1、Designation: C156 09aStandard 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 the cas
2、e 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 Department of Defense.1. Scope*1.1 This test
3、 method covers laboratory determination of theefficiency of liquid membrane-forming compounds for curingconcrete, as measured by their ability to reduce moisture lossduring the early hardening period.1.2 The values stated in SI units are to be regarded asstandard. The values given in parentheses are
4、 mathematicalconversions to inch-pound units that are provided for informa-tion only and are not considered standard.1.3 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 standard to establish appro-priat
5、e safety and health practices and determine the applica-bility of regulatory limitations prior to use.(WarningFreshhydraulic cementitious mixtures are caustic and may causechemical burns to skin and tissue upon prolonged exposure.)22. Referenced Documents2.1 ASTM Standards:3C87 Test Method for Effec
6、t of Organic Impurities in FineAggregate on Strength of MortarC150 Specification for Portland CementC230/C230M Specification for Flow Table for Use in Testsof Hydraulic CementC305 Practice for Mechanical Mixing of Hydraulic CementPastes and Mortars of Plastic ConsistencyC778 Specification for Standa
7、rd SandD1475 Test Method For Density of Liquid Coatings, Inks,and Related ProductsD1653 Test Methods for Water Vapor Transmission ofOrganic Coating FilmsD2369 Test Method for Volatile Content of CoatingsE178 Practice for Dealing With Outlying Observations3. Significance and Use3.1 The moisture retai
8、ning ability of a product as deter-mined by this test method is used to assess the suitability ofmaterials for contributing to an appropriate curing environmentfor concrete. The laboratory test method is used both informulating and in specifying or qualifying curing products.This test method gives t
9、he user a measure of the ability oftested curing materials to impede the escape of moisture froma hydraulic cement mortar. Since it is desirable to retainmoisture in fresh concrete to promote the hydration process,failure of the product to minimize the escape of moisture maylead to loss of strength,
10、 cracking, shrinkage, or low abrasionresistance of the hardened concrete, or a combination thereof.3.2 Many factors affect the laboratory test results. Testresults obtained may be highly variable as indicated by theprecision statement. Critical factors include the precision of thecontrol of the temp
11、erature, humidity and air circulation in thecuring cabinet, preparation and sealing of the mortar speci-mens, the age and surface condition of the mortar specimenwhen the curing product is applied, and the uniformity andquantity of application of the curing membrane.4. Apparatus4.1 Mechanical Mortar
12、 Mixer, as described in PracticeC305, 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 rubber, orplastic, and shall be watertight and rigidly constructed toprevent distortion during molding
13、 of the specimens or handlingof the mold containing fresh mortar. They shall have aminimum surface area of 12000 mm2(18.6 in.2), and aminimum depth of 19 mm (34 in.). The top surface shall be1This test method is under the jurisdiction of ASTM Committee C09 onConcrete and ConcreteAggregates and is th
14、e direct responsibility of SubcommitteeC09.22 on Materials Applied to New Concrete Surfaces.Current edition approved Dec. 15, 2009. Published January 2010. Originallyapproved in 1940. Last previous edition approved in 2009 as C156 09. DOI:10.1520/C0156-09a.2Section on Safety Precautions, Manual of A
15、ggregate and Concrete Testing,Annual Book of ASTM Standards, Vol 04.02.3For 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 AST
16、M website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.round, square, or rectangular with length not more than twicethe width. The top of the mold shall have a rim
17、to provide afirm level surface to support the wood float and to facilitate thegrooving and sealing steps of the procedure. The rim shall beparallel with the bottom surface of the mold.NOTE 1Take care to avoid use of an excessive amount of oil, grease,or mold release compound on molds, particularly a
18、long the top rim wheresealing compound will be applied. Use of masking tape on the top rimduring application of release compound to prevent contamination has beenfound expedient.4.4 SpoonA stainless steel serving spoon having a bowl75 to 100 mm (3 to 4 in.) long and 50 to 75 mm (2 to 3 in.)wide for
19、transferring the mortar from the mixing bowl to themold.4.5 Gloves, of rubber or plastic, to be worn while moldingthe specimens.4.6 Tamper, of a nonabsorptive, nonabrasive material suchas medium-hard rubber or seasoned oak rendered non-absorptive by immersion for 15 min in paraffin at approxi-mately
20、 200 C. The tamper shall be rectangular with a 25 by50-mm (1 by 2-in.) cross section and it shall be a convenientlength (150 to 300 mm (6 to 12 in.).4.7 Wood Float, approximately 75 by 280 by 20 mm thick(3 by 11 by34 in.).NOTE 2A commercial wood float equipped with a substantial handlecan be readily
21、 reduced to these dimensions. The float shall be resurfacedor replaced when there is noticeable wear to the floating surface.4.8 Brush, medium-soft bristle 50-mm (2-in.) paint brush tobrush the surface of the specimens prior to sealing.4.9 Curing Cabinet, maintained at a temperature of 37.8 61.1C (1
22、006 2 F) and a relative humidity of 32 6 2 %. Thecuring cabinet shall be of a design that allows movement ofconditioned air such that the solvent from the curing compoundwill be readily evaporated and eliminated from the system. Airflow over the specimens shall be adjusted to provide anevaporation r
23、ate of 2.0 to 3.4 g/h as measured by the procedureof Annex A1. The evaporation rate shall initially be measuredfor each position in the cabinet in which a specimen will beplaced, and shall be verified annually and whenever anychanges are made to the cabinet. The range of evaporation ratesfor all spe
24、cimen positions in the test cabinet shall be reported.4.10 Balance, having the capacity to determine the mass ofa filled specimen mold to the nearest 0.1 g or less.4.11 ApplicatorFor spray application, any apparatus thatcan be used to apply the curing compound uniformly and withminimum overspray is
25、acceptable. For brush or roller applica-tion, use the equipment recommended by the curing compoundmanufacturer.5. Materials5.1 Portland Cement, conforming to the requirements forType I of Specification C150.5.2 Graded Standard Sand, conforming to the requirementsof Specification C778.5.3 Sealing Com
26、pound, that will not be affected by thecuring material and which effectively seals against moistureloss between the boundary of the specimen and the edge of themold.NOTE 3Tissue embedding wax, readily available from scientificsupply houses, is a convenient and reliable sealant.6. Conditioning6.1 The
27、 temperature of the room and of all materials whenused in this test shall be 23 6 2C(736 4 F) unlessotherwise specified, and the room humidity shall be 50 610 %.7. Number of Specimens7.1 A set of three or more test specimens shall be made inorder to constitute a test of a given curing material.NOTE
28、4When more than one set of specimens is to be prepared, eachset should be handled as a group throughout the preparation to make theelapsed time between molding and application of the curing product asuniform as possible. This may require mixing the mortar for each setseparately.7.2 For determining t
29、he quantity of curing compound to beapplied (MA) calculate the total top surface area of thespecimen, including the seal and the rim of the mold in squaremillimetres using appropriate geometric formulae.NOTE 5The area (A) used in calculating the mass loss per unit area(L) is calculated in 14.2 from
30、the surface dimensions measured inside theseal of the specimen.8. Proportioning and Mixing Mortar8.1 ProportioningDetermine the sand content of the mor-tar by adding dry sand to a cement paste having a water-cementratio of 0.40 by weight, to produce a flow of 35 6 5 in 10 dropsof the flow table, fol
31、lowing the procedure described in TestMethod C87. Discard the mix used to determine the proportionof sand to cement.NOTE 6The sand:cement ratio required varies with the source of thecement. A ratio of 2.5:1 is suggested as a starting point. Flow may bedetermined ona3to4kgbatch of mortar which is con
32、veniently mixed inthe mixer described in Practice C305. The mixture used to establish thesand:cement ratio is discarded because it is thought that the age andmixing history of the mortar affect the final moisture loss results and mustbe controlled.8.2 MixingCombine the components of the mortar in am
33、ortar-mixing machine to produce a homogeneous mortar notmore than 6 min from the time the water and the cement arecombined.NOTE 7A generally effective sequence is to add the cement to all ofthe water in the mixing bowl and allow it to stand for 30 s. Then, mix atlow speed for 30 s and, without stopp
34、ing the mixer, add the sand within30 s and continue mixing for 1 min. Stop the mixer for 1 min. During thefirst 15 s, scrape down the sides of the bowl. Finish by mixing for anadditional 1 min, and promptly begin molding the specimens.9. Preparing Specimens9.1 Thoroughly clean the molds before each
35、use. Use of amold release is acceptable provided that care is taken to avoidits application to the top rim of the mold to prevent interferencewith sealing of the edge.9.2 Half fill the mold and spread the mortar with the back ofthe spoon to create a layer of approximately uniform thickness.Tamp over
36、 the entire surface with one stroke of the 25 by 50mm (1 by 2 in.) face of the tamper per 1000 mm2of surfaceC156 09a2area rounded to the nearest integer. Place a second layer ofmortar, sufficient in amount to slightly overfill the mold andtamp in a similar manner. Using the 25-mm (1-in.) wide by 150
37、to 300-mm (6 to 12-in.) long edge of the tamper, fill theindentations made by the tamping and level the surface bypressing down firmly with a series of contacts across the entiresurface. Strike off the specimen level with the top of the moldusing a wood float with one pass only, in the direction of
38、thelong axis of the specimen for rectangular molds, using asawing motion of the float. Keep the 75-mm (3-in.) face of thefloat firmly in contact with the mortar and edges of the mold sothat the float creates a uniformly dense surface free of voidsand cracks.9.3 Immediately after molding, wipe the ou
39、tside surfaces ofthe molds clean, and place the specimens in the curing cabinetmaintained at the conditions specified in 4.9. The specimensshall be level and not subject to vibration. The spacing betweenthe individual specimens and between the specimens and theside walls of the cabinet shall be betw
40、een 50 and 175 mm (2 to7 in.). Within these limits the spacing shall be the same for allspecimens. Use dummy specimens to fill any empty spaces inthe cabinet.10. Surface Preparation and Edge Sealing10.1 Remove the specimens from the cabinet immediatelyupon disappearance of the surface water and ligh
41、tly brush thesurface using just sufficient force to remove the laitance andglaze without scarifying the mortar surface. If surface waterappears after brushing, return the specimen to the cabinet butimmediately remove the specimen upon the disappearance ofthe surface water brought to the surface by t
42、he brushingoperation, and brush again. The mortar shall be free of surfacewater but shall not be dry below the surface.The proper surfacecondition will be attained when brushing does not bring freewater to the surface, or produce smearing, and can be deter-mined by gently rubbing an area with the fi
43、nger tip.NOTE 8The exposure time in the cabinet and the initial moisture lossthat will result in the proper surface condition is characteristic of thecuring cabinet used and other testing conditions related to the laboratoryperforming the test. Uniformity of test surface conditions may bemaintained
44、by setting an expected exposure time or initial moisture loss.When any test condition is changed (sand, cement, and so forth), a newexposure time or initial moisture loss, 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 be
45、tween the edgeof the mortar specimen and the mold. Fill the groove with thesealing compound. The sealing compound shall not extendmore than 6 mm (14 in.) from the edge of the mold onto thesurface of the specimen.NOTE 9To cut out the groove for sealing, the tip of a pointed trowel,a pointed spatula,
46、a pointed triangular can opener, or a “hawksbill point”ground on the end of a spatula or knife blade have all been reported to beeffective.11. Application of Curing Materials11.1 Calculate the mass of the curing compound to beapplied, MA, to the nearest 0.1 g based on the specifiedapplication rate,
47、the total surface area calculated per 7.2, andthe density of the curing compound determined in accordancewith Test Method D1475. If no rate is specified, apply thecuring compound at the rate of 5.0 m2/L (200 ft2/gal). Themethod of application shall be in accordance with the manu-facturers recommenda
48、tions.11.2 Immediately after sealing, weigh the specimen to thenearest 0.1 g (M1); then uniformly apply the curing compoundat the specified rate of application. Application shall be madeexpeditiously to only one specimen at a time.NOTE 10It is desirable to use a spray booth or a laboratory hood toco
49、ntrol overspray and solvent fumes especially for curing compounds thatare sprayed. However, the velocity of air movement in the vicinity of thespecimen must be kept at a minimum so as to prevent, as much aspossible, significant loss of volatiles during spraying and before the finalweighing. Spraying shall be accomplished with the minimum pressure andflow rate of air with which an acceptable spray pattern can be attained.11.3 Determine the proper coverage by comparing the initialmass of the specimen (M1), before applying the curing com-pound, to the mass
