1、Designation: C 1148 92a (Reapproved 2002)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 (e) 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
3、is 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 re
4、search purposes only.1.4 The values stated in SI units are to be regarded as thestandard. The values in parentheses are provided for informa-tion only.1.5 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
5、 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:C 109 Test Method for Compressive Strength of HydraulicCement Mortars (Using 2-in. or 50-mm Cube Specimens)2C 157 Test Met
6、hod for Length Change of Hardened Hy-draulic Cement Mortar and Concrete3C 270 Specification for Mortar for Unit Masonry4C 305 Practice for Mechanical Mixing of Hydraulic CementPastes and Mortar of Plastic Consistency2C 490 Practice for Use of Apparatus for the Determinationof Length Change of Harden
7、ed Cement Paste, Mortar, andConcrete2C 511 Specification for Moist Cabinets, Moist Rooms, andWater Storage Tanks Used in the Testing of HydraulicCements and Concretes2C 778 Specification for Standard Sand23. Significance and Use3.1 The drying shrinkage of mortar as determined by thistest method is a
8、 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 moist curing, measurements ofdrying shrinkage by this test method are most useful forcom
9、parative 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, masonry unit absorp-tion, ambient temperature and humidity, thickness of joint,length of c
10、ontinuous 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 25 by 25 by285-mm (1 by 1 by 11.25-in.) prisms having an effective gagelength of 250 mm (10 in.), and confo
11、rming 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 157.4.5 Trowel, having a straight edged steel blade 100 to 150mm (4 to 6 in.) in length.5. Temperature and
12、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 C 490.5.2 Moist Storage FacilityThe temperature and humidityof the air in the moist storage facility shal
13、l conform to therequirements of Specification C 511.5.3 Drying Room and ControlsThe drying room andcontrols shall conform to the requirements of Test MethodC 157.1This test method is under the jurisdiction of ASTM Committee C12 on Mortarsfor Unit Masonry and is the direct responsibility of Subcommit
14、tee C12.02 onResearch and Methods of Test.Current edition approved May 21, 1992. Published July 1992. Originallypublished as C 1148 90. Last previous edition C 1148 92.2Annual Book of ASTM Standards, Vol 04.01.3Annual Book of ASTM Standards, Vol 04.02.4Annual Book of ASTM Standards, Vol 04.05.1Copyr
15、ight ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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 prefe
16、rable that 15 specimens be made withfive 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 SpecificationC 270 for the
17、 determination of the compressive strength 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 SpecificationC 778.6.3 Mixing Mortar:6.3.1 Mix the mortar according to the requir
18、ements ofPractice C 305.6.3.2 Mix the mortar 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 meas
19、ure the test specimens in con-formance with the 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 612h from thetime of molding.7. Preparation of Apparatu
20、s7.1 Prepare specimen molds in conformance with 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 Specifica
21、tion C 490.NOTE 1The initial measurement 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 o
22、f Test Method C 157 with a clearance of at least25 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
23、 at the specified number 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# 3 100 (1)wher
24、e:L0= effective gage length, 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 spe
25、cimen materials,10.1.2 Date 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
26、taken, and10.1.6 The individual 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
27、 this time.12. Keywords12.1 drying shrinkage; 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
28、 of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments
29、 are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not
30、received a fair hearing you shouldmake your 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 (2002)2
