ASTM C490 C490M-2009 Standard Practice for Use of Apparatus for the Determination of Length Change of Hardened Cement Paste Mortar and Concrete《硬化水泥浆、灰浆和混凝土长度变化测定用仪器使用的标准实施规程》.pdf

《ASTM C490 C490M-2009 Standard Practice for Use of Apparatus for the Determination of Length Change of Hardened Cement Paste Mortar and Concrete《硬化水泥浆、灰浆和混凝土长度变化测定用仪器使用的标准实施规程》.pdf》由会员分享，可在线阅读，更多相关《ASTM C490 C490M-2009 Standard Practice for Use of Apparatus for the Determination of Length Change of Hardened Cement Paste Mortar and Concrete《硬化水泥浆、灰浆和混凝土长度变化测定用仪器使用的标准实施规程》.pdf（5页珍藏版）》请在麦多课文档分享上搜索。

1、Designation: C490/C490M 09Standard Practice forUse of Apparatus for the Determination of Length Change ofHardened Cement Paste, Mortar, and Concrete1This standard is issued under the fixed designation C490/C490M; the number immediately following the designation indicates the yearof original adoption

2、 or, in the case of revision, the year of last 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 practice covers the requirements for the apparatusand equipment used t

3、o prepare specimens for the determinationof length change in hardened cement paste, mortar, andconcrete, the apparatus and equipment used for the determina-tion of these length changes, and the procedures for its use.1.2 Methods for the preparation and curing of test speci-mens, conditions of testin

4、g and curing, and detailed proceduresfor calculating and reporting test results are contained inapplicable test methods.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, each

5、system shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.2. Referenced Documents2.1 ASTM Standards:2C511 Specification for Mixing Rooms, Moist Cabinets,Moist Rooms, and Water Storage Tanks Used in theTesting of Hydraulic Cem

6、ents and ConcretesC1005 Specification for Reference Masses and Devices forDetermining Mass and Volume for Use in the PhysicalTesting of Hydraulic Cements3. Terminology3.1 length changean increase or decrease in the lineardimension of a test specimen, measured along the longitudinalaxis, due to cause

7、s other than applied load.4. Significance and Use4.1 This practice is intended to provide standard require-ments for apparatus common to many test methods used inconnection with cement and concrete and standardized proce-dures for its use. The detailed requirements as to materials,mixtures, specimen

8、s, conditioning of specimens, number ofspecimens, ages at which measurements are to be made,interpretation of results, and precision and bias are left to bedealt with in specific test methods.5. Apparatus5.1 Reference Masses and Devices for Determining Massand Volume, shall conform to the requiremen

9、ts of SpecificationC1005.5.2 Molds, shall have either one or two compartments andshall be constructed as shown in Fig. 1 or Fig. 2. Molds for testspecimens used in determining the length change of cementpastes and mortars shall provide for 25 by 25 by 285-mmprisms having a 250-mm gauge length, or fo

10、r 1 by 1 by 1114in. prisms having a 10in. gauge length. Molds for testspecimens used in the length change of concretes shall providefor prisms of the desired cross section having a 10-in. or250-mm gauge length. In some routine tests, 25 by 25 by160-mm specimens with a gauge length of 125 mm, or 1 by

11、 1by 614 in. specimens with a gauge length of 5-in. arepermitted, but in case of dispute, results obtained with speci-mens of 250-mm 10-in. gauge length shall govern.5.2.1 The gauge length shall be considered as the nominallength between the innermost ends of the gauge studs. Theparts of the molds s

12、hall be tight fitting and firmly held togetherwhen assembled, and their surfaces shall be smooth and free ofpits. The molds shall be made of steel or other hard metal notreadily attacked by the cement paste, mortar, or concrete. Thesides of the molds shall be sufficiently rigid to preventspreading o

13、r warping. For the molds shown in Fig. 1, thetolerance on dimension A is 60.7 mm. For the molds shown inFig. 2, the tolerance on dimension A is 60.03 in.5.2.2 Each end plate of the mold shall be equipped to holdproperly in place, during the setting period, one of the gaugestuds shown in Fig. 1 or Fi

14、g. 2. The gauge studs shall be ofAmerican Iron and Steel Institute (AISI)3Type 316 stainlesssteel or other corrosion-resistant metal of similar hardness.1This practice is under the jurisdiction ofASTM Committee C01 on Cement andis the direct responsibility of Subcommittee C01.95 on Coordination of S

15、tandards.Current edition approved Dec. 1, 2009. Published January 2010. Originallyapproved in 1962. Last previous edition approved in 2008 as C490 08. DOI:10.1520/C0490_C0490M-09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org.

