1、Designation: C 1581/C 1581M 09aStandard Test Method forDetermining Age at Cracking and Induced Tensile StressCharacteristics of Mortar and Concrete under RestrainedShrinkage1This standard is issued under the fixed designation C 1581/C 1581M; the number immediately following the designation indicates
2、 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 test method covers the laboratory determi
3、nation 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 a
4、nd deformationscaused 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; theref
5、ore, 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
6、 to establish appro-priate safety and health practices and to determine theapplicability of regulatory limitations prior to use.(WarningFresh hydraulic cementitious mixtures are causticand may cause chemical burns to skin and tissue uponprolonged exposure.2)2. Referenced Documents2.1 ASTM Standards:
7、3C33 Specification for Concrete AggregatesC 138/C 138M Test Method for Density (Unit Weight),Yield, and Air Content (Gravimetric) of ConcreteC 143/C 143M Test Method for Slump of Hydraulic-Cement ConcreteC 150 Specification for Portland CementC 171 Specification for Sheet Materials for Curing Concre
8、teC 192/C 192M Practice for Making and Curing ConcreteTest Specimens in the LaboratoryC 387 Specification for Packaged, Dry, Combined Materialsfor Mortar and ConcreteC 595 Specification for Blended Hydraulic CementsC 1157 Performance Specification for Hydraulic CementC 1437 Test Method for Flow of H
9、ydraulic Cement MortarF 441/F 441M Specification for Chlorinated Poly(VinylChloride) (CPVC) Plastic Pipe, Schedules 40 and 802.2 ASME Standards:4B 46.1 Surface Texture (Surface Roughness, Waviness andLay)3. Summary of Test Method3.1 A sample of freshly mixed mortar or concrete is com-pacted in a cir
10、cular 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)5. Cracking of the test specimen isindicated by a sudden decrease in the steel ring strain. The ageat crackin
11、g and the rate of tensile stress development in the testspecimen are indicators of the materials resistance to crackingunder restrained shrinkage.4. Significance and Use4.1 This test method is for relative comparison of materialsand is not intended to determine the age at cracking of mortaror concre
12、te in any specific type of structure, configuration, orexposure.4.2 This test method is applicable to mixtures with aggre-gates of 13-mm 0.5-in. maximum nominal size or less.4.3 This test method is useful for determining the relativelikelihood of early-age cracking of different cementitiousmixtures
13、and for aiding in the selection of cement-based1This 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 edition approved July 1, 2009. Published August 2009. Originallyapproved
14、 in 2004. Last previous edition approved in 2009 as C 1581 09.2Section 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.
15、For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Available from American Society of Mechanical Engineers (ASME), ASMEInternational Headquarters, Three Park Ave., New York, NY 10016-5990, http:/www.asme.org.5The boldface numbers in
16、parenthesis refer to the list of references at the end ofthis test method1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.materials that are less likely to crack under
17、retrained shrinkage.Actual cracking tendency in service depends on many variablesincluding type of structure, degree of restraint, rate of propertydevelopment, construction and curing methods, and environ-mental conditions.4.4 This test method can be used to determine the relativeeffects of material
18、 variations on induced tensile stresses andcracking potential. These variations can include, but are notlimited to, aggregate source, aggregate gradation, cement type,cement content, water content, supplementary cementing ma-terials, or chemical admixtures.4.5 For materials that have not cracked dur
19、ing the test, therate of tensile stress development at the time the test isterminated provides a basis for comparison of the materials.5. Apparatus5.1 Steel ringStructural steel pipe with a wall thickness of13 6 1 mm 0.50 6 0.05 in., an outside diameter of 330 6 3mm 13.0 6 0.12 in. and a height of 1
20、50 6 6 mm 6.0 6 0.25in. (see Fig. 1). Machine the inner and outer faces to producesmooth surfaces with a texture of 1.6 micrometres 63 micro-inches or finer, as defined in ASME B 46.1.5.2 Strain gagesAs a minimum, use two electrical resis-tance strain gages to monitor the strain development in the s
21、teelring. Each strain gage shall be wired in a quarter-bridgeconfiguration (that is, one leg of a full Wheatstone bridge). SeeNote 1 for additional information.5.3 Data acquisition systemThe data acquisition systemshall be compatible with the strain instrumentation and auto-matically record each str
22、ain 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 toexceed 30 minutes.NOTE 1Use of a precision resistor, to balance the leg of the bridge, astrain conditioner input module, to complete the other ha
23、lf of the bridge,and a 16-channel interface board has been found to adequately provide therequired resolution of the system.5.4 BaseEpoxy-coated plywood or other non-absorptiveand non-reactive surface.5.5 Outer ringUse one of the following alternative mate-rials as the outer ring.5.5.1 PVC pipeSched
24、ule 80-18 PVC pipe, in accordancewith Specification F 441/F 441M, 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 Fig. 1).5.5.2 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
25、.0 6 0.25-in. height.5.5.3 Other materialsOther suitable non-absorptive andnon-reactive materials formed to obtain a 405 6 3-mm 16.0 60.12-in. inside diameter and 150 6 6-mm 6.0 6 0.25-in.height.5.6 Testing environmentStore the specimens in an envi-ronmentally controlled room with constant air tempe
26、rature of23.0 6 2.0 C 73.5 6 3.5 F and relative humidity of 50 64%.6. Materials and Mixing6.1 Materials:6.1.1 CementCement shall conform to SpecificationsC 150, C 595, or C 1157.6.1.2 AggregatesAggregates shall conform to Specifica-tion C33. The maximum nominal size of the coarse aggregateshall be 1
