1、Designation:C169809(Reapproved 2014)Standard Test Method forAutogenous Strain of Cement Paste and Mortar1This standard is issued under the fixed designation C1698;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revis
2、ion.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 measures the bulk strain of a sealedcement paste or mortar specimen,including those containingadmixtures,various sup
3、plementary cementitious materials(SCM),and other fine materials,at constant temperature andnot subjected to external forces,from the time of final settinguntil a specified age.This strain is known as autogenous strain.Autogenous strain is most significant in concrete with lowwater-cementitious mater
4、ials ratio(w/cm)(See Note 1).NOTE1A low water-cementitious materials ratio(w/cm)can beconsidered to be a water to cement ratio of 0.40 or lower for this test.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This standard d
5、oes 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.(WarningFreshhydraulic cementitious m
6、ixtures are caustic and may causechemical burns to skin and tissue upon prolonged exposure.2)2.Referenced Documents2.1 ASTM Standards:3C125 Terminology Relating to Concrete and Concrete Ag-gregatesC157/C157M Test Method for Length Change of HardenedHydraulic-Cement Mortar and ConcreteC191 Test Metho
7、ds for Time of Setting of Hydraulic Cementby Vicat NeedleC192/C192M Practice for Making and Curing Concrete TestSpecimens in the LaboratoryC219 Terminology Relating to Hydraulic CementC305 Practice for Mechanical Mixing of Hydraulic CementPastes and Mortars of Plastic ConsistencyC403/C403M Test Meth
8、od for Time of Setting of ConcreteMixtures by Penetration ResistanceC1005 Specification for Reference Masses and Devices forDetermining Mass and Volume for Use in the PhysicalTesting of Hydraulic Cements2.2 API Specification4RP 10B-2/ISO 10426-2 Recommended Practice for TestingWell Cements3.Terminol
9、ogy3.1 Definitions:3.1.1 For definitions of terms used in this test method,referto Terminologies C125 and C219.3.2 Definitions of Terms Specific to This Standard:3.2.1 autogenous strain,nthe bulk strain of a sealedspecimen of a cementitious mixture,not subjected to externalforces and under constant
10、temperature,measured from the timeof final setting until a specified age;negative strain correspondsto shrinkage and positive strain corresponds to expansion.4.Summary of Test Method4.1 Aspecimen of freshly mixed paste or mortar is preparedusing a corrugated mold that offers little resistance to len
11、gthchange of the specimen.The mold is sealed to prevent moistureloss and the specimen is stored at constant temperature.Starting at the time of final setting,the length of the specimenis measured using a dilatometer.The change in length isrecorded at regular time intervals until the designated age.T
12、hechange in length and original length of the specimen are usedto compute the autogenous strain.5.Significance and Use5.1 Autogenous strain is the self-created bulk strain ofcement paste,mortar,or concrete during hardening at constanttemperature.In conventional concrete,autogenous shrinkagestrain is
13、 generally negligible,but in concrete with low water-cementitious materials ratio(w/cm)or with silica fume it may1This test method is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC09.68 on Volume Change.Current editio
14、n approved Oct.1,2014.Published November 2014.Originallyapproved in 2009.Last previous edition approved in 2009 as C1698-09.DOI:10.1520/C1698-09R14.2Section on Safety Precautions,Manual of Aggregate and Concrete Testing,Annual Book of ASTM Standards,Vol.04.02.3For referenced ASTM standards,visit the
15、 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.4Available from American Petroleum Institute(API),1220 L.St.,NW,Washington,DC 20005-4070,http:/www.api.org
16、.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 be considerable(1).5Restraint of the autogenous strain byaggregates or adjoining structural members may result information of micro and macro cracks that impair strength,durability and aesthetics.Cracks may also be a problem withregard to hygienic cleaning of surfaces.5.2 An accurate measurement of the autogenous strain ofcementitious mixtures with low w/cm is important for evalu-ating
