ASTM C878 C878M-2014a Standard Test Method for Restrained Expansion of Shrinkage-Compensating Concrete《收缩补偿混凝土的约束膨胀性的标准试验方法》.pdf

《ASTM C878 C878M-2014a Standard Test Method for Restrained Expansion of Shrinkage-Compensating Concrete《收缩补偿混凝土的约束膨胀性的标准试验方法》.pdf》由会员分享，可在线阅读，更多相关《ASTM C878 C878M-2014a Standard Test Method for Restrained Expansion of Shrinkage-Compensating Concrete《收缩补偿混凝土的约束膨胀性的标准试验方法》.pdf（5页珍藏版）》请在麦多课文档分享上搜索。

1、Designation: C878/C878M 14aStandard Test Method forRestrained Expansion of Shrinkage-CompensatingConcrete1This standard is issued under the fixed designation C878/C878M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year of l

2、ast revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of the expan-sion of concrete made with shrinkage-compensating cement.1.2 Th

3、e 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 st

4、andard.1.3 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. (Warnin

5、gFreshhydraulic cementitious mixtures 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-gregatesC192/C192M Practice for Making and Curing Concrete TestSpecimens in the

6、LaboratoryC219 Terminology Relating to Hydraulic CementC490 Practice for Use of Apparatus for the Determination ofLength Change of Hardened Cement Paste, Mortar, andConcreteC670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsC806 Test Method for Restra

7、ined Expansion of ExpansiveCement MortarC845 Specification for Expansive Hydraulic Cement2.2 ACI Standards and Committee Reports:4CT ACI Concrete Terminology223R Guide for the Use of Shrinkage-Compensating Con-crete3. Terminology3.1 Terms used in this test method are defined in Terminolo-gies C219 a

8、nd C125.NOTE 1Additional terms not found in Terminologies C219 or C125may be found in ACI CT.4. Significance and Use4.1 Since the potential for expansion, under conditions ofcontrolled restraint, of concrete made with shrinkage-compensating cement cannot always be satisfactorily predictedfrom tests

9、of mortars made in accordance with Test MethodC806, a need has been recognized for a test method in whichconcrete specimens are tested.4.2 This test method can also be adapted readily to studiesof expansion involving degrees of restraint, comparisons ofcements, effects of cement contents, mixture pr

10、oportions,schedules, or environmental treatments that differ from thestandard procedures prescribed by this test method.5. Apparatus5.1 Molds, for casting test specimens, when used in con-junction with the restraining cage described in 4.2, shallprovide for forming prisms 76 mm 3 in. square with a g

11、agelength of 250 mm 10 in. The molds shall otherwise conformto the requirements for molds in Practice C490, except that thestud holder, gage studs, and spacer screws described in thatpractice will not be used.5.2 Restraining Cage, consisting of a threaded low-carbonsteel rod (plain or zinc-coated) w

12、ith steel end plates held inplace by hex nuts as shown in Fig. 1. The hex nuts outside thecage shall be of stainless steel. Stainless steel cap nuts shall beput on each end of the rod. When tested in tension, within the1This method is under the jurisdiction of ASTM Committee C09 on Concreteand Concr

13、ete Aggregates and is the direct responsibility of Subcommittee C09.68on Volume Change.Current edition approved July 1, 2014. Published July 2014. Originally approvedin 1978. Last previous edition approved in 2014 as C878 14. DOI: 10.1520/C0878_C0878M-14A.2Section on Safety Precautions, Manual of Ag

14、gregate 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 AS

15、TM website.4Available from American Concrete Institute (ACI), P.O. Box 9094, FarmingtonHills, MI 48333-9094, http:/www.concrete.org.*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. Uni

16、ted States1elastic range, the rod shall have a strain of 2800 kN 0.0012 60.0001/630 lbf of load (Note 2).NOTE 2It is intended that all rods used meet the indicated requirementfor strain. When a large number of rods are obtained as a single lot,exercise judgment as to whether or not all must be teste

