1、Designation: C1581/C1581M 09aC1581/C1581M 16Standard 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 designatio
2、n 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 test method covers the laborat
3、ory determination of the age at cracking and induced tensile stress characteristics ofmortar or concrete specimens under restrained shrinkage. The procedure can be used to determine the effects of variations in theproportions and material properties of mortar or concrete on cracking due to both dryi
4、ng shrinkage and deformations caused byautogenous 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 units are to be regarded separately as standard. The values stated in eachsystem may not be exact equi
5、valents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the use
6、r of this standard to establish appropriate safety and health practices and to determine the applicability of regulatorylimitations prior to use. (WarningFresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin andtissue upon prolonged exposure.2)2. Referenced Documents
7、2.1 ASTM Standards:3C33C33/C33M Specification for Concrete AggregatesC125 Terminology Relating to Concrete and Concrete AggregatesC138/C138M Test Method for Density (Unit Weight), Yield, and Air Content (Gravimetric) of ConcreteC143/C143M Test Method for Slump of Hydraulic-Cement ConcreteC150C150/C1
8、50M Specification for Portland CementC171 Specification for Sheet Materials for Curing ConcreteC192/C192M Practice for Making and Curing Concrete Test Specimens in the LaboratoryC387C387/C387M Specification for Packaged, Dry, Combined Materials for Mortar and ConcreteConcrete and High StrengthMortar
9、C595C595/C595M Specification for Blended Hydraulic CementsC1157C1157/C1157M Performance Specification for Hydraulic CementC1437 Test Method for Flow of Hydraulic Cement MortarF441/F441M Specification for Chlorinated Poly(Vinyl Chloride) (CPVC) Plastic Pipe, Schedules 40 and 802.2 ASME Standards:4B 4
10、6.1 Surface Texture (Surface Roughness, Waviness and Lay)1 This test method is under the jurisdiction of ASTM Committee C09 on Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee C09.68 onVolume Change.Current edition approved July 1, 2009July 1, 2016. Published August
11、2009August 2016. Originally approved in 2004. Last previous edition approved in 2009 asC1581 09.C1581 09a. DOI: 10.1520/C1581_C1581M-09A.10.1520/C1581_C1581M-16.2 Section on Safety Precautions, Manual of Aggregate and Concrete Testing , Annual Book of ASTM Standards, Vol 04.02.3 For referencedASTM s
12、tandards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.4 Available from American Society of Mechanical Engineers (ASME), ASME Internationa
13、l Headquarters, Three Park Ave., New York, NY 10016-5990, http:/www.asme.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequatel
14、y depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM Inter
15、national, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method, refer to Terminology C125.3.2 Definitions of Terms Specific to This Standard:3.2.1 age at cracking, nthe age of each te
16、st specimen, measured from the time of casting, when a sudden decrease in strainoccurs.3.2.2 net strain, nthe value corresponding to the difference between the strain in the steel ring at each recorded time and theinitial strain.4. Summary of Test Method4.1 A sample of freshly mixed mortar or concre
17、te is compacted in a circular mold around an instrumented steel ring. Thecompressive strain developed in the steel ring caused by shrinkage of the mortar or concrete specimen is measured from the timeof casting (1-6).5 Cracking of the test specimen is indicated by a sudden decrease in the steel ring
18、 strain. The age at cracking andthe rate of tensile stress development in the test specimen are indicators of the materials resistance to cracking under restrainedshrinkage.5. Significance and Use5.1 This test method is for relative comparison of materials and is not intended to determine the age at
19、 cracking of mortar orconcrete in any specific type of structure, configuration, or exposure.5.2 This test method is applicable to mixtures with aggregates of 13-mm 0.5-in. maximum nominal size or less.5.3 This test method is useful for determining the relative likelihood of early-age cracking of di
20、fferent cementitious mixturesand for aiding in the selection of cement-based materials that are less likely to crack under retrained shrinkage. Actual crackingtendency in service depends on many variables including type of structure, degree of restraint, rate of property development,construction and
