1、Designation: C1581/C1581M 18aStandard Test Method forDetermining Age at Cracking and Induced Tensile StressCharacteristics of Mortar and Concrete under RestrainedShrinkage1This standard is issued under the fixed designation C1581/C1581M; the number immediately following the designation indicates the
2、year 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 test method covers the laboratory determinati
3、on ofthe age at cracking and induced tensile stress characteristics ofmortar or concrete specimens under restrained shrinkage. Theprocedure can be used to determine the effects of variations inthe proportions and material properties of mortar or concreteon cracking due to both drying shrinkage and d
4、eformationscaused by autogenous shrinkage and heat of hydration.1.2 This test method is not intended for expansive materials.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,
5、 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
6、establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior touse.(WarningFresh hydraulic cementitious mixtures arecaustic and may cause chemical burns to skin and tissue uponprolonged exposure.2)1.5 This international standard
7、was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Refere
8、nced Documents2.1 ASTM Standards:3C33/C33M Specification for Concrete AggregatesC125 Terminology Relating to Concrete and Concrete Ag-gregatesC138/C138M Test Method for Density (Unit Weight), Yield,and Air Content (Gravimetric) of ConcreteC143/C143M Test Method for Slump of Hydraulic-CementConcreteC
9、150/C150M Specification for Portland CementC171 Specification for Sheet Materials for Curing ConcreteC192/C192M Practice for Making and Curing Concrete TestSpecimens in the LaboratoryC387/C387M Specification for Packaged, Dry, CombinedMaterials for Concrete and High Strength MortarC595/C595M Specifi
10、cation for Blended Hydraulic CementsC1157/C1157M Performance Specification for HydraulicCementC1437 Test Method for Flow of Hydraulic Cement MortarF441/F441M Specification for Chlorinated Poly(Vinyl Chlo-ride) (CPVC) Plastic Pipe, Schedules 40 and 802.2 ASME Standards:4B 46.1 Surface Texture (Surfac
11、e Roughness, Waviness andLay)3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method, referto Terminology C125.3.2 Definitions of Terms Specific to This Standard:1This test method is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is
12、the direct responsibility of SubcommitteeC09.68 on Volume Change.Current edition approved July 1, 2018. Published September 2018. Originallyapproved in 2004. Last previous edition approved in 2018 as C1581/C1581M 18.DOI: 10.1520/C1581_C1581M-18A.2Section on Safety Precautions, Manual of Aggregate an
13、d 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.
14、4Available from American Society of Mechanical Engineers (ASME), ASMEInternational Headquarters, Three Park Ave., New York, NY 10016-5990, http:/www.asme.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Consho
15、hocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Orga
16、nization Technical Barriers to Trade (TBT) Committee.13.2.1 age at cracking, nthe age of each test specimen,measured from the time of casting, when a sudden decrease instrain occurs.3.2.2 elapsed time, nthe difference between each recordedtime when strain is measured and the time when drying wasinit
17、iated.3.2.3 initial strain, nthe strain value in the steel ring whendrying is initiated.3.2.4 net strain, nthe value corresponding to the differ-ence between the strain in the steel ring at each recorded timeand the initial strain.3.2.5 strain rate factor, nthe slope of the best-fit line to thevalue
18、s of net strain plotted as a function of the square root ofelapsed time for each strain gage.3.2.6 stress rate, nthe rate of tensile stress development inthe test specimen at the time of cracking or when the test isterminated and obtained in accordance with Eq 2.4. Summary of Test Method4.1 A sample
19、 of freshly mixed mortar or concrete is com-pacted in a circular mold around an instrumented steel ring.The compressive strain developed in the steel ring caused byshrinkage of the mortar or concrete specimen is measured fromthe time of casting (1-6).5Cracking of the test specimen isindicated by a s
20、udden decrease in the steel ring strain. The ageat cracking and the rate of tensile stress development in the testspecimen are indicators of the materials resistance to crackingunder restrained shrinkage.5. Significance and Use5.1 This test method is for relative comparison of materialsand is not in