17、d. The designation“10-24” is used in ordinary rods having the desired properties.5.3 Length Comparator, conforming to and to be used inaccordance with the requirements of Practice C490. Use areference bar complying with the description given in PracticeC490. If the terminals of the comparator are fi

18、tted with collars,they shall be such that the cap nuts on the ends of the threadedrod of the specimen do not rest on the collar during themeasuring (see Figs. 2 and 3).5.4 Tamping RodThe tamping rod shall be a straight steelrod, 10 mm 38 in. in diameter, and no less than 250 mm 10in. in length, havi

19、ng at least the tamping end rounded to ahemispherical tip of the same diameter.5.5 Vibrators, conforming to the requirements for externalvibrators prescribed in Practice C192/C192M.MeasurementDimensionsin. mmA11916 116 2941.6B 10 254 (gage length)C3 7D23132 132 751E112 38F13164 37.7G38 10H316 5NOTE

20、1All material is mild steel, except for stainless steel cap nuts.FIG. 1 Restraining CageC878/C878M 14a26. Test Specimen6.1 The test specimen shall be a prism: 75 mm 3 in. squarewith a gage length of 250 mm 10 in. and an overall length(including the length of the rod and cap nuts) of approximately290

21、 mm 11.5 in. At least three specimens shall be preparedfor each test.NOTE 3Use of aggregates of nominal maximum size greater than 25.0mm 1 in. may adversely affect the test results.7. Preparation and Assembly of Specimen Molds andRestaining Cage7.1 Install the cap nuts firmly in place on the ends of

22、 therestraining rods using a suitable adhesive to keep them fromloosening when comparator readings are made (Note 4). Thecap nuts should not be removed after the initial comparatorreading of a specimen is made. Measure the restraining cageassembly length, including the cap nuts, while it is at 23.0

23、6 2C 73.5 6 3.5 F. This is to ensure it is 30 6 2mm119166116 in. The measurement taken at this time is used only toensure that comparator readings can be made.NOTE 4A rapid-setting epoxy has been found suitable.7.2 Thinly cover the edges of the restraining cage end platesthat contact the sides and b

24、ottom of the mold with a heavymineral oil or light cup grease such as petrolatum. Afterassembly of the molds, place a restraining cage in each moldcompartment. Seal the contact lines between the outer sidesand base plate of the molds with paraffin or micro-crystallinewax. Thinly cover the interior f

25、aces of the molds with mineraloil and remove any oil or grease from the restraining cage rodand end plates.8. Procedure8.1 Preparation and Mixing of MaterialsMixtures usingjob materials shall be made in the laboratory as described inPractice C192/C192M, except that the material temperaturesshall be

26、approximately those anticipated in the field. Mixingprocedures shall also reflect the actual mixing and deliverytimes expected for the particular work. Remove aggregateretained on the 25.0 mm 1 in. sieve from that used in themixture from which the specimens are to be molded. Select themixture propor

27、tions according to applicable provisions of223R.8.2 Molding SpecimensPlace the concrete in the mold intwo approximately equal layers (the first layer shall just coverFIG. 2 Schematic of Upper and Lower Adjustable Restraining Collar for Length Comparator that Will Allow Positioning of RestrainingCage

28、 Cap Nuts to Rest on Anvils Without Interference from the CollarsFIG. 3 Cross Section of Restraining Collar Showing Positioningof Cap Nut for MeasurementC878/C878M 14a3the threaded restraining rod) in accordance with the generalinstructions given for placing concrete in specimen moldsgiven in Practi

29、ce C192/C192M. Consolidate each layer byrodding or by external vibration in accordance with theinstructions for consolidation of flexure test specimens given inPractice C192/C192M, except use the same method of consoli-dation for all specimens to be compared. The top layer shallslightly overfill the

30、 mold. After consolidation is complete,strike off the excess material with a straightedge and finish theexposed surface with a few strokes of a straight-edged trowel.8.3 Curing SpecimensCover the specimens with a poly-ethylene sheet or other suitable material to prevent loss or gainof moisture at th

31、e surface of the specimens.8.4 Remove the specimens from the molds at the age of 6 h.In unusual cases the specimens may not be strong enough todemold at the age of 6 h. If this is the case, select a later timebut demold as soon as practicable and report the demolding agewith the results. Remove the

