1、Designation: C156 11C156 17Standard Test Method forWater Loss from a Mortar Specimen Through LiquidMembrane-Forming Curing Compounds for Concrete1This standard is issued under the fixed designation C156; the number immediately following the designation indicates the year oforiginal adoption or, in t
2、he case of revision, 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.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope*1.
3、1 This test method covers laboratory determination of the efficiencyability of liquid membrane-forming compounds for curingconcrete, as measured by their ability concrete to reduce moisture loss from mortar specimens during the early hardeningperiod.period as a measure of their applicability for cur
4、ing concrete.1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversionsto inch-pound units that are provided for information only and are not considered No other units of measurement are included inthis standard.1.3 This standard do
5、es not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.(WarningFresh hydraulic cementitious
6、mixtures are caustic and may cause chemical burns to skin andtissue upon prolonged exposure.)21.4 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standa
7、rds, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3C87 Test Method for Effect of Organic Impurities in Fine Aggregate on Strength of MortarC150 Specification for Portland CementC230/C230M Specif
8、ication for Flow Table for Use in Tests of Hydraulic CementC305 Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic ConsistencyC778 Specification for Standard SandD1475 Test Method For Density of Liquid Coatings, Inks, and Related ProductsD1653 Test Methods for Water Vap
9、or Transmission of Organic Coating FilmsD2369 Test Method for Volatile Content of CoatingsE178 Practice for Dealing With Outlying Observations3. Significance and Use3.1 The moisture retaining ability of a product as determined by this test method is used to assess the suitability of materialsfor con
10、tributing to an appropriate curing environment for concrete. The laboratory test method is used both in formulating and inspecifying or qualifying curing products. This test method gives the user a measure of the ability of tested curing materials toimpede the escape of moisturewater from a hydrauli
11、c cement mortar. Since it is desirable to retain moisturewater in fresh concreteto promote the hydration process, failure of the product to minimize the escape of moisturewater may lead to loss of strength,cracking, shrinkage, or low abrasion resistance of the hardened concrete, or a combination the
12、reof.1 This test method is under the jurisdiction of ASTM Committee C09 on Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee C09.22 onMaterials Applied to New Concrete Surfaces.Current edition approved June 1, 2011Aug. 1, 2017. Published June 2011September 2017. Origi
13、nally approved in 1940. Last previous edition approved in 20092011 asC156 09a.C156 11. DOI: 10.1520/C0156-11.10.1520/C0156-17.2 Section on Safety Precautions, Manual of Aggregate and Concrete Testing, Annual Book of ASTM Standards, Vol 04.02.3 For referencedASTM standards, visit theASTM website, www
14、.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of wha
15、t changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the
16、 official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2 Many factors affect the laboratory test results. Test results obtained may be highly variable as i
17、ndicated by the precisionstatement. Critical factors include the precision of the control of the temperature, humidity and air circulation in the curing cabinet,preparation and sealing of the mortar specimens, the age and surface condition of the mortar specimen when the curing productis applied, an
18、d the uniformity and quantity of application of the curing membrane.4. Apparatus4.1 Mechanical Mortar Mixer, as described in Practice C305, or a larger size mixture operating on the same principle.4.2 Flow Table, as described in Specification C230/C230M.4.3 Molds shall be made of metal, glass, hard
19、rubber, or plastic, and shall be watertight and rigidly constructed to preventdistortion during molding of the specimens or handling of the mold containing fresh mortar. They shall have a minimum surfacearea of 12000 mm2 (18.6 in., 2), and a minimum depth of 19 mm (mm. 34 in.).The top surface shall
