1、Designation: C156 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 the case
2、 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*1.1 This
3、test method covers laboratory determination of theability of liquid membrane-forming compounds for curingconcrete to reduce moisture loss from mortar specimens duringthe early hardening period as a measure of their applicabilityfor curing concrete.1.2 The values stated in SI units are to be regarded
4、 asstandard. No other units of measurement are included in thisstandard.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-priate safety and health practices and determine t
5、he applica-bility of regulatory limitations prior to use.(WarningFreshhydraulic cementitious mixtures are caustic and may causechemical burns to skin and tissue upon prolonged exposure.)21.4 This international standard was developed in accor-dance with internationally recognized principles on standa
6、rd-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3C87 Test Method for Effect of Organic Impuritie
7、s 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 Standard SandD1475 Test Meth
8、od For Density of Liquid Coatings, Inks,and Related ProductsD1653 Test Methods for Water Vapor Transmission of Or-ganic 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 pr
9、oduct 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 the user a measure of
10、 the ability oftested curing materials to impede the escape of water from ahydraulic cement mortar. Since it is desirable to retain water infresh concrete to promote the hydration process, failure of theproduct to minimize the escape of water may lead to loss ofstrength, cracking, shrinkage, or low
11、abrasion resistance of thehardened 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 temperature, humidity and air cir
12、culation in thecuring cabinet, preparation and sealing of the mortarspecimens, the age and surface condition of the mortar speci-men when the curing product is applied, and the uniformity andquantity of application of the curing membrane.4. Apparatus4.1 Mechanical Mortar Mixer, as described in Pract
13、iceC305, 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 of the specimens or handling
14、1This test method is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC09.22 on Materials Applied to New Concrete Surfaces.Current edition approved Aug. 1, 2017. Published September 2017. Originallyapproved in 1940. Last
15、previous edition approved in 2011 as C156 11. DOI:10.1520/C0156-17.2Section on Safety Precautions, Manual of Aggregate 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.or
16、g. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*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 StatesTh
17、is international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (
18、TBT) Committee.1of the mold containing fresh mortar. They shall have aminimum surface area of 12000 mm2, and a minimum depth of19 mm. The top surface shall be round, square, or rectangularwith length not more than twice the width. The top of the moldshall have a rim to provide a firm level surface t
19、o support thewood float and to facilitate the grooving and sealing steps ofthe procedure.The rim shall be parallel with the bottom surfaceof the mold.NOTE 1Take care to avoid use of an excessive amount of oil, grease,or mold release compound on molds, particularly along the top rim wheresealing comp
20、ound 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 long and 50 to 75 mm wide for transferring themortar from the mixing bowl to the mold.4.5
21、 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 75 to 95C.The tamper shall be rectangular with a 25 by 50-mm crosssection
22、 and it shall be a convenient length (150 to 300 mm).4.7 Wood Float, approximately 75 by 280 by 20 mm thick.NOTE 2A commercial wood float equipped with a substantial handlecan be readily reduced to these dimensions. The float shall be resurfacedor replaced when there is noticeable wear to the floati
23、ng surface.4.8 Brush, medium-soft bristle 50-mm paint brush to brushthe surface of the specimens prior to sealing.4.9 Curing Cabinet, maintained at a temperature of 37.8 61.1C and a relative humidity of 32 6 2 %. The curing cabinetshall be of a design that allows movement of conditioned airsuch that
24、 the solvent from the curing compound will be readilyevaporated and eliminated from the system. Air flow over thespecimens shall be adjusted to provide an evaporation rate of2.0 to 3.4 g/h as measured by the procedure of Annex A1. Theevaporation rate shall initially be measured for each position int
25、he cabinet in which a specimen will be placed, and shall beverified annually and whenever any changes are made to thecabinet. The range of evaporation rates for all specimenpositions in the test cabinet shall be reported.4.10 Balance, having the capacity to determine the mass ofa filled specimen mol
26、d 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 acceptable. For brush or rollerapplication, use the equipment recommended by the curingcompound manufacturer.5. Materials5.1 Portland
27、 Cement, conforming to the requirements forType I of Specification C150.5.2 Graded Standard Sand, conforming to the requirementsof Specification C778.5.3 Sealing Compound, that will not be affected by thecuring material and which effectively seals against moistureloss between the boundary of the spe