32、specimens from the molds byloosening or removing the mold-fastening devices and gentlytapping the base plate and side plates so as to free them fromthe specimens. Exercise great care in this operation, because ofthe fragility of the concrete at this age and in all later handlingof specimens. Do not

33、place specimens directly on hard wood ormetal table tops. Placing a soft rubber mat over table tops tolessen impact force on specimens has been found to reducescatter in data. Limit any marks placed on the specimens foridentification or positioning to those made by graphite appliedeither by a soft p

34、encil or as a liquid that deposits essentiallygraphite without binder, to those made with waterproof indel-ible ink, or to light scratchings in the surface of the concretemade with a sharp instrument.8.5 Measuring SpecimensTake the initial comparatorreadings 30 6 2 min after demolding. After the ini

35、tialcomparator reading, cure the specimens in lime-saturated waterat 23 6 2 C 73.5 6 3.5 F until they have reached an age of7 days.At the end of the curing period take another comparatorreading. It is permitted for comparator readings to be taken atintermediate ages between the initial comparator re

36、ading andthe comparator reading at 7 days (Note 5).NOTE 5It is permitted to provide further water-curing, or alternativelythe specimens shall be allowed to air-dry under any desired condition inorder to determine later age length change data. Comparator readings shallbe taken at any appropriate inte

37、rval.9. Calculation9.1 Calculate the length changes as percent expansion orshrinkage as follows:Length change, % 5 corrected comparator reading (1)2corrected initial comparator reading)/gage length#3100where the corrected comparator reading is equal to thespecimen comparator reading minus the refere

38、nce bar com-parator reading.10. Report10.1 Report the following information:10.1.1 Identification of specimens, number of specimens foreach condition, and date molded,10.1.2 Source and identification of each material employed,10.1.3 Type, nominal maximum size, moisture condition,and proportions of e

39、ach aggregate used,10.1.4 Concrete mixture data,10.1.5 Consolidation method, whether rodding or externalvibration was used,10.1.6 Conditions and periods of moist curing prior to andsubsequent to removal of molds, if different from thosespecified.10.1.7 Description of storage conditions,10.1.8 Total

40、length of the period of storage and total age ofthe specimen, or total length of curing and storage if the samecondition was used for both, for each observation, and10.1.9 Report length change data, in % , recorded as linearexpansion during moist-curing and moist storage and as linearcontraction dur

41、ing dry storage both based on the initialcomparator reading made at the time of removal from themolds, as the average percent change in linear dimension to thenearest 0.001 %.10.1.10 Any other pertinent information.11. Precision and Bias11.1 Precision:11.1.1 The following precision statements are ap

42、plicablewhen a test result is the average percent restrained expansion of3 prisms molded from a single batch of concrete and tested atthe same age. It is applicable for concrete made from Type K,Type S, or Type M shrinkage-compensating cements (C845)and tested at 3, 7, or 28 days.11.2 The multilabor

43、atory standard deviation has been foundto be 0.015 % expansion. Therefore, the results of properlyconducted tests of a single batch by two different laboratoriesshould not differ from each other by more than 0.043 %5.11.3 Data necessary to determine single-laboratory preci-sion are not available at

44、this time.11.4 BiasData to determine bias are not available; nostandards are known to exist.12. Keywords12.1 expansion; restrained expansion; shrinkage compensat-ing concrete5These numbers represent, respectively, the (1s) ands (d2s) limits as described inPractice C670.C878/C878M 14a4SUMMARY OF CHAN

45、GESCommittee C09 has identified the location of selected changes to this standard since the last issue (C878 14)that may impact the use of this standard. (Approved July 1, 2014.)(1) Revised Section 3.Committee C09 has identified the location of selected changes to this standard since the last issue(

46、C878/C878M 09) that may impact the use of this standard. (Approved Jan. 1, 2014.)(1) Revised ACI Standards in 2.2, as well as references in 3.1and 8.1.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Use

47、rs of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every

48、 five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technic

49、al committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.or