21、tended to determine the age at cracking of mortaror concrete in any specific type of structure, configuration, orexposure.5.2 This test method is applicable to mixtures with aggre-gates of 13-mm 0.5-in. maximum nominal size or less.5.3 This test method is useful for determining the relativelikelihoo
22、d of early-age cracking of different cementitiousmixtures and for aiding in the selection of cement-basedmaterials that are less likely to crack under retrained shrinkage.Actual cracking tendency in service depends on many variablesincluding type of structure, degree of restraint, rate of propertyde
23、velopment, construction and curing methods, and environ-mental conditions.5.4 This test method can be used to determine the relativeeffects of material variations on induced tensile stresses andcracking potential. These variations can include, but are notlimited to, aggregate source, aggregate grada
24、tion, cement type,cement content, water content, supplementary cementingmaterials, or chemical admixtures.5.5 For materials that have not cracked during the test, therate of tensile stress development at the time the test isterminated provides a basis for comparison of the materials.6. Apparatus6.1
25、Steel RingStructural steel pipe with a wall thickness of13 6 1 mm 0.50 6 0.05 in., an outside diameter of 330 63 mm 13.0 6 0.12 in. and a height of 150 6 6 mm 6.0 60.25 in. (see Fig. 1). Machine the inner and outer faces toproduce smooth surfaces with a texture of 1.6 micrometres 63microinches or fi
26、ner, as defined in ASME B 46.1.6.2 Strain GagesAs a minimum, use two electrical resis-tance strain gages to monitor the strain development in the steelring. Each strain gage shall be wired in a quarter-bridgeconfiguration (that is, one leg of a full Wheatstone bridge). SeeNote 1 for additional infor
27、mation.6.3 Data Acquisition SystemThe data acquisition systemshall be compatible with the strain instrumentation and auto-matically record each strain gage independently. The resolutionof the system shall be 60.0000005 m/m in./in. The systemshall be capable of recording strain data at intervals not
28、toexceed 30 minutes.NOTE 1Use of a precision resistor, to balance the leg of the bridge, astrain conditioner input module, to complete the other half of the bridge,and a 16-channel interface board has been found to adequately provide therequired resolution of the system.6.4 BaseEpoxy-coated plywood
29、or other non-absorptiveand non-reactive surface.6.5 Outer RingUse one of the following alternative ma-terials as the outer ring.6.5.1 PVC PipeSchedule 80-18 PVC pipe, in accordancewith Specification F441/F441M, with a 405 6 3-mm 16.0 60.12-in. inside diameter and 150 6 6-mm 6.0 6 0.25-in.height (see
30、 Fig. 1).6.5.2 Steel Outer Ring3-mm 0.125-in. thick steel sheet-ing formed to obtain a 405 6 3-mm 16.0 6 0.12-in. insidediameter and 150 6 6-mm 6.0 6 0.25-in. height.6.5.3 Other MaterialsOther suitable non-absorptive andnon-reactive materials formed to obtain a 405 6 3-mm 16.0 60.12-in. inside diame
31、ter and 150 6 6-mm 6.0 6 0.25-in.height.6.6 Testing EnvironmentStore the specimens in an envi-ronmentally controlled room with constant air temperature of23.0 6 2.0C 73.5 6 3.5F and relative humidity of 50 64%.7. Materials and Mixing7.1 Materials:7.1.1 CementCement shall conform to SpecificationsC15
32、0/C150M, C595/C595M,orC1157/C1157M.7.1.2 AggregatesAggregates shall conform to Specifica-tion C33/C33M. The maximum nominal size of the coarseaggregate shall be 13 mm 0.5 in. or less.7.2 Mixing:7.2.1 Concrete MixturesMachine mix the concrete asprescribed in Practice C192/C192M.7.2.2 Mortar MixturesM
33、ix the mortar as prescribed inSpecification C387/C387M.5The boldface numbers in parenthesis refer to the list of references at the end ofthis test method.C1581/C1581M 18a28. Properties of Fresh Mixtures8.1 Concrete mixturesSamples of freshly mixed concreteshall be tested in accordance with the follo
34、wing methods:8.1.1 Density (unit weight) and air contentTest MethodC138/C138M.8.1.2 SlumpTest Method C143/C143M.8.2 Mortar MixturesSamples of freshly mixed mortarshall be tested in accordance with the following methods:8.2.1 DensitySpecification C387/C387M.8.2.2 FlowTest Method C1437.FIG. 1 Test Spe
35、cimen Dimensions (Top), Specimen Mold (Bottom Left), and Specimen (Bottom Right).C1581/C1581M 18a39. Specimen Fabrication and Test Setup9.1 Bond two strain gages at midheight locations on theinterior surface of the steel ring along a diameter; that is, mountthe second gage diametrically opposite the
