1、Designation: C1792 14Standard Test Method forMeasurement of Mass Loss versus Time for One-Dimensional Drying of Saturated Concretes1This standard is issued under the fixed designation C1792; the number immediately following the designation indicates the year oforiginal adoption or, in the case of re
2、vision, the year 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 determines the mass loss over time dueto one-dimensional drying and moisture tran
3、sport in an initiallysaturated cylindrical specimen with both ends exposed toconstant temperature and relative humidity.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of the
4、safety 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:2C31/C31M Practice for Making
5、 and Curing Concrete TestSpecimens in the FieldC42/C42M Test Method for Obtaining and Testing DrilledCores and Sawed Beams of ConcreteC125 Terminology Relating to Concrete and Concrete Ag-gregatesC157/C157M Test Method for Length Change of HardenedHydraulic-Cement Mortar and ConcreteC192/C192M Pract
6、ice for Making and Curing Concrete TestSpecimens in the LaboratoryC511 Specification for Mixing Rooms, Moist Cabinets,Moist Rooms, and Water Storage Tanks Used in theTesting of Hydraulic Cements and ConcretesC670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction M
7、aterialsC1005 Specification for Reference Masses and Devices forDetermining Mass and Volume for Use in the PhysicalTesting of Hydraulic CementsE104 Practice for Maintaining Constant Relative Humidityby Means of Aqueous Solutions3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in thi
8、s standard, refer toTerminology C125.4. Summary of Test Method4.1 Saturated cylindrical concrete specimens with sealedsides are prepared and the two ends are exposed to anenvironment at 23C and 50 % relative humidity (RH),subjecting the specimen to one-dimensional drying. Theirmasses are measured pe
9、riodically to establish a data set ofaverage mass loss versus time.5. Significance and Use5.1 Drying behavior is related to the mass transport proper-ties of concrete, such as liquid permeability and water diffu-sivity. It depends on a number of factors such as concretemixture proportions, presence
10、of admixtures and supplemen-tary cementitious materials, composition and physical charac-teristics of the aggregates and cementitious materials, curingconditions, degree of hydration, and presence of microcrack-ing. Drying behavior is also affected strongly by the degree ofsaturation and temperature
11、 of the concrete at the start of dryingas well as the environmental conditions that exist during dryingsuch as temperature, relative humidity, and air flow rate (windspeed).5.2 This test method subjects initially saturated specimensof concrete to one-dimensional drying under controlled envi-ronmenta
12、l conditions. The resulting mass loss versus time datacan be used to estimate transport coefficients including liquidpermeability3and water diffusivity.4These coefficients may be1This test method is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct res
13、ponsibility of SubcommitteeC09.66 on Concretes Resistance to Fluid Penetration.Current edition approved July 1, 2014. Published July 2014. DOI: 10.1520/C1792-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book o
14、f ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Baroghel-Bouny, V., Thiery, M., Barberon, F., Coussy, O., and Villain, G.,“Assessment of Transport Properties of Cementitious Materials: A Major Challengeas Regards Durability?,” European Reviews in
15、Civil Engineering, Vol 11, No. 6,2007, pp. 671696.4Samson, E., Maleki, K., Marchand, J., and Zhang, T., “Determination of theWater Diffusivity of Concrete Using Drying/Absorption Test Results,” Journal ofASTM International, Vol 5, No. 7, 2008, pp. 112.Copyright ASTM International, 100 Barr Harbor Dr
16、ive, PO Box C700, West Conshohocken, PA 19428-2959. United States1used in numerical models to estimate service life of concreteand reinforced concrete members exposed to different environ-mental conditions.5,65.3 The test method provides instruction and a sequence ofsteps for measuring mass loss ver
17、sus time.The preferred rate ofthis mass loss will depend on the application. For example, forinterior commercial flooring applications, a mass loss thatoccurs quickly may be preferable, while for outdoor exposuresin an aggressive environment, slower mass loss may bebeneficial.6. Apparatus6.1 Drying
18、Chamber, a temperature- and humidity-controlled chamber or room with temperature maintainedconstant at 23C 6 2C and relative humidity at 50 % 6 4%,such as the drying room specified in Test Method C157/C157M. The chamber shall have proper specimen supports toallow airflow around each concrete specime
19、n (see Note 1). Thechamber shall be of sufficient volume to hold at least three testspecimens (see Note 2). The air movement around the speci-mens within the chamber shall result in an evaporation rate asrequired for the drying room described in Test Method C157/C157M.NOTE 1Rack shelving composed of
20、 metal, plastic, or compositematerials will provide a convenient pathway for air circulation aroundeach supported specimen.NOTE 2A walk-in chamber is preferable, so that the balance can beinstalled and maintained at constant conditions.6.2 Temperature and Relative Humidity MeasuringEquipment, of the
21、 digital type to be placed next to thespecimens in the drying chamber and capable of measuringrelative humidity with an accuracy of 63 % at a relativehumidity of 50 % and temperature with an accuracy of 60.5 Cat a temperature of 23C. At least two separate measurementsof both temperature and relative
22、 humidity are required for eachdrying chamber. Measurements shall be obtained at intervals of15 min or less.NOTE 3The accuracy of the relative humidity measured by theequipment can be verified by measurement of relative humidity overaqueous solutions of various salts, as outlined in Practice E104.6.