27、3 mm 0.5 in. or less.6.2 Mixing:6.2.1 Concrete mixturesMachine mix the concrete asprescribed in Practice C 192/C 192M.6.2.2 Mortar mixturesMix the mortar as prescribed inSpecification C 387.7. Properties of Fresh Mixtures7.1 Concrete mixturesSamples of freshly mixed concreteshall be tested in accord
28、ance with the following methods:7.1.1 Density (unit weight) and air contentTest MethodC 138/C 138M.7.1.2 SlumpTest Method C 143/C 143M.7.2 Mortar mixturesSamples of freshly mixed mortarshall be tested in accordance with the following methods:7.2.1 DensitySpecification C 387.7.2.2 FlowTest Method C 1
29、437.8. Specimen Fabrication and Test Setup8.1 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 first gage. Orientthe gages to measure strain in the circumferential direction.Follow the man
30、ufacturers procedures for mounting and wa-terproofing the gages on the steel ring and connecting lead-wires to the strain gage tabs.8.2 Test specimen moldThe test specimen mold consistsof a base, an inner steel ring and an outer ring.8.2.1 Fabricate a base for each test specimen as described inSecti
31、on 5.4. 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 specimen and thebase.8.2.2 Secure the steel ring to the base before casting usingbolts with ecc
32、entric washers (see Fig. 1).8.2.2.1 Coat the outer surface of the steel ring with a releaseagent.8.2.3 Coat the inner surface of the outer ring with a releaseagent.8.2.4 Secure the outer ring to the base to complete the testspecimen mold using bolts with eccentric washers. Maintain a38 6 1.5-mm 1.50
33、 6 0.06-in. space between the inner steelring and the outer ring (see Fig. 1).8.3 Make and cure at least three test specimens for eachmaterial and test condition following the applicable require-ments of Practice C 192/C 192 M. In making a specimen, placethe test specimen mold on a vibrating table,
34、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.8.4 Strike-off the test specimen surface after consolidation.Finish with the minimum manipulation necessary to achieve aflat surface. Remove an
35、y fresh concrete or mortar that hasC 1581/C 1581M 09a2spilled 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 casting.8.5 Upon transfer of the test specimens to the testingenvironmen
36、t, 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 gagelead-wires to the data acquisition system, record the time, andbegin mon
37、itoring the strain gages at intervals not greater thanFIG. 1 Test specimen dimensions (top), specimen mold (bottom left), and specimen (bottom right).C 1581/C 1581M 09a330 minutes. Ensure that the strain gage connecting wires areclean of loose material before making the connections. Thetime of the f
38、irst strain measurement is taken as zero age of thespecimen.NOTE 3Monitoring the strain gages soon after casting providesinformation on the internal deformations caused by autogenous shrinkageand heat of hydration (4).8.6 CuringUnless otherwise specified, test specimensshall be moist cured in the mo
39、lds for 24 h at 23.0 6 2.0 C73.5 6 3.5 F using wet burlap covered with polyethylenefilm meeting the requirements of Specification C 171. Beginthe curing process within 5 minutes after the first strainreading. If the curing period is longer than 24 h, remove theouter ring at 24 h and continue the cur
40、ing process.8.7 At the end of curing and between strain measurements,prepare the test specimens for drying as follows. Complete thetest specimen preparation within 15 minutes.8.7.1 Remove the outer ring, if it is still in place, and/orremove the polyethylene film and burlap.8.7.2 Gently remove loose
41、 material, if present, from the topsurface of the test specimen.8.7.3 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
42、.8.7.3.1 Paraffn waxCoat the top surface of the 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 paraf
43、fin wax to the top surface of thetest specimens.8.7.3.2 Adhesive aluminum-foil tapeSeal the top surfaceof the test specimen with adhesive aluminum-foil tape.8.7.4 For the calculations outlined subsequently, the agewhen drying is initiated is the time when the first strain readingis made after the te
44、st specimens have been sealed.9. Measurement Procedure9.1 Record the time at the start of strain monitoring as statedin Section 8.5.9.2 Record ambient temperature and relative humidity ofthe testing environment every day.9.3 Monitor the strains in the steel rings at intervals not toexceed 30 minutes
45、, recording the output of each strain gageseparately with the data acquisition system. Record both thetime and the strain at each measurement. A sudden decrease incompressive strain in one or both strain gages indicatescracking (see Note 6) (1-5). Review the strain measurementsand visually inspect t
46、he specimens for cracking at timeintervals not greater than 3 days.NOTE 6The sudden decrease in compressive strain at cracking isusually greater than 30 microstrains (see Fig. 2).9.4 Monitor and record the strain in the steel rings for atleast 28 days after initiation of drying, unless cracking occu
47、rsprior to 28 days.9.5 Plot the steel ring strain for each strain gage againstspecimen age (see Fig. 2).10. Calculation10.1 Age at crackingDetermine the age at cracking as theage of each test specimen (measured from the time of casting)when a sudden decrease in strain occurs. Report the age atcracki
48、ng to the nearest 0.25 day. If a test specimen does notFIG. 2 Steel ring strain versus specimen age.C 1581/C 1581M 09a4crack within the duration of the test, report the result as “nocracking” and record the age when the test was terminated.10.1.1 Average age at crackingCalculate the average ageat cr
49、acking for the test specimens to the nearest day.10.2 Initial strainFrom the time-strain data for each straingage, record the initial strain as the strain corresponding to theage when drying was initiated (see Fig. 2).10.2.1 Average initial strainCalculate the average initialstrain for the test specimens.NOTE 7The average initial strain indicates the net effect of deforma-tions caused by early-age autogenous shrinkage and heat of hydrationunder the restrained conditions (4).10.3 Maximum strainFro