16、 For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Details on this material are available from American Iron and Steel Institute(AISI), 1140 Connecticut Ave., NW, Suite 705, Washington, DC 20036, http:/www.steel.org.1*A Summary of C

17、hanges 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.Gauge studs of Invar or similar metal shall be used whenspecimens are tested at widely different temperatures. Toprevent restraint of t

18、he gauge studs before demolding of thespecimen, the device for holding the gauge studs in positionshall be so arranged that, if necessary, it can be partially orcompletely released after the compaction of the paste or mortarinto place in the mold. The gauge studs shall be set so that theirprincipal

19、axes coincide with the principal axis of the testspecimen. For the molds shown in Fig. 1, gauge studs shallextend into the specimen 17.5 6 0.5 mm and the distancebetween the inner ends of the gauge studs shall be 250.0 6 2.5mm and 250 mm shall be considered the gauge length forcalculating length cha

20、nge. For the molds shown in Fig. 2,gauge studs shall extend into the specimen 0.625 6 0.025 in.and the distance between the inner ends of the gauge studs shallbe 10.00 6 0.10 in. and 10 in. shall be considered the gaugelength for calculating length change.5.3 Length Comparator, for determining lengt

21、h change ofspecimens, shall be designed to accommodate the size ofspecimen employed and to provide or permit a positive meansof contact with the gauge studs and the convenient and rapidobtaining of comparator readings (Note 1).5.3.1 The comparator for determining length changes ofspecimens produced

22、in the molds shown in Fig. 1 shall providea dial micrometer or other measuring device graduated to readin 0.002-mm units or less, accurate within 0.002 mm in any0.020-mm range, and within 0.004 mm in any 0.200-mmrange, and sufficient range (at least 8.0 mm) in the measuringdevice to allow for small

23、variations in the actual length ofvarious specimens. The terminals of the comparator shall beplane, polished and heat-treated. They shall be fitted withcollars held in place with set screws. The collars shall extend1.5 6 0.1 mm beyond the plane face of the terminal. Thecollars shall allow free rotat

24、ion of the gauge stud tips that fitinside the collars and have an inside diameter no more than 0.5mm larger than the average diameter of that portion of thegauge stud tips that fit into the collars.NOTEDimension A to be specified by the purchaser.FIG. 1 Molds (SI Units)C490/C490M 092NOTE 1One type o

25、f instrument that has been found satisfactory foruse with small prisms is shown in Fig. 3. A horizontal comparator shouldbe used with prisms with a cross section greater than 9 in.2or 58 cm2.5.3.2 The comparator for determining length changes ofspecimens produced in the molds shown in Fig. 2 shall p

26、rovidea dial micrometer or other measuring device graduated to readin 0.0001-in. units, accurate within 0.0001 in. in any 0.0010-in.range, and within 0.0002 in. in any 0.0100-in. range, andsufficient range (at least 0.3 in.) in the measuring device toallow for small variations in the actual length o

27、f variousspecimens. The terminals of the comparator shall be plane,polished and heat-treated. They shall be fitted with collars heldin place with set screws. The collars shall extend 0.062 60.003 in. beyond the plane face of the terminal. The collarsshall allow free rotation of the gauge stud tips t

28、hat fit inside thecollars and have an inside diameter no more than 0.02 in. largerthan the average diameter of that portion of the gauge stud tipsthat fit into the collars.5.3.3 The design shall provide a means for checking themeasuring device against a reference bar at regular intervals.5.4 Referen

29、ce Bar, shall have an overall length of 295 6 3.0mm or 170 6 3.0 mm 1158 618 in. or 658 618 in.,whichever is appropriate for the specimen in use. The bar shallbe of a steel alloy having a coefficient of thermal expansion notgreater than two millionths per degree Celsius. Each end of thereference bar

30、 shall be fitted with heat treated, hardened, andpolished tips machined to the same shape as the contact end ofthe gauge studs used in test specimens. That portion of the barthat extends into the comparators collar shall have a diameterof 6 6 0.25 mm 0.250 6 0.010 in., and the length of thatportion

31、shall extend beyond the depth of the collar. Except forthe tips, which are attached after heat treatment, no part of thereference bar shall be heat treated. The central 100 mm 4 in.of the length of the reference bar shall be covered by a rubbertube with a wall at least 3 mm 18 in. thick to minimize

32、theeffect of temperature change during handling. The referencebar shall be provided near one end with a positioning mark.NOTE 2Alloys such as invar lose their low coefficient of thermalexpansion properties when heat treated.FIG. 2 Molds (Inch-Pound Units)C490/C490M 0935.5 Check and document the bar

33、mold dimensions, gaugestud projection into the mold interior, length comparator, andlength measuring device for conformance to the design anddimensional requirements of this specification at least every212 years.6. Procedure6.1 Preparation of MoldsPrior to the molding of speci-mens, the outside join

