1、Designation: D7568 13D7568 17Standard 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 revi
2、sion, 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. Scope Scope*1.1 This specification covers a type of plastic lumber product, defined as polyethylene-based str
3、uctural-grade plastic lumber(SGPL), for use as main framing members, including joists, stringers, beams, columns; and secondary framing members, includingplanking, posts and bracing; in outdoor structures such as decks, boardwalks, docks, and platforms.1.2 This specification is applicable to solid,
4、rectangular SGPL products where polyethylene resin (non cross-linked) is thecontinuous phase and is at least 50 % of the product (by weight).1.3 This specification is not applicable to plastic lumber products containing cellulosic materials as additives, fillers or fiberreinforcements.1.4 SGPL produ
5、cts covered by this specification shall not be used as tensile members.1.5 SGPL products are produced using several different manufacturing processes. These processes utilize a number ofpolyethylene resin material systems that include varying proportions of fillers, fiber reinforcements, and other c
6、hemical additives.1.6 Due to thermodynamic effects that result in outer-surface densification during manufacture, SGPL products are typicallynon-homogeneous in the cross-section. This standard does not address materials that have been modified from their originalcross-section.1.6.1 The cross-section
7、 non-homogeneity is addressed in the material property assessments in this document only forapplications in which the product cross-section is not modified by cutting, notching, or drilling. For products modified in thismanner, additional engineering considerations are required and they are beyond t
8、he scope of this document.1.7 For purposes of this standard, an SGPL product is a specific combination of polyethylene resin, together with fillers,reinforcements, and additives. Each formulation is to be identified as a distinct and different product, to be tested and evaluatedseparately.1.8 Divers
9、e and multiple combinations of both virgin and recycled polyethylene material systems are permitted in themanufacture of SGPL products.1.9 Fiber reinforcements used in SGPL include manufactured materials such as fiberglass (chopped or continuous), carbon,aramid and other polymeric materials.1.10 A w
10、ide variety of chemical additives are typically added to SGPL formulations. Examples include colorants, chemicalfoaming agents, ultraviolet stabilizers, fire retardants, lubricants, anti-static products, heat stabilizers, and coupling agents.1.11 Diverse types and combinations of filler systems are
11、permitted in the manufacturing of SGPL products. Fillers that causethe product to fail the requirements of 6.13 are not permitted in the manufacturing of SGPL products.1.12 In order for a product to be classified as SGPL, it must meet the minimum stress and modulus criteria consistent with thespecif
12、ic product as marked, and additionally the properties specified in Section 6 of this specification.1.13 This specification pertains to SGPL where any reinforcement is uniformly distributed within the product. Whenreinforcement is not uniformly distributed, the engineering issues become substantially
13、 more complex. For this reason, suchproducts 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 compatible withthe underlying assumptions of Annex A1 and are beyond the scope of this standard (see Note 1).