23、3 Absorbent Towels, wetted thoroughly and wrung out, forblotting free water from specimen surfaces.6.4 Balance, complying with Specification C1005 with acapacity of at least 1500 g, but with an index scale readable toat least 0.01 g.6.5 Water-Cooled Saw, with diamond impregnated blade ofadequate dim
24、ensions to cut test specimens from larger samples.6.6 Caliper, to measure the specimen dimensions to thenearest 0.1 mm.6.7 Compressed Air, source of compressed air at sufficientpressure to dry surfaces of specimens.7. Materials7.1 Sealing Material, strips of low permeability adhesivesheets, epoxy co
25、ating, or (paraffin) wax for sealing the sidesurfaces of test specimens. The hardening time of the sealingmaterial shall not exceed 30 minutes. The adequacy of thesealing material is to be verified with respect to both drying andlimewater immersion.Adequacy with respect to drying is to beverified by
26、 sealing a saturated specimen on all sides and storingit in the drying chamber for 3 days. The sealing material isadequate if the measured mass loss is less than 0.1 % of theoriginal mass of the sealed specimen. The sealing material alsomust not gain mass or deteriorate when placed in a limewatersol
27、ution. Adequacy with respect to limewater immersion is tobe verified by sealing a saturated specimen on all sides andimmersing it in limewater for 7 days. Visually examine thesealing material after immersion to detect any reaction with thelimewater. The sealing material is adequate if the measuredma
28、ss gain is less than 0.1 % of the original mass of the sealedspecimen.8. Sampling, Test Specimens, and Test Units8.1 Three cylindrical sawcut specimens are to be preparedfor each concrete mixture to be evaluated. Unless requiredotherwise by the specifier of the tests, specimen dimensionsafter cuttin
29、g shall be a diameter of 100 mm 6 5 mm and alength of 50 mm 6 2 mm. Specimens are cut to length, usinga water-cooled saw (see 6.5), from either cylinders moldedaccording to Practices C31/C31M or C192/C192M or coresdrilled according to Test Method C42/C42M. The averagediameters (see 9.3) of the end f
30、aces of a specimen shall notdiffer by more than 1 mm.NOTE 4While other specimen sizes may be employed, the minimumspecimen dimension should exceed the nominal maximum aggregate sizeby a factor of two or more. Because the drying is one-dimensional throughthe exposed cylinder faces, a nominal diameter
31、-length ratio of 2.0 does nothave to be used if alternative specimen sizes are specified.8.2 This test method may be applied to either specimenscontaining a cast or a finished wearing surface or those inwhich the cast or finished surface layer(s) of the concrete havebeen removed by sawing. In the la
32、tter case, the distancesbetween the original exposed surface of the concrete and theend faces of replicate test specimens shall be within 5 mm ofeach other.NOTE 5An exterior surface of a concrete specimen seldom has thesame porosity as the interior concrete. To reduce data scatter, measure-ments are
33、 made with the drying surfaces of replicate test specimens at thesame distance from the original exposed surface of the concrete.9. Sample Conditioning9.1 Specimens are to be in a saturated condition at the startof the test. Cure molded concrete cylinders for at least 28 daysin water storage tanks c
34、omplying with the requirements ofSpecification C511. Condition cores in accordance with 9.7.9.2 Seven days prior to the start of testing, cut test speci-mens to the necessary length and carry out steps 9.3 9.7.5Samson, E., and Marchand, J., “Modeling the Transport of Ions in UnsaturatedCement-Based
35、Materials,” Computers and Structures, Vol 85, No. 2324, 2007, pp.17401756.6Henchi, K., Samson, E., Chapdelaine, F., and Marchand, J., “AdvancedFinite-Element Predictive Model for the Service Life Prediction of ConcreteInfrastructures in Support ofAsset Management and Decision-Making,” Computingin Ci
36、vil Engineering, 2007, pp. 870880.C1792 1429.3 Use the caliper to measure four diameters distributeduniformly around the circumference of each end face. Measureeach diameter to the nearest 0.1 mm and calculate the averagediameter for the eight readings to the nearest 0.1 mm.9.4 Use the caliper to ma
