ASTM_C_801_-_98.pdf

Designation:C 801 98Standard Test Method forDetermining the Mechanical Properties ofHardened Concrete Under Triaxial Loads1This standard is issued under the fixed designation C 801;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the procedures for testinghardened concrete when subjected to triaxial stress conditions.Materials other than concrete,cement paste,or mortar areexcluded.When the determination of the strength of concreteunder a triaxial state of stress is made according to this testmethod,two of the three principal stresses are always equal.There is no provision made for the measurement of porepressures;therefore all strength values are in terms of totalstress.1.2 The values stated in inch-pound units are to be regardedas the standard.The values given in parentheses are mathemati-cal conversions to SI units which are provided for informationonly and are not considered standard.1.3 This standard does not purport to address all of thesafety problems,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:C 39 Test Method for Compressive Strength of CylindricalConcrete Specimens2C 192 Practice for Making and Curing Concrete Test Speci-mens in the Laboratory2C 512 Test Method for Creep of Concrete in Compression2C 617 Practice for Capping Cylindrical Concrete Speci-mens2E 4 Practices for Load Verification of Testing Machines23.Significance and Use3.1 This test method provides data useful in determining thestrength and deformation characteristics of concrete such asshear strength at various lateral pressures,angle of shearingresistance,strength in pure shear,deformation modulus,andcreep behavior.4.Apparatus4.1 Loading DeviceA suitable device for applying andmeasuring axial load to the specimen.It must be of sufficientcapacity to apply the required loads at specified rates.It shouldbe verified at suitable time intervals in accordance with theprocedures given in Practices E 4,and should comply with therequirements prescribed therein.4.2 Triaxial Compression ChamberA device in which thetest specimen may be enclosed in an impermeable,flexiblemembrane,placed between two hardened bearing blocks,andsubjected to hydraulic pressure and deviator stress.The bearingblocks must be of steel,the bearing faces of which should behardened to a minimum of 55 HRC,and which should notdepart from plane surfaces by more than 0.0005 in.(0.0127mm)when the blocks are new and should be maintained withina permissible variation of 0.001 in.(0.0254 mm).In order todevelop the required hydraulic pressure,the apparatus shouldconsist of a high pressure cylinder with an overflow valve,abase,suitable entry ports for filling the cylinder with hydraulicfluid and applying the lateral pressure,and hoses,gages andvalves as needed(1,2,3,4).3Fig.1 and Fig.2 illustrate triaxialchambers which have proved to be satisfactory.4.3 Combination DevicesAlternatively,devices may beused which combine the function of loading device andpressure chamber.Fig.3 illustrates one such device(5,6,7,8).4.4 Pressure-Maintaining DeviceAhydraulic pump,pres-sure intensifier,or other system of sufficient capacity tomaintain the desired pressures in the triaxial compressionchamber.4.5 Strain-Measuring DevicesSuitable devices must beprovided for the measurement of strain in the specimen.Suchdevices should be readable to the nearest 0.0001 in.(0.00254mm)and accurate to within 0.0001 in.(0.00254 mm)in any0.001-in.(0.0254-mm)range,and within 0.0002 in.(0.00508mm)in any 0.0100-in.(0.254-mm)range.Such devices mayconsist of micrometer screws,dial micrometers or linearvariable differential transformers securely attached to the highpressure cylinder,and designed to measure bearing block travel(5,6,7,9).4.5.1 Vibrating wire or electrical resistance strain gages maybe embedded in the concrete,aligned along the axis of the1This test method is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC09.61on Testing for Strength.Current edition approved Nov.10,1998.Published March 1999.Originallypublished as C 801 75.Last previous edition C 801 91.2Annual Book of ASTM Standards,Vol 04.02.3The boldface numbers in parentheses refer to the list of references at the end ofthis test method.1Copyright ASTM,100 Barr Harbor Drive,West Conshohocken,PA 19428-2959,United States.specimen for measuring axial deformation,or they may beaffixed to the surface of the specimen,in which case theyshould be placed at two diametrically opposite locations and atmidlength