21、 curing methods, and environmental conditions.5.4 This test method can be used to determine the relative effects of material variations on induced tensile stresses and crackingpotential. These variations can include, but are not limited to, aggregate source, aggregate gradation, cement type, cement
22、content,water content, supplementary cementing materials, or chemical admixtures.5.5 For materials that have not cracked during the test, the rate of tensile stress development at the time the test is terminatedprovides a basis for comparison of the materials.6. Apparatus6.1 Steel ringStructural ste
23、el pipe with a wall thickness of 13 6 1 mm 0.50 6 0.05 in., an outside diameter of 330 6 3 mm13.0 6 0.12 in. and a height of 150 6 6 mm 6.0 6 0.25 in. (see Fig. 1). Machine the inner and outer faces to produce smoothsurfaces with a texture of 1.6 micrometres 63 microinches or finer, as defined in AS
24、ME B 46.1.6.2 Strain gagesAs a minimum, use two electrical resistance strain gages to monitor the strain development in the steel ring.Each strain gage shall be wired in a quarter-bridge configuration (that is, one leg of a full Wheatstone bridge). See Note 1 foradditional information.6.3 Data acqui
25、sition systemThe data acquisition system shall be compatible with the strain instrumentation and automaticallyrecord each strain gage independently.The resolution of the system shall be60.0000005 m/m in./in.The system shall be capableof recording strain data at intervals not to exceed 30 minutes.NOT
26、E 1Use of a precision resistor, to balance the leg of the bridge, a strain conditioner input module, to complete the other half of the bridge, anda 16-channel interface board has been found to adequately provide the required resolution of the system.6.4 BaseEpoxy-coated plywood or other non-absorpti
27、ve and non-reactive surface.6.5 Outer ringUse one of the following alternative materials as the outer ring.6.5.1 PVC pipeSchedule 80-18 PVC pipe, in accordance with 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 Fig. 1).6.5.2 Stee
28、l outer ring3-mm 0.125-in. thick steel sheeting formed to obtain a 405 6 3-mm 16.0 6 0.12-in. inside diameterand 150 6 6-mm 6.0 6 0.25-in. height.6.5.3 Other materialsOther suitable non-absorptive and non-reactive materials formed to obtain a 405 6 3-mm 16.0 60.12-in. inside diameter and 150 6 6-mm
29、6.0 6 0.25-in. height.6.6 Testing environmentStore the specimens in an environmentally controlled room with constant air temperature of 23.0 62.0 C 73.5 6 3.5 F and relative humidity of 50 6 4 %.5 The boldface numbers in parenthesis refer to the list of references at the end of this test method.C158
30、1/C1581M 1627. Materials and Mixing7.1 Materials:7.1.1 CementCement shall conform to Specifications C150C150/C150M, C595C595/C595M, or C1157C1157/C1157M.7.1.2 AggregatesAggregates shall conform to Specification C33C33/C33M. The maximum nominal size of the coarseaggregate shall be 13 mm 0.5 in. or le
31、ss.FIG. 1 Test specimen dimensions (top), specimen mold (bottom left), and specimen (bottom right).C1581/C1581M 1637.2 Mixing:7.2.1 Concrete mixturesMachine mix the concrete as prescribed in Practice C192/C192M.7.2.2 Mortar mixturesMix the mortar as prescribed in Specification C387C387/C387M.8. Prop
32、erties of Fresh Mixtures8.1 Concrete mixturesSamples of freshly mixed concrete shall be tested in accordance with the following methods:8.1.1 Density (unit weight) and air contentTest Method C138/C138M.8.1.2 SlumpTest Method C143/C143M.8.2 Mortar mixturesSamples of freshly mixed mortar shall be test
33、ed in accordance with the following methods:8.2.1 DensitySpecification C387C387/C387M.8.2.2 FlowTest Method C1437.9. Specimen Fabrication and Test Setup9.1 Bond two strain gages at midheight locations on the interior surface of the steel ring along a diameter; that is, mount thesecond gage diametric
34、ally opposite the first gage. Orient the gages to measure strain in the circumferential direction. Follow themanufacturers procedures for mounting and waterproofing the gages on the steel ring and connecting lead-wires to the strain gagetabs.9.2 Test specimen moldThe test specimen mold consists of a
35、 base, an inner steel ring and an outer ring.9.2.1 Fabricate a base for each test specimen as described in Section 5.46.4. The top surface of each base shall minimizefrictional restraint of the specimen.NOTE 2Use of an epoxy coating or a Mylar sheet covering has been found to provide a suitable surf
36、ace between the test specimen and the base.9.2.2 Secure the steel ring to the base before casting using bolts with eccentric washers (see Fig. 1).9.2.2.1 Coat the outer surface of the steel ring with a release agent.9.2.3 Coat the inner surface of the outer ring with a release agent.9.2.4 Secure the
37、 outer ring to the base to complete the test specimen mold using bolts with eccentric washers. Maintain a 386 1.5-mm 1.50 6 0.06-in. space between the inner steel ring and the outer ring (see Fig. 1).9.3 Make and cure at least three test specimens for each material and test condition following the a
38、pplicable requirements ofPractice C192/C192M. In making a specimen, place the test specimen mold on a vibrating table, fill the mold in two approximatelyequal layers, rod each layer 75 times using a 10-mm 38-in. diameter rod, and vibrate each layer to consolidate the mixture.9.4 Strike-off the test
39、specimen surface after consolidation. Finish with the minimum manipulation necessary to achieve a flatsurface. Remove any fresh concrete or mortar that has spilled inside the steel ring or outside the outer ring so that the base is clean.Transfer the test specimens to the testing environment within
40、10 minutes after completion of casting.9.5 Upon transfer of the test specimens to the testing environment, immediately loosen the bolts with eccentric washers androtate the washers so they are not in contact with the steel ring and outer ring. Within 2 minutes after loosening the bolts witheccentric
41、 washers, connect the strain gage lead-wires to the data acquisition system, record the time, and begin monitoring thestrain gages at intervals not greater than 30 minutes. Ensure that the strain gage connecting wires are clean of loose material beforemaking the connections. The time of the first st
42、rain measurement is taken as zero age of the specimen.NOTE 3Monitoring the strain gages soon after casting provides information on the internal deformations caused by autogenous shrinkage and heatof hydration (4).9.6 CuringUnless otherwise specified, test specimens shall be moist cured in the molds
43、for 24 h at 23.0 6 2.0 C 73.5 63.5 F using wet burlap covered with polyethylene film meeting the requirements of Specification C171. Begin the curing processwithin 5 minutes after the first strain reading. If the curing period is longer than 24 h, remove the outer ring at 24 h and continuethe curing
44、 process.9.7 At the end of curing and between strain measurements, prepare the test specimens for drying as follows. Complete the testspecimen preparation within 15 minutes.9.7.1 Remove the outer ring, if it is still in place, and/or remove the polyethylene film and burlap.9.7.2 Gently remove loose
45、material, if present, from the top surface of the test specimen.9.7.3 Seal the top surface of the test specimen using one of the following alternative procedures.NOTE 4With the top surface sealed, and the specimen resting on its base, the test specimen dries from the outer circumferential surface on
46、ly.9.7.3.1 Paraffn waxCoat the top surface of the test specimen with molten paraffin wax. Take precautions to ensure that theouter circumference of the test specimen is not coated with the paraffin wax.NOTE 5Use of a 40-mm 1.5-in. wide brush has been found to be an appropriate means of applying the
47、paraffin wax to the top surface of the testspecimens.9.7.3.2 Adhesive aluminum-foil tapeSeal the top surface of the test specimen with adhesive aluminum-foil tape.C1581/C1581M 1649.7.4 For the calculations outlined subsequently, the age when drying is initiated is the time when the first strain read
48、ing is madeafter the test specimens have been sealed.10. Measurement Procedure10.1 Record the time at the start of strain monitoring as stated in Section 8.59.5.10.2 Record ambient temperature and relative humidity of the testing environment every day.10.3 Monitor the strains in the steel rings at i
49、ntervals not to exceed 30 minutes, recording the output of each strain gageseparately with the data acquisition system. Record both the time and the strain at each measurement. A sudden decrease incompressive strain in one or both strain gages indicates cracking (see Note 6) (1-5). Review the strain measurements and visuallyinspect the specimens for cracking at time intervals not greater than 3 days.NOTE 6The sudden decrease in compressive strain at cracking is usually greater than 30 microstrain
