1、Designation: C1148 92a (Reapproved 2014)Standard Test Method forMeasuring the Drying Shrinkage of Masonry Mortar1This standard is issued under the fixed designation C1148; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、 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 is
3、applicable to Specification C270Type 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 resear
4、ch 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 con
5、cerns, 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:2C109/C109M Test Method for Compressive
6、 Strength ofHydraulic Cement Mortars (Using 2-in. or 50-mm CubeSpecimens)C157/C157M Test Method for Length Change of HardenedHydraulic-Cement Mortar and ConcreteC270 Specification for Mortar for Unit MasonryC305 Practice for Mechanical Mixing of Hydraulic CementPastes and Mortars of Plastic Consiste
7、ncyC490 Practice for Use of Apparatus for the Determination ofLength 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 ConcretesC778 Specification for Sand3. Signifi
8、cance 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 initial period of moi
9、st 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 include restraint, mason
10、ry unitabsorption, ambient temperature and humidity, thickness ofjoint, length of continuous wall, etc.4. Apparatus4.1 Scales and Weights, Glass Graduates, and LengthComparator, conforming to requirements of SpecificationC490.4.2 Molds (for test specimens), providing for 25 by 25 by285-mm (1 by 1 by
11、 11.25-in.) prisms having an effective gagelength of 250 mm (10 in.), and conforming to the requirementsof Specification C490.4.3 Studs, conforming to the requirements of SpecificationC490.4.4 Tamper and Demolding Apparatus, conforming to re-quirements of Test Method C157/C157M.4.5 Trowel, having a
12、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 ofSpecification C490.1This test method
13、is under the jurisdiction of ASTM Committee C12 on Mortarsand Grouts for Unit Masonry and is the direct responsibility of SubcommitteeC12.02 on Research and Methods of Test.Current edition approved Dec. 15, 2014. Published December 2014. Originallyapproved in 1990. Last previous edition approved in
14、2008 as C1148 92a (2008).DOI: 10.1520/C1148-92AR14.2For 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 ASTM website.Copyright
15、ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 Moist Storage FacilityThe temperature and humidityof the air in the moist storage facility shall conform to therequirements of Specification C511.5.3 Drying Room and ControlsThe drying room an
16、dcontrols shall conform to the requirements of Test MethodC157/C157M.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
17、 specimens 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 SpecificationC270 for the determination of the compressive strengt
18、h ofmortar.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 SpecificationC778.6.3 Mixing Mortar:6.3.1 Mix the mortar according to the requirements ofPractice C305.6.3.2 Mix the morta
19、r to a flow of 110 6 5, as determined bythe applicable sections of Test Method C109/C109M.6.3.3 Molding of SpecimensMold the specimens in con-formance with the requirements of Test Method C157/C157M.6.4 Curing and Storage of Test Specimens:6.4.1 Cure, store, and measure the test specimens in confor-
20、mance with the requirements of Test Method C157/C157Mexcept:6.4.1.1 Moist cure the specimens in the molds for 48 612h.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
21、in conformance with require-ments of Specification C490.8. 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 C490.NOTE 1The initial m
22、easurement of 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 C157/C157M with
23、a clearance of atleast 25 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
24、ofdays of drying in 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# 3100 (1)where:L0= effective gage lengt
25、h, cm (in.),L1= initial 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 Dat
26、e and number of specimens 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 indiv
27、idual and mean values 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.
28、1 drying shrinkage; masonry; mortar; unrestrainedC1148 92a (2014)2ASTM 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 s
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