1、Designation:D756817Standard 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,the yea
2、r 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*1.1 This specification covers a type of plastic lumberproduct,defined as polyethylene-based structural-grade plasticlumbe
3、r(SGPL),for use as main framing members,includingjoists,stringers,beams,columns;and secondary framingmembers,including planking,posts and bracing;in outdoorstructures such as decks,boardwalks,docks,and platforms.1.2 This specification is applicable to solid,rectangularSGPL products where polyethylen
4、e 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 this specification shall not beused a
5、s 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 Due to thermodynamic effects that r
6、esult 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 addressed inthe material property assess
7、ments 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 document.1.7 For purposes of this standard,an SGPL
8、 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 combinations of both virgin andrecycled polyethylene materia
9、l 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 additives are typicallyadded to SGPL formulations.Exa
10、mples 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 of SGPL products.Fillers thatcause the product to fail t
11、he 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 additionally the propertiesspecified in Section 6 of this specific
12、ation.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,such products are not covered in this document.1.14 Products that
13、 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).NOTE1Calculation of time-dependent properties in Annex A1 isbased on the assumption that the produc
14、t 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 and has therefore beendeveloped in the format of a procurement specif
15、ication.1.16 Criteria for design are included as part of this specifi-cation for SGPL products.1This specification is under the jurisdiction of ASTM Committee D20 onPlastics and is the direct responsibility of Subcommittee D20.20 on Plastic Lumber.Current edition approved March 1,2017.Published Marc
16、h 2017.Originallyapproved in 2012.Last previous edition approved in 2013 as D7568 13.DOI:10.1520/D756817.*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 on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom