ASTM C878 C878M-2003 Standard Test Method for Restrained Expansion of Shrinkage-Compensating Concrete.pdf

1、Designation: C 878/C 878M 03Standard Test Method forRestrained Expansion of Shrinkage-CompensatingConcrete1This standard is issued under the fixed designation C 878/C 878M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the year o

2、f last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the expan-sion of concrete made with shrinkage-compensating cement.1.2

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, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the

4、 standard.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.2. Re

5、ferenced Documents2.1 ASTM Standards:C 125 Terminology Relating to Concrete and ConcreteAggregates2C 157/C 157M Test Method for Length Change of Hard-ened Hydraulic Cement, Mortar, and Concrete2C 192/C 192M Practice for Making and Curing ConcreteTest Specimens in the Laboratory2C 219 Terminology Rel

6、ating to Hydraulic Cement3C 403/C 403M Test Method for Time of Setting of ConcreteMixtures by Penetration Resistance2C 490 Practice for Use of Apparatus for the Determinationof Length Change of Hardened Cement Paste, Mortar, andConcrete3C 670 Practice for Preparing Precision and Bias Statementsfor T

7、est Methods for Construction Materials2C 806 Test Method for Restrained Expansion of ExpansiveCement Mortar3C 845 Specification for Expansive Hydraulic Cement32.2 ACI Standards and Committee Reports:4116-R-90 Cement and Concrete Terminology223-83 Standard Practice for the Use of Shrinkage-Compensati

8、ng Concrete3. Terminology3.1 Terms used in this test method are defined in Terminol-ogy C 219, Terminology C 125, and ACI 116-R-90.4. Significance and Use4.1 Since the potential for expansion, under conditions ofcontrolled restraint, of concrete made with shrinkage-compensating cement cannot always

9、be satisfactorily predictedfrom tests of mortars made in accordance with Test MethodC 806, 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,

10、 effects of cement contents, mixture proportions,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 for

11、ming prisms 76 mm 3 in. square with a gagelength of 250 mm 10 in. The molds shall otherwise conformto the requirements for molds in Practice C 490, 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-

12、carbonsteel rod (plain or zinc-coated) with 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 theelastic range, the rod shall have a strai

13、n of 2800 kN 0.0012 60.0001/630 lbf of load (Note 1).NOTE 1It is intended that all rods used meet the indicated requirement1This method is under the jurisdiction of ASTM Committee C09 on Concreteand Concrete Aggregates and is the direct responsibility of SubcommitteeC09.68 on Volume Change.Current e

14、dition approved Jan. 10, 2003. Published April 2003. Originallyapproved in 1978. Last previous edition approved in 1995 as C 87895a.2Annual Book of ASTM Standards, Vol 04.02.3Annual Book of ASTM Standards, Vol 04.01.4Available from American Concrete Institute (ACI), P.O. Box 9094, FarmingtonHills, M

15、I 48333.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.for strain. When a large number of rods are obtained as a single lot,exercise judgment as to whether or not all must be tested. The designation“10-24” is used in ordinary rods h

16、aving the desired properties.5.3 Length Comparator, conforming to and to be used inaccordance with the requirements of Practice C 490. Use areference bar complying with the description given in PracticeC 490. If the terminals of the comparator are fitted with collars,they shall be such that the cap

17、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 38in. in diameter, and no less than 250 mm 10in. in length, having at least the tamping end rounded to ahemispheric

18、al tip of the same diameter.5.5 Vibrators, conforming to the requirements for externalvibrators prescribed in Practice C 192/C 192M.6. 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

19、cap nuts) of approximately290 mm 11.5 in. At least three specimens shall be preparedfor each test.MeasurementDimensionsin. mmA119166116 294 6 1.6B 10 254 (gage length)C3 7D231326132 75 6 1E112 38F13164 37.7G38 10H316 5NOTE 1All material is mild steel, except for stainless steel cap nuts.FIG. 1 Restr

20、aining CageC 878/C 878M 032NOTE 2Use 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 therestraining rods using a suitable adhe

21、sive to keep them fromloosening when comparator readings are made (Note 3). 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 62C 73.5 6 3.5F. This is to ensure it is 3

22、0 6 2mm119166116 in. The measurement taken at this time is used only toensure that comparator readings can be made.NOTE 3A rapid-setting epoxy has been found suitable.7.2 Thinly cover the edges of the restraining cage end platesthat contact the sides and bottom of the mold with a heavymineral oil or

23、 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 faces of the molds with mineraloil and remove

24、 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 C 192/C 192M, except that the material temperaturesshall be approximately those anticipated in the fie

25、ld. 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 proportions according to applicable provisions o

26、f ACI223.8.2 Molding SpecimensPlace the concrete in the mold intwo approximately equal layers (the first layer shall just coverthe threaded restraining rod) in accordance with the generalinstructions given for placing concrete in specimen moldsgiven in Practice C 192/C 192M. Consolidate each layer b

27、yrodding or by external vibration in accordance with theFIG. 2 Schematic of Upper and Lower Adjustable Restraining Collar for Length Comparator that Will Allow Positioning of RestrainingCage Cap Nuts to Rest on Anvils Without Interference from the CollarsFIG. 3 Cross Section of Restraining Collar Sh

28、owing Positioningof Cap Nut for MeasurementC 878/C 878M 033instructions for consolidation of flexure test specimens given inPractice C 192/C 192M, except use the same method of con-solidation for all specimens to be compared. The top layer shallslightly overfill the mold. After consolidation is comp

29、lete,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 the surface of the specimens.8.4 Rem

30、ove 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 specimens from the molds bylooseni

31、ng 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 place specimens directly on hard w

32、ood 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 pencil or as a liquid that deposits

33、 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 initialcomparator reading, cure the s

34、pecimens in lime-saturated waterat 23 6 2C 73.5 6 3.5F 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 reading andthe comparator reading at

35、7 days (Note 4).NOTE 4It 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 interval.9. Calculation9.1 Calculate th

36、e length changes as percent expansion orshrinkage as follows:Length change, % 5corrected comparator reading2 corrected initial comparator reading!/gage length#3100(1)where the corrected comparator reading is equal to thespecimen comparator reading minus the reference bar com-parator reading.10. Repo

37、rt10.1 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 each aggregate used,10.1.4 Concrete m

38、ixture 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 length of the period of storage and

39、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 during dry storage both based on the in

40、itialcomparator 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 applicablewhen a test result is the av

41、erage 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 (C 845)and tested at 3, 7, or 28 days.11.2 The multilaboratory standard deviation has been f

42、oundto 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 this time.11.4 BiasData to determin

43、e 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 C 670.C 878/C 878M 034ASTM International takes no position respecting

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47、 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.org (e-mail); or through the ASTM website(www.astm.org).C 878/C 878M 035