14、1 This specification is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.20 on Plastic Lumber.Current edition approved June 1, 2013March 1, 2017. Published June 2013March 2017. Originally approved in 2012. Last previous edition approved in
15、 20122013 as D7568 12. DOI:10.1520/D756813.13. DOI:10.1520/D756817.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict a
16、ll changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,
17、100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1NOTE 1Calculation of time-dependent properties in Annex A1 is based 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 group membe
18、rs that created Annex A1.1.15 This specification addresses issues relevant to a buyers requirements for SGPLproducts and has therefore been developedin the format of a procurement specification.1.16 Criteria for design are included as part of this specification for SGPL products.1.17 Use of SGPL mem
19、bers in application will typically require the design of structural connections. Connection designbetween SGPL members falls outside the scope of this standard.1.18 The values are stated in inch-pound units, as these are currently the most common units used by the US constructionindustry. Equivalent
20、 SI units are indicated in parentheses.1.19 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatoryli
21、mitations prior to use.NOTE 2There is no known ISO equivalent to this Standard.2. Referenced Documents2.1 The following documents of the issue in effect on the date of product purchase form a part of this specification to the extentreferenced herein:2.2 ASTM Standards:2D883 Terminology Relating to P
22、lasticsD2344/D2344M Test Method for Short-Beam Strength of Polymer Matrix Composite Materials and Their LaminatesD2915 Practice for Sampling and Data-Analysis for Structural Wood and Wood-Based ProductsD6108 Test Method for Compressive Properties of Plastic Lumber and ShapesD6109 Test Methods for Fl
23、exural Properties of Unreinforced and Reinforced Plastic Lumber and Related ProductsD6112 Test Methods for Compressive and Flexural Creep and Creep-Rupture of Plastic Lumber and ShapesD6341 Test Method for Determination of the Linear Coefficient of Thermal Expansion of Plastic Lumber and Plastic Lum
24、berShapes Between 30 and 140F (34.4 and 60C)D6662 Specification for Polyolefin-Based Plastic Lumber Decking BoardsD7032 Specification for Establishing Performance Ratings for Wood-Plastic Composite and Plastic Lumber Deck Boards, StairTreads, Guards, and HandrailsE84 Test Method for Surface Burning
25、Characteristics of Building Materials2.3 Other Documents:ASCE 7 Minimum Design Loads for Buildings and Other Structures33. Terminology3.1 Definitions of TermsFor definitions of terms used in this specification associated with plastics issues refer to theterminology contained in Terminology D883.3.2
26、Definitions:3.2.1 plastic lumber, na manufactured product made primarily from plastic materials (filled or unfilled), typically used as abuilding material for purposes similar to those of traditional lumber, which is usually rectangular in cross-section. (TerminologyD883)3.2.1.1 DiscussionPlastic lu
27、mber is typically supplied in sizes similar to those of traditional lumber board, timber and dimension lumber; howeverthe tolerances for plastic lumber and for traditional lumber are not necessarily the same. (Terminology D883)3.2.2 resin, na solid or pseudo solid organic material often of high mole
28、cular weight, which exhibits a tendency to flow whensubjected to stress, usually has a softening or melting range, and usually fractures conchoidally (Terminology D883).3.2.2.1 DiscussionIn a broad sense, the term is used to designate any polymer that is a basic material for plastics.2 For reference
29、dASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from American Society of Civil Engineers (ASCE), 1801 Alexander
30、Bell Dr., Reston, VA 20191, http:/www.asce.org.D7568 1723.3 Definitions of Terms Specific to This Standard:3.3.1 bulge, nconvex distortion (away from the center of the 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 t
31、he product in which there is a deviation in a direction perpendicular to the edge from a straightline from end to end along the length.3.3.3 cup, nconcave distortion (towards the center of the cross-section) of the face of the product from a straight line drawnfrom edge to edge across the width.3.3.
