1、Designation: C 157/C 157M 08Standard Test Method forLength Change of Hardened Hydraulic-Cement Mortar andConcrete1This standard is issued under the fixed designation C 157/C 157M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the
2、 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.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This test method covers the
3、 determination of the lengthchanges that are produced by causes other than externallyapplied forces and temperature changes in hardened hydraulic-cement mortar and concrete specimens made in the laboratoryand exposed to controlled conditions of temperature andmoisture.1.2 The values stated in either
4、 SI units or inch-pound unitsare to be regarded separately as standard. An exception is withregard to sieve sizes and nominal size of aggregate, in whichthe SI values are the standard as stated in Specification E11.Within the text, the SI units are shown in brackets. The valuesstated in each system
5、may not be exact equivalents; therefore,each system shall be used independently of the other. Combin-ing values from the two systems may result in non-conformance with the standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresp
6、onsibility 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. Referenced Documents2.1 ASTM Standards:2C 125 Terminology Relating to Concrete and ConcreteAggregatesC 143/C 143M Test Method for S
7、lump of Hydraulic-Cement ConcreteC 172 Practice for Sampling Freshly Mixed ConcreteC 192/C 192M Practice for Making and Curing ConcreteTest Specimens in the LaboratoryC 305 Practice for Mechanical Mixing of Hydraulic CementPastes and Mortars of Plastic ConsistencyC 490 Practice for Use of Apparatus
8、for the Determinationof Length Change of Hardened Cement Paste, Mortar, andConcreteC511 Specification for Mixing Rooms, Moist Cabinets,Moist Rooms, and Water Storage Tanks Used in theTesting of Hydraulic Cements and ConcretesC 596 Test Method for Drying Shrinkage of Mortar Con-taining Hydraulic Ceme
9、ntC 1347 Practice for Preparation and Dissolution of UraniumMaterials for AnalysisE11 Specification for Wire Cloth and Sieves for TestingPurposesE 337 Test Method for Measuring Humidity with a Psy-chrometer (the Measurement of Wet- and Dry-Bulb Tem-peratures)3. Terminology3.1 DefinitionsThe terms us
10、ed in this test method aredefined in Terminology C 125.3.2 Definitions of Terms Specific to This Standard:3.2.1 length change, nan increase or decrease in thelength of a test specimen that has been caused to change by anyfactor other than externally applied forces and temperaturechanges.4. Significa
11、nce and Use4.1 Measurement of length change permits assessment ofthe potential for volumetric expansion or contraction of mortaror concrete due to various causes other than applied force ortemperature change. This test method is particularly useful forcomparative evaluation of this potential in diff
12、erent hydraulic-cement mortar or concrete mixtures.4.2 This test method provides useful information for experi-mental purposes or for products that require testing undernonstandard mixing, placing, handling, or curing conditions,such as high product workability or different demolding times.Standard
13、conditions are described in 5.4.1.4.3 If conditions for mixing, curing, sampling, and storageother than specified in this test method are required, they shallbe reported but are not to be considered as standard conditions1This test method is under the jurisdiction of ASTM Committee C09 onConcrete an
14、d Concrete Aggregates and is the direct responsibility of SubcommitteeC09.68 on Volume Change.Current edition approved Oct. 1, 2008. Published November 2008. Originallyapproved in 1940. Last previous edition approved in 2006 as C 157/C 157M 06.2For referenced ASTM standards, visit the ASTM website,
15、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 ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Driv
16、e, PO Box C700, West Conshohocken, PA 19428-2959, United States.of this test method. Nonstandard conditions and the reasons fordeparture from standard conditions shall be reported clearlyand prominently with comparator values.5. Apparatus5.1 Molds and Length ComparatorThe molds for castingtest speci
17、mens and the length comparator for measuring lengthchange shall conform to the requirements of Practice C 490.5.2 TamperThe tamper shall be made of a nonabsorptive,nonabrasive material such as medium-hard rubber or seasonedoak wood rendered nonabsorptive by immersion for 15 min inparaffin at approxi
18、mately 392 F 200 C, and shall have across section of12 by 1.0 in. 13 by 25 mm and a convenientlength of about 6 in. 150 mm. The tamping face of the tampershall be flat and at right angles to the length of the tamper.5.3 Tamping RodThe tamping rod shall be a straight steelrod38 in. 10 mm in diameter
