1、Designation: C 1148 92a (Reapproved 2008)Standard Test Method forMeasuring the Drying Shrinkage of Masonry Mortar1This standard is issued under the fixed designation C 1148; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the measurement of unre-strained drying shrinkage of masonry mortars.1.2 This test method i
3、s applicable to Specification C 270Type N, Type S, and Type M mortars under the property orproportion specifications. Due to the tendency to damage lowerstrength specimens during demolding, it is not applicable tolower strength mortars, such as Type O mortars.1.3 This test method is intended for res
4、earch purposes only.1.4 The values stated in SI units are to be regarded asstandard. The values given in parentheses are mathematicalconversions to inch-pound units that are provided for informa-tion only and are not considered standard.1.5 This standard does not purport to address all of thesafety
5、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. Referenced Documents2.1 ASTM Standards:2C 109/C 109M Test Method for Compre
6、ssive Strength ofHydraulic Cement Mortars (Using 2-in. or 50-mm CubeSpecimens)C 157/C 157M Test Method for Length Change of Hard-ened Hydraulic-Cement Mortar and ConcreteC 270 Specification for Mortar for Unit MasonryC 305 Practice for Mechanical Mixing of Hydraulic CementPastes and Mortars of Plast
7、ic ConsistencyC 490 Practice for Use of Apparatus 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 778 Specification for S
8、tandard Sand3. Significance and Use3.1 The drying shrinkage of mortar as determined by thistest method is a measure of the decrease in length of testspecimens under controlled drying conditions, after an initialperiod of moist curing.3.2 Since test specimens are not completely unrestrainedduring the
9、 initial period of moist curing, measurements ofdrying shrinkage by this test method are most useful forcomparative purposes rather than as absolute values.3.3 The drying shrinkage of unrestrained laboratory testedmortar samples is different from that experienced in a masonrywall where influences in
10、clude restraint, masonry unit absorp-tion, ambient temperature and humidity, thickness of joint,length of continuous wall, etc.4. Apparatus4.1 Scales and Weights, Glass Graduates, and Length Com-parator, conforming to requirements of Specification C 490.4.2 Molds (for test specimens), providing for
11、25 by 25 by285-mm (1 by 1 by 11.25-in.) prisms having an effective gagelength of 250 mm (10 in.), and conforming to the requirementsof Specification C 490.4.3 Studs, conforming to the requirements of SpecificationC 490.4.4 Tamper and Demolding Apparatus, conforming to re-quirements of Test Method C
12、157.4.5 Trowel, having a straight edged steel blade 100 to 150mm (4 to 6 in.) in length.5. Temperature and Humidity5.1 Molding RoomThe temperature of the molding room,dry materials, mixing water, and the relative humidity of the airin the molding room shall conform to the requirements ofSpecificatio
13、n C 490.5.2 Moist Storage FacilityThe temperature and humidityof the air in the moist storage facility shall conform to therequirements of Specification C511.1This test method is under the jurisdiction of ASTM Committee C12 on Mortarsand Grouts for Unit Masonry and is the direct responsibility of Su
14、bcommitteeC12.02 on Research and Methods of Test.Current edition approved Nov. 1, 2008. Published November 2008. Originallyapproved in 1990. Last previous edition approved in 2002 as C 1148 92a(2002).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Servic
15、e at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.3 Drying Room and ControlsThe drying room an
16、dcontrols shall conform to the requirements of Test MethodC 157.6. Test Specimens6.1 Number of Test Specimens:6.1.1 Make five test specimens. Although the number of testspecimens may consist of five specimens made from a singlebatch of mortar, it is preferable that 15 specimens be made withfive spec
17、imens being made from each of three batches, witheach batch being made on a different day.6.2 Preparation of Test Specimens:6.2.1 Proportioning Mortar MaterialsMeasure materialsfor testing according to the procedures outlined in SpecificationC 270 for the determination of the compressive strength of
18、mortar.6.2.2 To test the behavior of cementitious components of amortar independent of the qualities of the masonry sand, usestandard graded sand meeting the requirements of SpecificationC 778.6.3 Mixing Mortar:6.3.1 Mix the mortar according to the requirements ofPractice C 305.6.3.2 Mix the mortar
19、to a flow of 110 6 5, as determined bythe applicable sections of Test Method C 109.6.3.3 Molding of SpecimensMold the specimens in con-formance with the requirements of Test Method C 157.6.4 Curing and Storage of Test Specimens:6.4.1 Cure, store, and measure the test specimens in con-formance with t
20、he requirements of Test Method C 157 except:6.4.1.1 Moist cure the specimens in the molds for 48612 h.6.4.1.2 After 48 612 h remove the specimens from themolds and moist cure until specimen age is 72 612 h from thetime of molding.7. Preparation of Apparatus7.1 Prepare specimen molds in conformance w
21、ith require-ments of Specification C 490.8. Procedure8.1 MeasurementRemove the specimens from the moiststorage at the age of 72 612 h, wipe with a damp cloth, andimmediately measure their length with a length comparatormeeting the requirements of Specification C 490.NOTE 1The initial measurement of
22、specimen length may be takeneither immediately after demolding or at alternative initial moist curingages when the effect of that variable on drying shrinkage is the subject ofinvestigation.8.1.1 Place specimens in drying room conforming to re-quirements of Test Method C 157 with a clearance of at l
23、east25 mm (1 in.) on all sides.8.1.2 Measure the length of the specimens after 4, 11, 18and 25 days of air storage unless otherwise specified.NOTE 2Drying shrinkage may not stabilize in the 25-day time periodof air storage. Plotting results of measurements at the specified number ofdays of drying in
24、 air storage may be used to determine if additionalmeasurements at extended drying ages are desirable or to estimateultimate drying shrinkage.9. Calculation9.1 Calculate the percent shrinkage, S, of the five specimensas follows:S 5 L12 L!/L0# 3 100 (1)where:L0= effective gage length, cm (in.),L1= in
25、itial measurement after removal from moist cure,cm, (in.), andL = measurement during or after drying, cm (in.)9.2 Calculate the mean of the drying shrinkage of the fivebars.10. Report10.1 Report the following information:10.1.1 Identification of mortar specimen materials,10.1.2 Date and number of sp
26、ecimens molded,10.1.3 Proportions and flow of mortar,10.1.4 Total elapsed number of days drying in air storage,10.1.5 Percent shrinkage as determined for each specimenand the number of days of drying in air storage at whichmeasurement of length change was taken, and10.1.6 The individual and mean val
27、ues of the drying shrink-age of the five specimens at each age measured.10.1.7 Note any changes from curing and drying proceduresspecified by this test method.11. Precision and Bias11.1 Data necessary to determine the precision and bias arenot available at this time.12. Keywords12.1 drying shrinkage
28、; masonry; mortar; unrestrainedASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof i
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31、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.org (e-mail); or through the ASTM website(www.astm.org).C 1148 92a (2008)2