32、4 edge, nthe side of a rectangular-shaped product corresponding to the thickness.3.3.5 face, nthe side of a product corresponding to the width.3.3.6 reinforcement, na material added to the thermoplastic resin to improve its mechanical properties.3.3.7 self-supporting specimen, na specimen that remai
33、ns in place by its own structural characteristics both before and duringa fire test.3.3.8 structural grade plastic lumber, na solid, rectangular reinforced thermoplastic composite lumber product manufacturedfor load-bearing applications such as joists, beams, or columns in outdoor structures.3.3.9 t
34、est set, na full complement of test specimens required for a specific assessment.3.3.9.1 DiscussionAs an example, a test set for flexural properties (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 wi
35、dth, nthe greater dimension of the cross-sectional profile of a rectangular-shaped product, or the dimension of thecross-sectional profile of a square product.4. Ordering Information4.1 The information contained in this specification is intended to be helpful to producers, distributors, regulatory a
36、gencies andusers including designers, architects, and engineers. The information will also promote understanding between purchasers andsellers. The purchaser shall state whether this specification is to be used, select the preferred options permitted herein, and includethe allowable design informati
37、on in the invitation to bid and purchase order from the following:4.1.1 Title, number and date of this specification,4.1.2 Minimum allowable bending stress and apparent bending 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,
38、4.1.7 Cut length,4.1.8 Cross-sectional dimensions,4.1.9 Packing requirements,4.1.10 Palletization, if required,4.1.11 Marking, if other than specified.5. Dimensions and Permissible Variations5.1 It is permissible to produce SGPLeither in sizes that are similar to the standard dimensions of the wood
39、industry, or to otherdimensions designated by manufacturers or buyers. This specification does not limit the dimensional range of production.5.2 Use of a licensed Professional Engineer is recommended for designing and selecting SGPLproducts in accordance with thisspecification.5.3 ThicknessUnless ot
40、herwise specified in 4.1.8, product thickness tolerance shall be:For members less than 2 in. in nominal thickness the tolerance on thickness shall be +316 / -116 .Nominal (in.) Actual (in.) Tolerance (in.)2 112 +316 / -1163 212 +316 / -1164 312 +316 / -3325 412 +316 / -3326 512 + 316 / -18For member
41、s greater than 6 in. in nominal thickness the tolerance on thickness shall be +316 /-18 inch.5.4 WidthUnless otherwise specified in 4.1.8, product width shall be:D7568 173For members less than 3 in. in nominal width the tolerance on width shall be +316 /116 inch.Nominal (in.) Actual (in.) Tolerance(
42、in.)3 212 +316 / -1164 312 +316 / -3326 512 +316 / -3328 714 +316 / -1810 914 + 316 / -1812 1114 +14 / -532For members greater than 12 in. in nominal width the tolerance on width shall be +14 / -532 inch.5.5 LengthUnless otherwise specified in 4.1.7, products up to 20 ft shall have tolerances of 612
43、 inch. Over 20 feet thetolerances shall be 6 12-in. per 20-ft of length or fraction thereof. Measurement of lengths shall be made at 23 6 2C (73.4 64F) and relative humidity of 50 6 5 %.5.6 Flatness ToleranceProducts shall be flat with a maximum cup or bulge in the face limited to the tolerances in
44、Table 1 andTable 2. Linear interpolation of the values is acceptable for dimensions 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 () 116 in. 332 in. 18 in. 316 in. 14 in.TABLE 2 Cup or Bulge Tolerances Relati
45、ve to Nominal Size (square)Size, in. #4 in. 6 in. 8 in. 10 in. 12 in.Tolerance () 332 in. 18 in. 316 in. 14 in. 14 in.5.7 SquarenessUnless a specially shaped member is specified, the cross-section of all structural-grade plastic lumber productsshall be perpendicular (that is, 90 degree angle from fa
46、ce to edge of a square or rectangular shape and suited for the intendedpurpose).5.8 CrookCrook shall conform to the tolerances in Table 3. Linear interpolation of the values is acceptable for dimensionsother than listed.6. Performance Requirements6.1 Load Combinations: Plastic members subject to mul
47、tiple load types shall be checked for all applicable load combinations.Load factors and load reductions shall be determined in accordance with the applicable code or ASCE 7. All applicable loadcombinations shall be evaluated to determine the critical load combination to be used in design.NOTE 3Appli
48、cation of load duration factors to load combinations in which each load has a different associated duration is a complex process andvaries depending on whether the design engineer is using allowable stress design (ASD) or load and resistance factor design (LRFD) methodology. Aconservative design app
49、roach applies the load duration factor equal to the longest duration in the applicable load combination. More refined approachesfor specific applications can be found in the technical literature.6.2 Design Properties:6.2.1 All members shall be designed such that for all load combinations:fa#Fn3CD (1)where:fa = total applied stress in each combination (psi)Fn = allowable stress as calculated in 6.6.3.2, 6.7.2, 6.8.2.1, 6.8.3.1, or 6.9.3.2 (psi)CD = Load Duration Factor for the material an
