ASTM_A_1081_-_A_1081M_-_15.pdf

Designation:A1081/A1081M15Standard Test Method forEvaluating Bond of Seven-Wire Steel Prestressing Strand1This standard is issued under the fixed designation A1081/A1081M;the number immediately following the designation indicates theyear of original adoption 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.Scope*1.1 This test method describes procedures for determiningthe bond of seven-wire steel prestressing strand.The bonddetermined by this test method is stated as the tensile forcerequired to pull the strand through the cured mortar in acylindrical steel casing.The result of the test is the tensile forcemeasured on the loaded-end of the strand corresponding to amovement of 0.1 in.2.5 mm at the free-end of the strand.1.2 This test method is applicable either in inch-pound units(as Specification A1081)or SI units(as SpecificationA1081M).1.3 The values stated in either inch-pound units or in SIunits are to be regarded separately as standard.Within the text,SI units are shown in brackets.The values stated in eachsystem may not be exact equivalents;therefore,each systemshall be used independently of the other.Combining valuesfrom the two systems may result in non-conformance with thespecification.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 and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2A416/A416M Specification for Low-Relaxation,Seven-Wire Steel Strand for Prestressed ConcreteC33/C33M Specification for Concrete AggregatesC109/C109M Test Method for Compressive Strength ofHydraulic Cement Mortars(Using 2-in.or 50-mm CubeSpecimens)C150/C150M Specification for Portland CementC192/C192M Practice for Making and Curing Concrete TestSpecimens in the LaboratoryC670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsC1437 Test Method for Flow of Hydraulic Cement Mortar3.Terminology3.1 Definitions:3.1.1 bondthe adhesion of strand to concrete or mortar.3.1.2 bond breakera product wrapped around strand toprevent strand-to-concrete bond over the installed length.Extruded polystyrene foam pipe insulation is commonly usedfor this purpose.3.1.3 manufactured lengtha length of strand that is manu-factured in one continuous length.3.1.4 mortara mixture of cement,fine aggregate(that is,sand)and water.3.1.5 strandall references to strand in this test methodshall be interpreted to be Specification A416/A416M seven-wire prestressing steel strand with nominal diameters of 0.500in.12.70 mm or 0.600 in.15.24 mm.3.1.6 test specimenan assembly consisting of one steelcasing,one sample of strand and mortar.4.Summary of Test Method4.1 Six samples of seven-wire steel prestressing strand withnominal diameters of 0.500 in.12.7 mm or 0.600 in.15.24mm are selected from a single continuous length.Each of thesix strand samples are individually cast in a steel cylindercasing with a specified cement mortar.The strand is exposed onboth ends of the cylinder with a designated loaded-end andfree-end.Once the mortar reaches a specified compressivestrength,the cylinder with the embedded steel strand is loadedinto a tensile testing machine.The designated loaded-end ofthe steel strand is gripped by the tensile testing machine andpulled away from the cylinder at a specified displacement rate.The tensile force on the loaded-end of the strand is measuredalong with the corresponding displacement of the free-end.Theresult of the test is the tensile force measured at the loaded-endof the strand corresponding to a movement of 0.1 in.2.5 mmat the free-end of the strand.The results of each sample test inthe set of six are reported individually and as an average.1This test method is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.05 on Steel Reinforcement.Current edition approved Nov.1,2015.Published January 2016.Originallyapproved in 2013.Last previous edition approved as A1081/A1081M 13.DOI:10.1520/A1081_A1081M-15.2For 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.*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 States1 5.Significance and Use5.1 Prestressing steel strand is used in pre-tensioned andpost-tensioned concrete construction.5.2 In pre-tensioned concrete applications,the prestressingsteel strand is expected to transfer prestressing forces to