19、and not less than 10 in. 250mm in length, having at least the tamping end rounded to ahemispherical tip of the same diameter.5.4 Drying Room and ControlsA drying room with suit-able racks shall be provided when storing specimens in air. Theracks shall be designed for free circulation of air aroundsp
20、ecimens, except for necessary supports, and shall be sosituated with respect to the nearest wall or other obstructionthat air circulation is not restricted in the intervening space.The supports shall be horizontal and shall consist of twononabsorptive members not deeper than 1 in. 25 mm andhaving a
21、bearing area of not more than14 in. 6 mm in width.Conditioned air shall be circulated into and out of the room ina uniform manner so that the specified rate of evaporation isattained adjacent to all specimens.5.4.1 The air in the room shall be maintained at a tempera-ture of 73 6 3F236 2 C and a rel
22、ative humidity of 50 64 %. The air movement past all specimens shall be such thatthe rate of evaporation is 77 6 30-mL/24 h from an atmometeror 13 6 5-mL/24 h from a 400-mL Griffin low-form beakerfilled to34 in. 20 mm from the top. The temperature andrelative humidity of the air in the room shall be
23、 measured witheither a sling or Assmann psychrometer at least twice eachworking day. The psychrometer shall comply with Test MethodE 337, except that thermometers having an overall length of 10in. 250 mm and marked in subdivisions of 0.5 F 0.25 Care permitted. The room shall be equipped with a means
24、 ofmeasuring and recording wet- and dry-bulb temperaturescontinuously. Correction factors as indicated by the sling orAssmann psychrometer shall be applied to the recorded data.The rate of evaporation within the room shall be determineddaily by the use of the atmometer or by the loss of mass ofwater
25、 from a 400-mL Griffin low-form beaker filled initially to34 in. 20 mm from the top.5.5 AtmometerThe atmometer shall be constructed asshown in Fig. 1.5.5.1 MountingFig. 2 shows a suggested arrangement foroperating the atmometer. Punch a central hole12 in. 13 mmin diameter in a filter paper, place it
26、 on the atmometer, andsecure it in place while dry, by turning the torque handle only,until it just starts to slip. Mount the atmometer on a stand withthe filter paper in a horizontal position. Mount a 100-mL glassgraduate so that the 100-mL mark is from 1 to 3 in. 25 to 75mm below the level of the
27、filter paper. Stopper the graduate sothat entrance is provided for two short glass tubes not extend-ing to the water level and one long tube extending to thebottom of the graduate. Connect the glass tubing leading fromthe bottom of the graduate to the inlet of the atmometer bymeans of clear plastic
28、tubing.5.5.2 OperationUse clear plastic tubing to connect asqueeze bottle containing distilled or deionized water to one ofthe short glass tubes into the graduate. Force water into thegraduate until it is about half full and then close the remainingglass tube into the graduate. Continue to force wat
29、er throughthe graduate into the atmometer until the filter paper issaturated and there are no air bubbles in the system. Open theglass tube into the graduate and release pressure on the squeezebottle gradually to avoid trapping air in the tube leading to theatmometer. Adjust the level of water in th
30、e graduate toapproximately the 100-mL mark. If the atmometer is to be usedunder variable temperature conditions, disconnect the squeezebottle after filling the graduate to avoid the possibility ofadditional water being forced into the graduate. Permit evapo-ration of water from the filter paper for
31、1 h before recording thetime and initial reading of the graduate. It is not permitted toomit the waiting period during subsequent use of the atmom-eter provided the filter paper does not become dry. Change thefilter paper whenever it shows signs of contamination but notless frequently than once ever
32、y two weeks.5.6 Filter PaperThe filter paper to be used with theatmometer shall be white with a smooth surface texture. It shallbe 6 in. 152 mm in diameter and 0.050 6 0.003 in. 1.27 60.08 mm thick and shall have a cotton fiber content of not lessthan 75 weight %. The density shall be between 0.400
33、and0.425 g/cm3. The Mullen bursting strength shall not be lessthan 50 psi 345 kPa.NOTE 1E and D filter paper No. 6253has been found suitable.5.7 Apparatus for Demolding SpecimensIt is useful toconstruct an apparatus for demolding specimens molded indouble molds as detailed in Fig. 3 or to a differen
34、t design thatserves the same purpose. When this device is to be used, thecenter side plate of the double mold must be appropriatelydrilled and tapped to receive the 8-32 by58 in. 4.5-0.74 IMCby 16 mm machine screw of the demolding thumbscrew. Fig.4 shows the details of a suitable apparatus for demol
