ASTM_C_1231_-_C_1231M_-_15.pdf

Designation:C1231/C1231M15Standard Practice forUse of Unbonded Caps in Determination of CompressiveStrength of Hardened Cylindrical Concrete Specimens1This standard is issued under the fixed designation C1231/C1231M;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 practice covers requirements for a capping systemusing unbonded caps for testing concrete cylinders molded inaccordance with Practice C31/C31M or C192/C192M,or coresobtained in accordance with Test Method C42/C42M.Un-bonded neoprene caps of a defined hardness are permitted tobe used for testing for a specified maximum number of reuseswithout qualification testing up to a certain concrete compres-sive strength level.Above that strength,level neoprene capswill require qualification testing.Qualification testing is re-quired for all elastomeric materials other than neopreneregardless of the concrete strength.1.2 Unbonded caps are not to be used for acceptance testingof concrete with compressive strength below 10 MPa 1500 psi or above 80 MPa 12 000 psi.1.3 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-conformancewith the standard.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.(WarningConcrete specimens tested with unbonded caps rupture moreviolently than comparable specimens tested with bonded caps.The safety precautions given in the Manual of Aggregate andConcrete Testing are recommended.2)2.Referenced Documents2.1 ASTM Standards:3C31/C31M Practice for Making and Curing Concrete TestSpecimens in the FieldC39/C39M Test Method for Compressive Strength of Cylin-drical Concrete SpecimensC42/C42M Test Method for Obtaining and Testing DrilledCores and Sawed Beams of ConcreteC192/C192M Practice for Making and Curing Concrete TestSpecimens in the LaboratoryC617 Practice for Capping Cylindrical Concrete SpecimensD2000 Classification System for Rubber Products in Auto-motive Applications3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 pad,nan unbonded elastomeric pad.3.1.2 unbonded cap,na metal retainer and an elastomericpad.4.Significance and Use4.1 This practice provides for using an unbonded cappingsystem in testing hardened concrete cylinders made in accor-dance with Practices C31/C31M or C192/C192M,or coresobtained in accordance with Test Method C42/C42M in lieu ofthe capping systems described in Practice C617.4.2 The elastomeric pads deform in initial loading to con-form to the contour of the ends of the test specimens and arerestrained from excessive lateral spreading by plates and metalrings to provide a uniform distribution of load from the bearingblocks of the testing machine to the ends of the concrete ormortar specimens.1This practice is under the jurisdiction of ASTM Committee C09 on Concreteand ConcreteAggregates and is the direct responsibility of Subcommittee C09.61 onTesting for Strength.Current edition approved Dec.1,2015.Published February 2016.Originallyapproved in 1993.Last previous edition approved in 2014 as C1231/C1231M 14.DOI:10.1520/C1231_C1231M-15.2Section on Safety Precautions,Manual of Aggregate and Concrete Testing,Annual Book of ASTM Standards,Vol 04.02.3For 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.Materials and Apparatus5.1 Materials and equipment necessary to produce ends ofthe reference specimens that conform to planeness require-ments of Test Method C39/C39M and the requirements ofPractice C617.This may include grinding equipment or cap-ping materials and equipment to produce neat cement paste,high strength gypsum plaster,or sulfur mortar caps.5.2 Elastomeric Pads:5.2.1 Pads shall be 13 6 2 mm 126116in.thick and thediameter shall not be more than 2 mm 116in.smaller than theinside diameter of the retaining ring.5.2.2 Pads shall be made from polychloroprene(neoprene)meeting the requirements of Classification D2000 as follows:Shore ADurometerClassification D2000Line Call-Out50M2BC51460M2BC61470M2BC714The tolerance on ShoreAdurometer hardn