20、be round, square, or rectangularwith length not more than twice the width. The top of the mold shall have a rim to provide a firm level surface to support the woodfloat and to facilitate the grooving and sealing steps of the procedure. The rim shall be parallel with the bottom surface of the mold.NO
21、TE 1Take care to avoid use of an excessive amount of oil, grease, or mold release compound on molds, particularly along the top rim where sealingcompound will be applied. Use of masking tape on the top rim during application of release compound to prevent contamination has been found expedient.4.4 S
22、poonA stainless steel serving spoon having a bowl 75 to 100 mm (3 to 4 in.) long and 50 to 75 mm (2 to 3 in.) widefor transferring the mortar from the mixing bowl to the mold.4.5 Gloves, of rubber or plastic, to be worn while molding the specimens.4.6 Tamper, of a nonabsorptive, nonabrasive material
23、 such as medium-hard rubber or seasoned oak rendered non-absorptive byimmersion for 15 min in paraffin at approximately 200 C.75 to 95C. The tamper shall be rectangular with a 25 by 50-mm (1 by2-in.) cross section and it shall be a convenient length (150 to 300 mm (6 to 12 in.).mm).4.7 Wood Float, a
24、pproximately 75 by 280 by 20 mm thick (3 by 11 by thick.34 in.).NOTE 2A commercial wood float equipped with a substantial handle can be readily reduced to these dimensions. The float shall be resurfaced orreplaced when there is noticeable wear to the floating surface.4.8 Brush, medium-soft bristle 5
25、0-mm (2-in.) paint brush to brush the surface of the specimens prior to sealing.4.9 Curing Cabinet, maintained at a temperature of 37.8 6 1.1C (1006 2 F) 1.1C and a relative humidity of 32 6 2 %. Thecuring cabinet shall be of a design that allows movement of conditioned air such that the solvent fro
26、m the curing compound willbe readily evaporated and eliminated from the system.Air flow over the specimens shall be adjusted to provide an evaporation rateof 2.0 to 3.4 g/h as measured by the procedure of Annex A1. The evaporation rate shall initially be measured for each positionin the cabinet in w
27、hich a specimen will be placed, and shall be verified annually and whenever any changes are made to the cabinet.The range of evaporation rates for all specimen positions in the test cabinet shall be reported.4.10 Balance, having the capacity to determine the mass of a filled specimen mold to the nea
28、rest 0.1 g or less.4.11 ApplicatorFor spray application, any apparatus that can be used to apply the curing compound uniformly and withminimum overspray is acceptable. For brush or roller application, use the equipment recommended by the curing compoundmanufacturer.5. Materials5.1 Portland Cement, c
29、onforming to the requirements for Type I of Specification C150.5.2 Graded Standard Sand, conforming to the requirements of Specification C778.5.3 Sealing Compound, that will not be affected by the curing material and which effectively seals against moisture loss betweenthe boundary of the specimen a
30、nd the edge of the mold.NOTE 3Tissue embedding wax, readily available from scientific supply houses, is a convenient and reliable sealant.6. Conditioning6.1 The temperature of the room and of all materials when used in this test shall be 23 6 2 C (73 6 4 F) 2C unless otherwisespecified, and the room
31、 humidity shall be 50 6 10 %.7. Number of Specimens7.1 A set of three or more test specimens shall be made in order to constitute a test of a given curing material.NOTE 4When more than one set of specimens is to be prepared, each set should be handled as a group throughout the preparation to make th
32、e elapsedtime between molding and application of the curing product as uniform as possible. This may require mixing the mortar for each set separately.7.2 For determining the quantity of curing compound to be applied (MA) calculate the total top surface area of the specimen,including the seal and th
33、e rim of the mold in square millimetres using appropriate geometric formulae.C156 172NOTE 5The area (A) used in calculating the mass loss per unit area (L) is calculated in 14.2 from the surface dimensions measured inside the sealof the specimen.8. Proportioning and Mixing Mortar8.1 ProportioningDet
34、ermine the sand content of the mortar by adding dry sand to a cement paste having a water-cement ratioof 0.40 by weight, to produce a flow of 35 6 5 in 10 drops of the flow table, following the procedure described in Test MethodC87. Discard the mix used to determine the proportion of sand to cement.
35、NOTE 6The sand:cement ratio required varies with the source of the cement.Aratio of 2.5:1 is suggested as a starting point. Flow may be determinedon a 3 to 4 kg batch of mortar which is conveniently mixed in the mixer described in Practice C305. The mixture used to establish the sand:cement ratiois
36、discarded because it is thought that the age and mixing history of the mortar affect the final moisture loss results and must be controlled.8.2 MixingCombine the components of the mortar in a mortar-mixing machine to produce a homogeneous mortar not morethan 6 min from the time the water and the cem
37、ent are combined.NOTE 7A generally effective sequence is to add the cement to all of the water in the mixing bowl and allow it to stand for 30 s. Then, mix at lowspeed for 30 s and, without stopping the mixer, add the sand within 30 s and continue mixing for 1 min. Stop the mixer for 1 min. During t
38、he first 15s, scrape down the sides of the bowl. Finish by mixing for an additional 1 min, and promptly begin molding the specimens.9. Preparing Specimens9.1 Thoroughly clean the molds before each use. Use of a mold release is acceptable provided that care is taken to avoidacceptable. Avoid its appl
39、ication to the top rim of the mold to prevent interference with sealing of the edge.9.2 Half fill the mold and spread the mortar with the back of the spoon to create a layer of approximately uniform thickness.Tamp over the entire surface with one stroke of the 25 by 50 mm (1 by 2 in.) 50 mm face of
40、the tamper per 1000 mm2 of surfacearea rounded to the nearest integer. Place a second layer of mortar, sufficient in amount to slightly overfill the mold and tamp ina similar manner. Using the 25-mm (1-in.) wide by 150 to 300-mm (6 to 12-in.) long edge of the tamper, fill the indentations madeby the
41、 tamping and level the surface by pressing down firmly with a series of contacts across the entire surface. Strike off thespecimen level with the top of the mold using a wood float with one pass only, in the direction of the long axis of the specimenfor rectangular molds, using a sawing motion of th
42、e float. Keep the 75-mm (3-in.) face of the float firmly in contact with the mortarand edges of the mold so that the float creates a uniformly dense surface free of voids and cracks.9.3 Immediately after molding, wipe Wipe the outside surfaces of the molds clean, and place the specimens in the curin
43、g cabinetmaintained at the conditions specified in 4.9. The specimens shall be level and not subject to vibration. The spacing between theindividual specimens and between the specimens and the side walls of the cabinet shall be between 50 and 175 mm (2 to 7 in.).mm. Within these limits the spacing s
44、hall be the same for all specimens. Use dummy specimens to fill any empty spaces in thecabinet.10. Surface Preparation and Edge Sealing10.1 Remove the specimens from the cabinet immediately upon disappearance of the surface water and lightly brush the surfaceusing just sufficient force to remove the
45、 laitance and glaze without scarifying the mortar surface. If surface water appears afterbrushing, return the specimen to the cabinet but immediately remove the specimen upon the disappearance of the surface waterbrought to the surface by the brushing operation, and brush again. The mortar shall be
46、free of surface water but shall not be drybelow the surface. The proper surface condition will be attained when brushing does not bring free water to the surface, or producesmearing, and can be determined by gently rubbing an area with the finger tip.NOTE 8The exposure time in the cabinet and the in
47、itial moisture loss that will result in the proper surface condition is characteristic of the curingcabinet used and other testing conditions related to the laboratory performing the test. Uniformity of test surface conditions may be maintained by settingan expected exposure time or initial moisture
48、 loss.When any test condition is changed (sand, cement, and so forth), a new exposure time or initial moistureloss, or both, shall be determined.10.2 Form a V-shaped groove approximately 3 mm (18 in.) deep and not more than 3 mm (18 in.) wide between the edge ofthe mortar specimen and the mold. Fill
49、 the groove with the sealing compound. The sealing compound shall not extend more than6 mm (14 in.) from the edge of the mold onto the surface of the specimen.NOTE 9To cut out the groove for sealing, the tip of a pointed trowel, a pointed spatula, a pointed triangular can opener, or a “hawksbill point” groundon the end of a spatula or knife blade have all been reported to be effective.11. Application of Curing Materials11.1 Determine the density of the curing compound, Dm, in accordance with Test Method D1475.11.2 Calculate the mass of the curing co
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