ASTM_C_1550_-_12a.pdf

Designation:C155012aStandard Test Method forFlexural Toughness of Fiber Reinforced Concrete(UsingCentrally Loaded Round Panel)1This standard is issued under the fixed designation C1550;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.Scope*1.1 This test method covers the determination of flexuraltoughness of fiber-reinforced concrete expressed as energyabsorption in the post-crack range using a round panel sup-ported on three symmetrically arranged pivots and subjected toa central point load.The performance of specimens tested bythis method is quantified in terms of the energy absorbedbetween the onset of loading and selected values of centraldeflection.1.2 This test method provides for the scaling of resultswhenever specimens do not comply with the target thicknessand diameter,as long as dimensions do not fall outside of givenlimits.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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:2C31/C31M Practice for Making and Curing Concrete TestSpecimens in the FieldC125 Terminology Relating to Concrete and Concrete Ag-gregatesC670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction Materials3.Terminology3.1 DefinitionsFor definitions of terms used in this testmethod,refer to Terminology C125.3.2 Definitions of Terms Specific to This Standard:3.2.1 central deflectionthe net deflection at the center ofthe panel measured relative to a plane defined by the threepivots used to support the panel;this is a conditioned deflectionthat excludes extraneous deformations of the load train andlocal crushing of the panel at the point of load application andpoints of support.3.2.2 compliancea measure of the tendency of a structureto deflect under load,found as the inverse of stiffness ordeflection divided by the corresponding load.3.2.3 load trainthose parts of a testing machine thatexperience load and undergo straining during a mechanicaltest,including the actuator,frame,support fixtures,load cell,and specimen.3.2.4 toughnessthe energy absorbed by the specimenequivalent to the area under the load-deflection curve betweenthe onset of loading and a specified central deflection.4.Summary of Test Method4.1 Molded round panels of cast fiber-reinforced concrete orfiber-reinforced shotcrete are subjected to a central point loadwhile supported on three symmetrically arranged pivots.Theload is applied through a hemispherical-ended steel pistonadvanced at a prescribed rate of displacement.Load anddeflection are recorded simultaneously up to a specified centraldeflection.The energy absorbed by the panel up to a specifiedcentral deflection is representative of the flexural toughness ofthe fiber-reinforced concrete panel.5.Significance and Use5.1 The post-crack behavior of plate-like,fiber-reinforcedconcrete structural members is well represented by a centrallyloaded round panel test specimen that is simply supported onthree pivots symmetrically arranged around its circumference.Such a test panel experiences bi-axial bending in response to acentral point load and exhibits a mode of failure related to thein situ behavior of structures.The post-crack performance ofround panels subject to a central point load can be represented1This test method is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC09.42 on Fiber-Reinforced Concrete.Current edition approved Dec.1,2012.Published December 2012.Originallyapproved in 2002.Last previous edition approved in 2012 as C1550 12.DOI:10.1520/C1550-12A.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 by the energy absorbed by the panel up to a specified centraldeflection.In this test method,the energy absorbed up to aspecified central deflection is taken to represent the ability of afiber-reinforced concrete to redistribute stress following crack-ing.NOTE1The use of three pivoted point supports in the test configura-tion results in determinate out-of-plane reactions prior to cracking,however the support reactions are