36、 first gage. Orientthe gages to measure strain in the circumferential direction.Follow the manufacturers procedures for mounting and wa-terproofing the gages on the steel ring and connecting lead-wires to the strain gage tabs.9.2 Test Specimen MoldThe test specimen mold consistsof a base, an inner s
37、teel ring and an outer ring.9.2.1 Fabricate a base for each test specimen as described inSection 6.4. The top surface of each base shall minimizefrictional restraint of the specimen.NOTE 2Use of an epoxy coating or a Mylar sheet covering has beenfound to provide a suitable surface between the test s
38、pecimen and thebase.9.2.2 Secure the steel ring to the base before casting usingbolts with eccentric washers (see Fig. 1).9.2.2.1 Coat the outer surface of the steel ring with a releaseagent.9.2.3 Coat the inner surface of the outer ring with a releaseagent.9.2.4 Secure the outer ring to the base to
39、 complete the testspecimen mold using bolts with eccentric washers. Maintain a38 6 1.5-mm 1.50 6 0.06-in. space between the inner steelring and the outer ring (see Fig. 1).9.3 Make and cure at least three test specimens for eachmaterial and test condition following the applicable require-ments of Pr
40、actice C192/C192M. In making a specimen, placethe test specimen mold on a vibrating table, fill the mold in twoapproximately equal layers, rod each layer 75 times using a10-mm 38-in. diameter rod, and vibrate each layer to consoli-date the mixture.9.4 Strike-off the test specimen surface after conso
41、lidation.Finish with the minimum manipulation necessary to achieve aflat surface. Remove any fresh concrete or mortar that hasspilled inside the steel ring or outside the outer ring so that thebase is clean. Transfer the test specimens to the testingenvironment within 10 minutes after completion of
42、casting.9.5 Upon transfer of the test specimens to the testingenvironment, immediately loosen the bolts with eccentricwashers and rotate the washers so they are not in contact withthe steel ring and outer ring. Within 2 minutes after looseningthe bolts with eccentric washers, connect the strain gage
43、lead-wires to the data acquisition system, record the time, andbegin monitoring the strain gages at intervals not greater than30 minutes. Ensure that the strain gage connecting wires areclean of loose material before making the connections. Thetime of the first strain measurement is taken as zero ag
44、e of thespecimen.NOTE 3Monitoring the strain gages soon after casting providesinformation on the internal deformations caused by autogenous shrinkageand heat of hydration (4).9.6 CuringUnless otherwise specified, test specimensshall be moist cured in the molds for 24 h at 23.0 6 2.0C 73.56 3.5F usin
45、g wet burlap covered with polyethylene filmmeeting the requirements of Specification C171. Begin thecuring process within 5 minutes after the first strain reading. Ifthe curing period is longer than 24 h, remove the outer ring at24 h and continue the curing process.9.7 At the end of curing and betwe
46、en strain measurements,prepare the test specimens for drying as follows. Complete thetest specimen preparation within 15 minutes.9.7.1 Remove the outer ring, if it is still in place, and/orremove the polyethylene film and burlap.9.7.2 Gently remove loose material, if present, from the topsurface of
47、the test specimen.9.7.3 Seal the top surface of the test specimen using one ofthe following alternative procedures.NOTE 4With the top surface sealed, and the specimen resting on itsbase, the test specimen dries from the outer circumferential surface only.9.7.3.1 Paraffn WaxCoat the top surface of th
48、e testspecimen with molten paraffin wax. Take precautions to ensurethat the outer circumference of the test specimen is not coatedwith the paraffin wax.NOTE 5Use of a 40-mm 1.5-in. wide brush has been found to be anappropriate means of applying the paraffin wax to the top surface of thetest specimen
49、s.9.7.3.2 Adhesive Aluminum-foil TapeSeal the top surfaceof the test specimen with adhesive aluminum-foil tape.9.7.4 For the calculations outlined subsequently, the agewhen drying is initiated is the time when the first strain readingis made after the test specimens have been sealed.10. Measurement Procedure10.1 Record the time at the start of strain monitoring asstated in Section 9.5.10.2 Record ambient temperature and relative humidity ofthe testing environment every day.10.3 Monitor the strains i
