ASTM_A_944_-_10_2015.pdf

Designation:A94410(Reapproved 2015)Standard Test Method forComparing Bond Strength of Steel Reinforcing Bars toConcrete Using Beam-End Specimens1This standard is issued under the fixed designation A944;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,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.Scope1.1 This test method describes procedures to establish therelative bond strength of steel reinforcing bars in concrete.1.2 This test method is intended to determine the effects ofsurface preparation or condition(such as bar coatings)on thebond strength of deformed steel reinforcing bars(of sizesranging from No.10 to No.36 No.3 to No.11)to concrete.1.3 The bond strengths obtained using this test method arenot directly applicable to the design of reinforced concretemembers.NOTE1The bond strengths obtained using this test method aregenerally higher than obtained in development or splice tests using beamswith the same embedment lengths.The results obtained using this testmethod should only be used for comparisons with results for otherreinforcing bars tested using this method.1.4 The values stated in inch-pound units are to be regardedas standard.The values given in brackets are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.5 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:2A775/A775M Specification for Epoxy-Coated Steel Rein-forcing BarsC192/C192M Practice for Making and Curing Concrete TestSpecimens in the LaboratoryE4 Practices for Force Verification of Testing MachinesE575 Practice for Reporting Data from Structural Tests ofBuilding Constructions,Elements,Connections,and As-semblies3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 bond strength,nmaximum measured load in a ten-sile bond test of a steel reinforcing bar.3.1.2 bonded length,nthe length of the test bar that is incontact with concrete.3.1.3 concrete cover,nminimum distance between thesurface of the test bar and the top or bottom of the testspecimen.3.1.4 embedment length,nthe distance from the surface ofthe concrete test specimen to the installed end of the steelreinforcing bar.This equals the sum of the lead length and thebonded length.3.1.5 lead length,nthe length of the test bar that is not incontact with concrete but is between the surface of the concretetest specimen and the bonded length.3.1.6 relative rib area,nratio of the projected rib areanormal to bar axis to the product of the nominal bar perimeterand the center-to-center rib spacing.3.2 Symbols:Cb=Concrete cover,mm in.db=Nominal diameter of reinforcing bar,mm in.le=Embedment length,mm in.4.Apparatus4.1 EquipmentA schematic of a suitable testing system isshown in Fig.1.The loading system shall be capable ofmeasuring the forces to an accuracy within 62%of theapplied load,when calibrated in accordance with Practices E4.The test system shall have sufficient capacity to preventyielding of its various components and shall ensure that theapplied tensile load remains parallel to the axis of the steelreinforcing bar during testing.4.2 Compression Reaction PlateThe compression reac-tion plate shall be placed a minimum clear distance equal to 0.9lemeasured from the center of the test bar to the edge of thereaction plate.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 November 2015.Originallyapproved in 1995.Last previous edition approved in 2010 as A944 10.DOI:10.1520/A0944-10R15.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.3 Bar Displacement MeasurementsDisplacements of theloaded and free ends of the steel reinforcing bar shall bemeasured with respect to the loaded and free surfaces,respectively,of the concrete using suitable measurement de-vices.Dial gages having the smallest division of not more than25 m 0.001 in.or linear variable differential transformers(LVDTs)with equal or superior accuracy are examples ofsatisfactory devices.5.Test Specimen5.1 Beam-End SpecimenThe test specimen shall consist ofthe test bar cast in a block of reinforced concrete 600 6 25 mm24 6 1 in.long