35、dingspecimens molded in single molds.3The sole source of supply of the apparatus known to the committee at this timeis Ahlstrom Filtration Co., Mt. Holly Springs, PA 17065. If you are aware ofalternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will
36、 receive careful consideration at a meeting of theresponsible technical committee,1which you may attend.C 157/C 157M 082FIG. 1 AtmometerC 157/C 157M 083ASTM C 157 FIGURESFigure Di-mensionsSI Units Inch-Pound UnitsA Adjustable torque handle Adjustable torque handle1.41.7 Nm 1215 in.lbB Jam nut Jam nu
37、t1015 IMC38-in.16 NCC 10-mm diameter 1.5 IMC Thd.38-in. dia16 NC Thd.D 12-mm diameter 1.5 IMC Thd.12-in. dia20 NC Thd.E 64-mm diameter 2.50-in. diameterF 64-mm diameter 2.50-in. diameterG 57-mm diameter 2.25-in. diameterH 52-mm diameter 2.06-in. diameterI 51-mm diameter 2.00-in. diameterJ 14mm 0.56i
38、n.K 8 mm 0.31 in.L 13mm 0.50in.M 3 mm 0.125 in.N 8 mm 0.31 in.O 19mm 0.75in.P 32mm 1.25in.Q 53mm 2.06in.R 1.5-mm drill through 11.5-mm Cdrill116-in. drill through2964-in. C drill32-mm deep tap 12-mm 1.5-mmIMF Thd114-in. deep tap12-in.20 ThdS 19 mm deep 16 mm C bore 6mm deep34-in. deep58-in. C bore14
39、 in.deepT 5-mm drill 3-mm deep C drill316-in. drill18-in. deep C drillat 60 as shown at 60 as shownthrough to center tapped hole through to center tapped holeU 3 mm 0.12 in. diameterV 2 mm 0.09 in.W 10mm 0.40in.X 60mm 2.36in.Y 35mm 1.37in.Z 6 mm 0.25 in.AA 6mm 0.25in.BB 4mm 0.15in.CC 6mm 0.25in.DD 2
40、3 mm 0.87 in.EE 38 mm 1.50 in.FF 25 to 75 mm 1 to 3 in.GG 35 mm high 1.37 in. highHH 100 mm 4 in.II 130 mm 5 in.JJ 8 cm6.1 kg/m channel 3 in.4.1 lb/ft channelKK 20 mm34 in.LL 330 mm 13 in.MM 142.0 IMC Thd.12 in.12 Thd.NN 20 mm34 in.OO 50 mm 2 in.PP 20 mm34 in.QQ 60 mm14 in.RR 10 mm38 in.SS Drill Cl.
41、 hole for Drill Cl. hole for4.50.75 IMC machine screw 832 in. machine screwTT 13 mm12 in.UU 25 mm 1 in.VV 30 mm 1-316 in.WW 60 mm 2-38 in.XX 12.5 mm12 in.YY 6-mm diameter steel rod14-in. diameter steel rodZZ 4.50.75 IMC 3 16-mm machinescrew832 358-in. machine screw6. Sampling6.1 Take samples accordi
42、ng to the applicable provisions ofPractice C 192/C 192M from batches of hydraulic-cementmortar or concrete made in the laboratory (Note 2).NOTE 2When collecting samples in nonstandard conditions, such asfield concrete, it is suggested that Practice C 172 be followed. Field castspecimens can show up
43、to twice as much drying shrinkage as laboratorycast specimens from the same materials and proportions.FIG. 2 Atmometer AssemblyInstructions for UseRemove the end and the outer side plates leaving thebase, center side plate, and gage stud holders in place. Engage the machinescrew in the drilled and t
44、apped end of the center side plate. Turn the thumbscrewto loosen the bars.FIG. 3 Device for Detaching 1-in. 25-mm Square by 1114-in.285-mm Bars from Center Side Plate of Double MoldsNOTEDimensions shown are appropriate for one design of mold for3-in. 75-mm square specimens. Change dimensions as requ
45、ired for othermolds.FIG. 4 Device for Demolding Specimens from Single MoldsC 157/C 157M 0847. Test Specimens7.1 MortarThe test specimen for mortar shall be a prismof 1-in. 25-mm square cross-section and approximately 1114in. 285 mm in length. Three specimens shall be prepared foreach test condition.
46、7.2 ConcreteThe test specimen for concrete, in which allof the aggregate passes a 2-in. 50-mm sieve, shall be a prismof 4-in. 100-mm square cross-section and approximately 1114in. 285 mm long. However, a prism of 3-in. 75-mm squarecross-section shall be used if all of the aggregate passes a 1-in.sie
47、ve 25.0-mm. Three specimens shall be prepared for eachtest condition. Since length change is capable of being influ-enced by the size of the specimen, specimens to be comparedshall have the same dimensions, and any specification limitbased upon this method shall be applied to a specified size ofspec
48、imen.8. Procedure for Mixing Mortars and Concrete8.1 If the mortar or concrete to be tested is made inaccordance with requirements other than those given in one ofthe following paragraphs, samples shall be taken and speci-mens molded as described in the sections on sampling and onmolding specimens.8
49、.2 Bring all materials to a temperature between 65 and 75F 18 and 24 C before using to make mortar or concrete.Proportion solid materials by mass (that is, not by volume). Itis permissible to batch water and liquid admixtures either bymass or by volume. For calculation of batch quantities, assumeaggregates to be saturated and surface-dry; if they are not inthis condition at the time of use, apply appropriate corrections,as necessary, to batc