28、cimen and the edge of themold.NOTE 3Tissue embedding wax, readily available from scientificsupply houses, is a convenient and reliable sealant.6. Conditioning6.1 The temperature of the room and of all materials whenused in this test shall be 23 6 2C unless otherwise specified,and the room humidity s
29、hall be 50 6 10 %.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 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
30、 between molding and application of the curing product asuniform as possible. This may require mixing the mortar for each setseparately.7.2 For determining the quantity of curing compound to beapplied (MA) calculate the total top surface area of thespecimen, including the seal and the rim of the mol
31、d 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 the surface dimensions measured inside theseal of the specimen.8. Proportioning and Mixing Mortar8.1 ProportioningDetermine the sand content of
32、 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, following the procedure described in TestMethod C87. Discard the mix used to determine the proportionof sand to cement.NOTE 6The sand:cement ratio
33、 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 conveniently mixed inthe mixer described in Practice C305. The mixture used to establish thesand:cement ratio is discarded because it is thought t
34、hat 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 amortar-mixing machine to produce a homogeneous mortar notmore than 6 min from the time the water and the cement arecombined.NOTE 7A generally ef
35、fective 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 stopping 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
36、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 use. Use of amold release is acceptable. Avoid its application to the top rimof the mold to prevent interference with sealing of the edge.9.2 H
37、alf fill the mold and spread the mortar with the back ofthe spoon to create a layer of approximately uniform thickness.C156 172Tamp over the entire surface with one stroke of the 25 by50 mm face of the tamper per 1000 mm2of surface arearounded to the nearest integer. Place a second layer of mortar,s
38、ufficient in amount to slightly overfill the mold and tamp in asimilar manner. Using the 25-mm wide by 150 to 300-mm longedge of the tamper, fill the indentations made by the tampingand level the surface by pressing down firmly with a series ofcontacts across the entire surface. Strike off the speci
39、men levelwith the top of the mold using a wood float with one pass only,in the direction of the long axis of the specimen for rectangularmolds, using a sawing motion of the float. Keep the 75-mmface of the float firmly in contact with the mortar and edges ofthe mold so that the float creates a unifo
40、rmly dense surface freeof voids and cracks.9.3 Wipe the outside surfaces of the molds clean, and placethe specimens in the curing cabinet maintained at the condi-tions specified in 4.9. The specimens shall be level and notsubject to vibration. The spacing between the individualspecimens and between
41、the specimens and the side walls of thecabinet shall be between 50 and 175 mm. Within these limitsthe spacing shall be the same for all specimens. Use dummyspecimens to fill any empty spaces in the cabinet.10. Surface Preparation and Edge Sealing10.1 Remove the specimens from the cabinet upon disap-
42、pearance of the surface water and lightly brush the surfaceusing just sufficient force to remove the laitance and glazewithout scarifying the mortar surface. If surface water appearsafter brushing, return the specimen to the cabinet but immedi-ately remove the specimen upon the disappearance of thes
43、urface water brought to the surface by the brushing operation,and brush again. The mortar shall be free of surface water butshall 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-mi
44、ned by gently rubbing an area with the finger 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
45、test surface conditions may bemaintained 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 deepand not
46、 more than 3 mm wide between the edge of the mortarspecimen and the mold. Fill the groove with the sealingcompound. The sealing compound shall not extend more than6 mm from the edge of the mold onto the surface of thespecimen.NOTE 9To cut out the groove for sealing, the tip of a pointed trowel,a poi
47、nted spatula, 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 Determine the density of the curing compound, Dm, inaccordance with Test Method D1475.11.2 Calculate the ma
48、ss of the curing compound to beapplied, MA, to the nearest 0.1 g based on the specifiedapplication rate, the total surface area calculated in accordancewith 7.2, and the density of the curing compound, Dm. If norate is specified, apply the curing compound at the rate of5.0 m2/L. The method of applic
49、ation shall be in accordancewith the manufacturers recommendations.11.3 Weigh the specimen to the nearest 0.1 g (M1); thenuniformly apply the curing compound at the specified rate ofapplication. Application shall be made expeditiously to onlyone specimen at a time.NOTE 10It is desirable to use a spray booth or a laboratory hood tocontrol 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, signific
