1、Designation: D7508/D7508M 10 (Reapproved 2015) An American National StandardStandard Specification forPolyolefin Chopped Strands for Use in Concrete1This standard is issued under the fixed designation D7508/D7508M; the number immediately following the designation indicates theyear of original adopti
2、on or, in the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers polyolefin chopped strands(fibers) for use in co
3、ncrete.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conforman
4、cewith the standard.1.3 The following safety hazards caveat pertains only to thetest methods described in this specification: This standard doesnot purport to address all of the safety concerns, if any,associated with its use. It is the responsibility of the user of thisstandard to establish appropr
5、iate safety and health practicesand determine the applicability of regulatory limitations priorto use.2. Referenced Documents2.1 ASTM Standards:2C1116/C1116M Specification for Fiber-Reinforced ConcreteD123 Terminology Relating to TextilesD1577 Test Methods for Linear Density of Textile FibersD1776 P
6、ractice for Conditioning and Testing TextilesD1907 Test Method for Linear Density of Yarn (Yarn Num-ber) by the Skein MethodD2256 Test Method for Tensile Properties of Yarns by theSingle-Strand MethodD2257 Test Method for Extractable Matter in TextilesD2258 Practice for Sampling Yarn for TestingD321
7、8 Specification for Polyolefin Monofilaments3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this Specification,refer to Terminology D123.3.2 Definitions of Terms Specific to This Standard:3.2.1 chopped strand, ncut staple polymer fiber of speci-fied lengths.3.2.2 fiber, nas used
8、 for concrete reinforcement, choppedstrand that is mixed into concrete or mortar.3.2.2.1 DiscussionFiber used for concrete or mortar rein-forcement is available in various deniers. These include:(a) Macro polyolefin fiber which has linear density greaterthan or equal to 580 denier (equivalent diamet
9、er 0.3 mm).(b) Micro polyolefin fiber which has a linear density of lessthan 580 denier (equivalent diameter 0.3 mm).(c) Hybrid fiber which include a combination of macropolyolefin and micro polyolefin fibers.(d) Multi-length fibers which consist of chopped strands ofvarious lengths of fiber.(e) Gra
10、ded fiber which consists of a gradation of multiplelength and multiple denier fibers.3.2.3 fiber reinforced concrete (FRC), nhydraulic cementconcrete that includes chopped strands (fibers).3.2.4 finish content, nthe percent by mass of finish extrac-tions on the fiber.3.2.5 high-tenacity fiber, na ma
11、nufactured fiber that be-longs to a generic class of fibers having exceptional breakingstrength; or having a breaking strength significantly greaterthan the average strength of other (regular tenacity) fibers inthe same generic class of equivalent linear densities.3.2.6 polyolefin, nany long-chain s
12、ynthetic polymer com-posed of at least 85 % by weight of ethylene, propylene, orother olefin units (monomers), except amorphous (noncrystal-line) polyolefin.3.2.7 reprocessed materials, nmaterials that have beenrecycled from another process.3.2.8 strand, na single fiber, filament, or monofilament.3.
13、2.9 skein, na continuous strand of yarn, wound on ahand or motorized reel.3.2.10 yarn, nas used for fiber concrete reinforcement,narrow slit extruded film.1This specification is under the jurisdiction of ASTM Committee D13 onTextiles and is the direct responsibility of Subcommittee D13.58 on Yarns a
14、ndFibers.Current edition approved July 1, 2015. Published September 2015. Originallyapproved in 2010. Last previous edition approved in 2010 as D7508/D7508M10.DOI: 10.1520/D7508_D7508M-10R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serv
15、iceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1SPECIFICATIONS4. Chopped Strands for FRC4.1 Polyolefin c
16、hopped strands shall be manufactured andtested to specific targets and tolerances as detailed in themanufactures product specifications.4.2 Materials shall be tested during processing (skeins oruncut strands) and after processing (chopped strands).5. Summary5.1 Summaries of the various testing proce
17、dures are in-cluded in the referenced test methods, or in pertinent sectionsof this specification.5.1.1 Denier: D1577 Test Method for Linear Density ofTextile FibersD1907 Linear Density of Yarn by Skein Method5.1.2 Tensile: D2256 Test Method for Tensile Properties ofYarns by the Single-Strand Method
18、D3218 Specification for Polyolefin Monofilaments5.1.3 TenacityThe tensile stress expressed force per unitlinear density of the unstrained specimen. (Sometimes ex-pressed in grams per denier, or GPD.)D2256 Test Method for Tensile Properties of Yarns by theSingle-Strand Method5.1.4 Elongation: D2256 T
19、est Method for Tensile Proper-ties of Yarns by the Single-Strand MethodD3218 Specification for Polyolefin Monofilaments5.1.5 Initial Modulus: D2256 Test Method for TensileProperties of Yarns by the Single-Strand MethodD3218 Specification for Polyolefin Monofilaments5.1.6 Equivalent DiameterThe diame
20、ter of a circle havingthe same cross-sectional area as the fiber or strand. Themeasurement may be derived from stated calculation providedin Eq 1.5.1.7 Finish ContentBased on percent of total mass.Several methods of finish extractions are recognized includingthe use of a NMR system (Nuclear Magnetic