37、ke four measurements of specimenlength approximately 90 apart. Measure each length to thenearest 0.1 mm and calculate the average length to the nearest0.1 mm.9.5 Dry the specimen side surface along its length withcompressed air until the surface is visibly dry. Seal the sidesurface of each specimen
38、with an impermeable material, asdescribed in 7.1, leaving the two end faces uncoated to act asdrying surfaces (Note 6).NOTE 6It is best practice to minimize the drying of the end facesduring the sealing operation. Moistened paper towels or sponges can beused to maintain the two end faces in a moiste
39、ned condition during thesealing process.9.6 After the sealing is completed and the coating has curedif applicable, measure and record the mass of each specimen tothe nearest 0.1 g.9.7 Immerse the sealed specimens for 7 days in watersaturated with calcium hydroxide. After 7 days of immersion,determin
40、e each specimen mass after removing surface water byblotting with an absorbent towel that has first been wettedthoroughly and wrung out (see 6.3). If the mass has changed bymore than 0.5 % from the mass determined in 9.6, repeat theimmersion for another 7 days. Continue this cyclic procedureof immer
41、sion and weighing until the mass variation is less than0.5 % between successive mass readings taken 7 days apart.10. Procedure10.1 Once the specimens have satisfied the immersion massgain criteria in 9.7, remove the saturated specimens from thelimewater one at a time and complete the initial mass me
42、a-surements on the removed specimen before proceeding to thenext one. For each removed specimen, to remove excesssurface water, blot all surfaces with absorbent towels that havefirst been wetted thoroughly and wrung out (see 6.3). Recordthe date and time of the beginning of the drying exposure forea
43、ch specimen.10.2 Measure and record the initial mass (mi) of eachspecimen to the nearest 0.1 g. After measuring its mass, placethe specimen into its exposure location within the dryingchamber. Maintain a minimum distance of 25 mm between thedrying surfaces of neighboring specimens.10.3 In the drying
44、 chamber, place each specimen on appro-priate supports so that air can move freely across both exposedsurfaces. Record temperature and relative humidity in at leasttwo different locations within 150 mm of the specimens.10.4 Record the mass change of the specimens by periodi-cally determining their m
45、ass after drying (mt) to the nearest 0.1g, using the same balance as in 10.2. Unless required otherwiseby the specifier of the tests, use the following measurementschedule:10.4.1 During Days14:One measurement per day at 246 2 h intervals,10.4.2 During Days513:Two measurements, one takenafter7dat1686
46、 2 h from the time of exposure to drying andthe other taken after 10 d at 240 6 2 h from the time ofexposure to drying, and10.4.3 At Day 14 and Beyond: One measurement per week(beginning on day 14) at 7 6 1 d intervals.10.5 Any time after four weeks of drying, terminate themonitoring of mass loss wh
47、en three successive weekly massmeasurements show less than 0.5 % variation from the imme-diately previous mass measurement.11. Calculation11.1 Calculate the cumulative mass loss in grams at anytime using the equation:Mt! 5 mi2 mt! (1)where:M(t) = the cumulative mass loss after drying at time t,g,mi=
48、 measured mass of the specimen prior to exposure todrying, g, andmt= measured mass of the specimen after drying at timet,g.11.2 Calculate the cumulative mass loss per unit exposedsurface area (two faces) at any time using the equation:Dt!5mi2 mt! d22!5Mt! d22!(2)where:D(t) = the cumulative mass loss
49、 per unit exposed surfacearea after drying at time t, g/mm2,mi= measured mass of the specimen prior to exposure todrying, g,mt= measured mass of the specimen after drying at timet,g,andd = average of all measured diameters of cylindricalspecimen tested (from 9.3), mm.11.3 Calculate the average temperature and relative humid-ity recorded during the time of the drying exposure byaveraging all of the readings acquired from the two locationsduring the actual time of drying exposure.12. Report12.1 Report the following:12.1.1 Date when concrete was samp