34、ts of the mold and the contact lines of themold and base plate shall be sealed to prevent loss of mixingwater from a freshly molded specimen. Thinly cover theinterior surfaces of the mold with mineral oil. After thisoperation, set the gauge studs, taking care to keep them clean,and free of oil, grea

35、se, and foreign matter.6.2 Use of Reference BarPlace the reference bar in theinstrument in the same position each time a comparator readingis taken. Check the dial gauge setting of the measuring deviceby use of the reference bar at least at the beginning and end ofthe readings made within a half day

36、 when the apparatus is keptin a room maintained at constant temperature. Check it moreoften when kept in a room where the temperature is notconstant.NOTE 3The equation given in the section on calculation of lengthchange contemplates that a comparator reading for the reference bar willbe recorded eac

37、h time the reference bar is used and a difference calculatedfor each test specimen reading. Alternatively, the dial gauge setting can bereset, if necessary, to its original setting with the reference bar in placeeach time the reference bar is read. Doing so simplifies the calculation oflength change

38、 by canceling the comparator reading of the reference barfrom the values of Lxand Li. If this procedure is used, care should be takento ensure that the dial set screw is tightened adequately each time the dialis reset.6.3 Obtaining Comparator ReadingsRotate specimensslowly in the measuring instrumen

39、t while the comparatorreading is being taken. Record the minimum reading of the dialif the rotation causes a change in the dial reading. Placespecimens in the instrument with the same end up each time acomparator reading is taken.6.3.1 Obtaining Comparator Readings of Specimens StoredMoistClean the

40、hole in the base of the comparator into whichthe gauge stud on the lower end of the bar fits (this hole tendsto collect water and sand and should be cleaned after everyreading). Read and record the comparator indication of thelength of the reference bar. Take one bar out of immersion, blotthe pins,

41、put the bar in the comparator, read, and record theindication. Return the bar to immersion and clean the hole inthe base of the comparator. Take out the second bar and treat itin a like manner. Return the second bar to immersion, recordthe reading, and clean the hole in the base of the comparator.Co

42、ntinue the procedure until all bars have been read, returnedto immersion, and the readings recorded, cleaning the hole inthe bottom of the comparator each time. After reading the lastbar, clean the hole in the comparator base and read and recordthe reference-bar indication. Blot only around the pins

43、 (Note4).NOTE 4The purpose of the minimal blotting of the pins and noblotting of the bars is to avoid drying and shrinkage of the bars. It has beenobserved that if the pins are blotted, and the bar placed in the comparatorand the dial read, and the bar is then wiped gently with a dry cloth, the barw

44、ill shrink measurably. Therefore, drying should be minimized.7. Calculation of Length Change7.1 Calculate the length change at any age as follows:L 5Lx2 Li!G3 100where:L = change in length at x age, %,Lx= comparator reading of specimen at x age minuscomparator reading of reference bar at x age; inmi

45、llimetres when using Fig. 1 apparatus, in incheswhen using Fig. 2 apparatus,Li= initial comparator reading of specimen minus com-parator reading of reference bar at that same time; inmillimetres when using Fig. 1 apparatus, in incheswhen using Fig. 2 apparatus, andG = nominal gauge length, 250 mm wh

46、en using Fig. 1apparatus, 10 in. when using Fig. 2 apparatus.7.2 Calculate length change values for each specimen to thenearest 0.001 % and report averages to the nearest 0.01 %.8. Temperature, Humidity, and Time8.1 Molding RoomThe temperature of the molding roomand dry materials shall be maintained

47、 between 23.0 6 4 C.The relative humidity shall be not less than 50 %. Thetemperature of the mixing water shall be 23.0 6 2.0 C.FIG. 3 Type of Suitable Apparatus for Measurement of LengthChangesC490/C490M 0948.2 Moist Storage FacilityThe temperature and humidityof the air in the moist storage facili

48、ty shall conform to therequirements of Specification C511.8.3 TimeComparator readings shall be taken at specifiedtime intervals or ages. All intervals and ages shall be metwithin 62%.9. Keywords9.1 cement paste; comparator; concrete; length change ap-paratus; molds; mortarSUMMARY OF CHANGESCommittee

49、 C01 has identified the location of selected changes to this practice since the last issue, C490 08,that may impact the use of this practice. (Approved December 1, 2009)(1) Moved part of 5.3.3 into new 5.4 and renumbered subse-quent paragraphs.Committee C01 has identified the location of selected changes to this practice since the last issue, C490 07,that may impact the use of this practice. (Approved June 1, 2008)(1) Editorially changed the designation to dual editorially toagree with the units statement in the Scope.(2) Revised 5.3.1