21、 Residence),Rapid Oil Extraction Apparatus, and spin finish analysis basedon Test Method D2257. None of these systems or this standardaddresses the chemical properties or types of chemicals thatmay be contained in the finish applied. Certain chemicals atvarious dosages may cause change in the proper
22、ties of concretemix performance such as air gain.5.1.8 Fiber LengthTotal distance from the outer ends ofthe finished fiber or developed length.6. Significance and Use6.1 Acceptance TestingThe test methods in SpecificationD2256 and D3218 for the determination of the properties ofpolyolefin cut strand
23、s are considered satisfactory for accep-tance testing of commercial shipments of polyolefin cut strandsfor use in concrete.6.2 Laboratory Correlation TestingIf there are differencesof practical significance between reported test results for twolaboratories (or more) a comparative test should be perf
24、ormedto determine if there is a statistical bias between them, usingcompetent statistical assistance. As a minimum, use testsamples that are as homogeneous as possible, drawn from thematerial from which the disparate test results were obtained,and randomly assigned in equal numbers to each laborator
25、y fortesting. The test results from the two laboratories should becompared using a statistical test for unpaired data, at aprobability level chosen prior to the testing series. If a bias isfound either its cause must be found and corrected or future testresults for that material must be adjusted in
26、consideration of theknown bias.7. Sampling and Number of Specimens7.1 Take samples as directed in the applicable materialspecification, or as agreed upon by the purchaser and thesupplier. In the absence of an applicable material specification,or other agreement, take a lot sample and laboratory samp
27、les asdirected in Practices D2258 or D3218.NOTE 1An adequate specification or other agreement between thepurchaser and the supplier requires taking into account variability betweenshipping units, between packages, or ends within a shipping unit, andbetween specimens from a single package so as to pr
28、ovide a sampling planwith a meaningful producers risk, consumers risk, acceptable qualitylevel, and limiting quality level.8. Fiber Length and Permissible Variations8.1 A representative fiber sample of an order quantity shallbe 30 fibers obtained from three grab samples by combining 10randomly selec
29、ted fibers from each grab sample. If deemednecessary, the producer shall choose to select the 10 specimensat different set intervals in order to obtain a more accuraterepresentation of the production lot. Fiber length or lengths, fora given order quantity, shall be determined as the averagelength of
30、 the 30 fibers to the nearest mm.8.2 Average fiber length, shall be within +10 % and 10 %of the specified length.8.3 Fiber products that are defined by a range of lengths orgraded lengths, shall have 95 % of measured lengths fall withinthe specified range.8.4 Report:8.4.1 Fiber length to nearest mm.
31、8.4.2 For hybrids and multi-length fibers, range of equiva-lent diameters, linear densities, and fiber lengths as appropri-ate.9. Linear Density, Cross Sectional Area, EquivalentDiameter of FRC Strand and Finish Content9.1 Linear Density of FRC Chopped Strand:9.1.1 ApparatusBalance, calipers, skein
32、reel, or templatesmay be used. All measuring equipment, including templates,must be calibrated and inspected at regular intervals.9.1.2 Procedure by Denier or Tex MethodDetermine thedirect yarn number in tex to three significant figures or denierto one significant figure as directed in 5.1.1.9.2 Equ
33、ivalent Diameter of FRC Chopped Strand, d:9.2.1 If strands have a cross section that is circular, measurethe diameter with a set of calipers that measure to at least twosignificant figures in mm. The measured diameter is theequivalent diameter, d.9.2.2 If the strands have a cross section that is rec
34、tangular,measure the width, w, and thickness, t, with a set of calipersD7508/D7508M 10 (2015)2that measure to at least two significant figures in mm. Calculatethe equivalent diameter using the following equation:d 5 4wt(1)where:d = equivalent diameter, mm,t = measured thickness of strand, mm, andw =
35、 measured width of strand, mm.9.2.3 If the strands have an irregular cross section, calculatethe equivalent diameter from the linear density (tex or denier)using the following equation:d 5!4Stex1000Dor d 5!4Sdenier9000D(2)where:d = equivalent diameter, mm, and = unit density in grams per cubic centi
36、meter (specificgravity) of the polyolefin material.9.3 Report:9.3.1 That the specimens were tested in accordance withSpecification D7508/D7508M, and describe the material orproduct sampled and the method of sampling used,9.3.2 Equivalent diameter in two significant figures in mmfor macro polyolefin
37、fiber, and three significant figures in mmfor micro polyolefin fiber,9.3.3 Linear density (tex or denier) to the nearest wholenumber, and9.3.4 Fiber length to nearest mm.9.4 Finish Content:9.4.1 There are multiple methods and systems used toanalyze the level of finish applied. Any system used in thi
38、sanalysis shall have multiple laboratory correlation studies orMSA (Measurement System Analysis) from at least twoseparate labs to ensure the accuracy and repeatability ofmeasurement system. See 6.2.9.4.2 ReportThe percent by mass of finish content andsystem/process used to perform the analysis.10.
