used by the US constructionindustry. Equivalent SI units are indicated in parentheses.1.19 This standard does not purport to a
18、ddress 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.NOTE 2There is no known ISO equivalent to this Standar
19、d.2. Referenced Documents2.1 The following documents of the issue in effect on thedate of product purchase form a part of this specification to theextent referenced herein:2.2 ASTM Standards:2D883 Terminology Relating to PlasticsD2344/D2344M Test Method for Short-Beam Strength ofPolymer Matrix Compo
20、site Materials and Their LaminatesD2915 Practice for Sampling and Data-Analysis for Struc-tural Wood and Wood-Based ProductsD6108 Test Method for Compressive Properties of PlasticLumber and ShapesD6109 Test Methods for Flexural Properties of Unrein-forced and Reinforced Plastic Lumber and Related Pr
21、od-uctsD6112 Test Methods for Compressive and Flexural Creepand Creep-Rupture of Plastic Lumber and ShapesD6341 Test Method for Determination of the Linear Coef-ficient ofThermal Expansion of Plastic Lumber and PlasticLumber Shapes Between 30 and 140F (34.4 and 60C)D6662 Specification for Polyolefin
22、-Based Plastic LumberDecking BoardsD7032 Specification for Establishing Performance Ratingsfor Wood-Plastic Composite Deck Boards and GuardrailSystems (Guards or Handrails)E84 Test Method for Surface Burning Characteristics ofBuilding Materials2.3 Other Documents:ASCE 7 Minimum Design Loads for Buil
23、dings and OtherStructures33. Terminology3.1 Definitions of TermsFor definitions of terms used inthis specification associated with plastics issues refer to theterminology contained in Terminology D883.3.2 Definitions:3.2.1 plastic lumber, na manufactured product made pri-marily from plastic material
24、s (filled or unfilled) which isgenerally rectangular in cross-section and is typically suppliedin sizes that correspond to traditional lumber board anddimensional lumber sizes (Terminology D883).3.2.2 resin, na solid or pseudo solid organic materialoften of high molecular weight, which exhibits a te
25、ndency toflow when subjected to stress, usually has a softening ormelting range, and usually fractures conchoidally (Terminol-ogy D883).3.2.2.1 DiscussionIn a broad sense, the term is used todesignate any polymer that is a basic material for plastics.3.3 Definitions of Terms Specific to This Standar
26、d:3.3.1 bulge, nconvex distortion (away from the center ofthe cross-section) of the face of the product from a straight linedrawn from edge to edge across the width.3.3.2 crook, ndistortion of the product in which there is adeviation in a direction perpendicular to the edge from astraight line from
27、end to end along the length.3.3.3 cup, nconcave distortion (towards the center of thecross-section) of the face of the product from a straight linedrawn from edge to edge across the width.3.3.4 edge, nthe side of a rectangular-shaped productcorresponding to the thickness.3.3.5 face, nthe side of a p
28、roduct corresponding to thewidth.3.3.6 reinforcement, na material added to the thermoplas-tic resin to improve its mechanical properties.3.3.7 self-supporting specimen, na specimen that remainsin place by its own structural characteristics both before andduring a fire test.3.3.8 structural grade pla
29、stic lumber, na solid, rectangu-lar reinforced thermoplastic composite lumber product manu-factured for load-bearing applications such as joists, beams, orcolumns in outdoor structures.3.3.9 test set, na full complement of test specimensrequired for a specific assessment.3.3.9.1 DiscussionAs an exam
30、ple, a test set for flexuralproperties (see 6.6.3) requires 28 test specimens.3.3.10 thickness, nthe lesser dimension of the cross-sectional profile of a rectangular-shaped product.3.3.11 width, nthe greater dimension of the cross-sectional profile of a rectangular-shaped product, or the dimen-sion
31、of the cross-sectional profile of a square product.4. Ordering Information4.1 The information contained in this specification is in-tended to be helpful to producers, distributors, regulatoryagencies and users including designers, architects, and engi-neers. The information will also promote underst
32、anding be-tween purchasers and sellers. The purchaser shall state whetherthis specification is to be used, select the preferred optionspermitted herein, and include the allowable design informationin the invitation to bid and purchase order from the following:4.1.1 Title, number and date of this spe
33、cification,4.1.2 Minimum allowable bending stress and apparentbending stiffness,4.1.3 Percent recycled content (if requested),4.1.4 Flame spread index,4.1.5 Color,4.1.6 Quantity in lineal feet,4.1.7 Cut length,4.1.8 Cross-sectional dimensions,4.1.9 Packing requirements,2For referenced ASTM standards
34、, 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.3Available from American Society of Civil Engineers (ASCE), 1801 AlexanderBell Dr., Reston,
35、 VA 20191, http:/www.asce.org.D7568 1224.1.10 Palletization, if required,4.1.11 Marking, if other than specified.5. Dimensions and Permissible Variations5.1 It is permissible to produce SGPL either in sizes that aresimilar to the standard dimensions of the wood industry, or toother dimensions design
36、ated by manufacturers or buyers. Thisspecification does not limit the dimensional range of produc-tion.5.2 Use of a licensed Professional Engineer is recom-mended for designing and selecting SGPL products in accor-dance with this specification.5.3 ThicknessUnless otherwise specified in 4.1.8, produc
37、tthickness tolerance shall be:For members less than 2 in. in nominal thickness thetolerance on thickness shall be +316 /-116 .Nominal (in.) Actual (in.) Tolerance (in.)2112 +316 /-1163212 +316 /-1164312 +316 /-3325412 +316 /-3326512 +316 /-18For members greater than 6 in. in nominal thickness thetol
38、erance on thickness shall be +316 /-18 inch.5.4 WidthUnless otherwise specified in 4.1.8, productwidth shall be:For members less than 3 in. in nominal width the toleranceon width shall be +316 /116 inch.Nominal (in.) Actual (in.) Tolerance(in.)3212 +316 /-1164312 +316 /-3326512 +316 /-3328714 +316 /
39、-1810 914 +316 /-1812 1114 +14 /-532For members greater than 12 in. in nominal width thetolerance on width shall be +14 /-532 inch.5.5 LengthUnless otherwise specified in 4.1.7, productsup to 20 ft shall have tolerances of 612 inch. Over 20 feet thetolerances shall be 612-in. per 20-ft of length or
40、fractionthereof. Measurement of lengths shall be made at 23 6 2C(73.4 6 4F) and relative humidity of 50 6 5%.5.6 Flatness ToleranceProducts shall be flat with a maxi-mum cup or bulge in the face limited to the tolerances in Table1 and Table 2. Linear interpolation of the values is acceptablefor dime
41、nsions other than listed.TABLE 1 Cup or Bulge Tolerances Relative to Nominal Width(2x)Face Width, in. #4 in. 6 in. 8 in. 10 in. 12 in.Tolerance (6)116 in.332 in.18 in.316 in.14 in.TABLE 2 Cup or Bulge Tolerances Relative to Nominal Size(square)Size, in. #4 in. 6 in. 8 in. 10 in. 12 in.Tolerance (6)3
42、32 in.18 in.316 in.14 in.14 in.5.7 SquarenessUnless a specially shaped member isspecified, the cross-section of all structural-grade plastic lum-ber products shall be perpendicular (that is, 90 degree anglefrom face to edge of a square or rectangular shape and suitedfor the intended purpose).5.8 Cro
43、okCrook shall conform to the tolerances in Table3. Linear interpolation of the values is acceptable for dimen-sions other than listed.6. Performance Requirements6.1 Load Combinations: Plastic members subject to mul-tiple load types shall be checked for all applicable loadcombinations. Load factors a
44、nd load reductions shall bedetermined in accordance with the applicable code orASCE 7.All applicable load combinations shall be evaluated to deter-mine the critical load combination to be used in design.NOTE 3Application of load duration factors to load combinations inwhich each load has a different
45、 associated duration is a complex processand varies depending on whether the design engineer is using allowablestress design (ASD) or load and resistance factor design (LRFD) meth-odology. A conservative design approach applies the load duration factorequal to the longest duration in the applicable
46、load combination. Morerefined approaches for specific applications can be found in the technicalliterature.6.2 Design Properties:6.2.1 All members shall be designed such that for all loadcombinations:fa#Fn8 3 CD(1)where:fa= total applied stress in each combination (psi)Fn8 = allowable stress as calc
47、ulated in 6.6.3.2, 6.7.2,6.8.2.1, 6.8.3.1,or6.9.3.2 (psi)CD= Load Duration Factor for the material and consideredload duration. Derivation of CDis explained inAnnex A2.6.3 Interpolation of Properties:6.3.1 Interpolation of mechanical properties of a SGPLproduct from test data from the same product a
48、t other widthdimensions is permitted if the test results verify a logicalprogression of properties and the following conditions are met:6.3.1.1 All specimens have the same thickness and materialcomposition.6.3.1.2 Three or more test sets are performed on specimenswith varying width.6.3.1.3 At least
49、one test set is performed on specimens witha width greater than that of the product whose properties arebeing interpolated.6.3.1.4 At least one test set is performed on specimens witha width less than that of the product whose properties are beinginterpolated.6.4 Creep Rupture:TABLE 3 Crook Tolerances Relative to Nominal Length andWidthLength in Feet #4 in. Width 6 in. Width 8 in. Width 10 in. Width 12 in. Width4-638 in.14 in.316 in.316 in.316 in.812 in.12 in.38 in.38 in.38 in.1034 in.5