39、Tensile and Tenacity Properties10.1 ApparatusTensile testing machine of a type as speci-fied in Test Methods D2256 and D3218. All types of tensilemachines described in Test Methods D2256 and D3218 areadequate to test polyolefin strand materials. Ensure that theload cell(s) chosen are relative to the
40、 size and strength of thestrand being tested. The load cell capacity should be in rangeand comparable of the expected ultimate tensile strength. Typeof grips or jaws used to hold specimens must be adequate toproperly secure strand ends and to prevent strands from slips orfalse breaks.10.2 ProcedureD
41、etermine the breaking force, the break-ing tenacity, and the elongation of adequately conditionedpolyolefin filaments, using Practice D1776. The initial modulusshall also be calculated during the testing if required by thepurchaser. Tensile, tenacity and modulus of deformed fibersmay be tested prior
42、 to the deforming process, but not required.10.3 Calculate:10.3.1 TenacityUsing linear density as the breaking loaddetermined in 10.2 divided by the linear density determined in9.1, grams/denier, or10.3.2 TenacityUsing tex as the breaking load determinedin 10.2 divided by 9 times the tex determined
43、in 9.1, and10.3.3 Relative Tensile StrengthFrom the breaking loaddetermined in 10.2 and the equivalent diameter determined in9.2, using the following equation:Tr54Lbd2(3)where:Tr= relative tensile strength, MPa,Lb= breaking load. N, andd = equivalent diameter of fiber, mm.10.3.4 Using DenierPeak loa
44、d in grams/denier = breakingtenacity (grams per denier or GPD).10.3.5 Using TexPeak load in grams/(tex)(9) = breakingtenacity (grams per denier or GPD).10.4 Relative Tensile Strength:10.4.1 Relative Tensile Strength shall also be reported. Thisshall be calculated from both the cross sectional area a
45、nd thebreaking force.NOTE 2The relative tensile strength of macro polyolefin fibers is acommon requirement due to the significant correlation of fiber strength toconcrete performance.10.5 Report:10.5.1 That the specimens were tested as directed in Section10 of this Specification D7508. Describe the
46、material orproduct sampled and the method of sampling used.10.5.2 The following information for each laboratory sam-pling unit and for the lot:10.5.2.1 Breaking tenacity stated in grams per denier, or10.5.2.2 Relative tensile strength, MPa.10.5.2.3 Elongation at break, as a percentage of the nominal
47、gage length, and10.5.2.4 At the option of the specifier of tests, the initialmodulus, MPa.10.5.3 Hybrids (macro) must state all fiber types tensileproperties.11. Conformance11.1 The purchaser and the supplier shall agree on aprocedure to establish conformance, including control chartsfurnished by th
48、e supplier, a sequential-sampling plan, or thedouble-sampling plan outlined in 11.2.11.2 In the absence of a control-chart or sequential-sampling plan, proceed as directed in 11.2.1 11.2.3.11.2.1 If the test results for the lot conform to the tolerancesfor all characteristics agreed upon, consider t
49、he lot a validdelivery.11.2.2 If the test results for one or more characteristics donot conform to the tolerances, take a new laboratory samplefrom either the original lot sample or a new lot sample. Retestthe lot for the characteristic(s) that did not conform to thetolerances in the first test, and average the results of the firstD7508/D7508M 10 (2015)3and second samples as if all results were from one test ofdouble the original number of specimens. If the new average(s)conform(s) to the specified tolerances, consider the lot a validde
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