ASTM_C_1151_-_91.pdf

Designation:C 1151 91Standard Test Method forEvaluating the Effectiveness of Materials for CuringConcrete1This standard is issued under the fixed designation C 1151;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year 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 laboratory determination of theefficiency of liquid membrane-forming compounds and sheetmaterials for curing concrete.This test method can also beuseful in research work where the effect of different variableson the curing of concrete is studied.1.2 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationalpurposes only.1.3 This standard does not purport to address all of thesafety problems,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:C 87 Test Method for Effect of Organic Impurities in FineAggregate on Strength of Mortar2C 150 Specification for Portland Cement3C 511 Specification for Moist Cabinets,Moist Rooms andWater Storage Tanks Used in the Testing of HydraulicCements and Concretes3C 670 Practice for Preparing Precision and Bias Statementsfor Test Methods of Construction Materials2C 778 Specification for Standard Sand33.Summary of Test Method3.1 Three slabs of a standard mortar are molded and after 4h,one is covered with the curing material to be tested,thesecond is tightly sealed with an impermeable lid,and the thirdis left uncovered.All three molds are stored in a test environ-ment for 3 days.The test environment may be any set ofconditions selected by the tester,provided only that a minimumrate of evaporation from a free-water surface of 0.4 kg/m2/h bemaintained.3.2 At the conclusion of the storage period,the slabs aredemolded and three 25-mm(1-in.)diameter cores are cut atrandom from each of the slabs and stored under methanol forat least 24 h to stop the hydration of the cement and displacewater.Using a diamond-blade saw and ethanol as coolant,thetop surface of each core is then sliced off,and from theremaining core,1-cm(0.39-in.)thick disks are cut from the topand the bottom,then placed in a vacuum desiccator for 24 h.3.3 The absorptivity of each dried disk is determined byweighing it before and after a 60-s contact of its top surfacewith a water-saturated stack of filter paper.The difference inabsorbtivity of the top and bottom disks is a measure of theeffectiveness of the curing.4.Significance and Use4.1 This is an end result oriented test method.The effec-tiveness of a given curing material at a given environmentalcondition is determined by comparing the quality of the surfaceregion of a 90.0-mm(3.5-in.)thick mortar specimen with thequality of the well-protected bottom region of the samespecimen.The underlying assumption is that the bottom regionof a 90.0-mm(3.5-in.)thick specimen is little affected by theenvironmental conditions at the surface that can cause rapidevaporation of water.The quality of the mortar is determinedby the degree to which the pore structure of the cement pastehas become less open due to proper hydration of the cement asindicated by the absorptivity of the mortar.5.Apparatus5.1 Mortar Mixer,power-driven,capable of thoroughlymixing batches of the prescribed size(approximately12ft3for3 test slabs)at the prescribed consistency.A revolving drumtilting mixer,a revolving pan or a revolving paddle mixer maybe satisfactory.1This test method is under the jurisdiction ofASTM Committee C-9 on Concreteand ConcreteAggregates and is the direct responsibility of Subcommittee C09.22 onCuring Materials.Current edition approved Oct.15,1991.Published December 1991.Originallypublished as information only in P 198.Last previous edition C 1151 90.2Annual Book of ASTM Standards,Vol 04.02.3Annual Book of ASTM Standards,Vol 04.01.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.NOTICE:This standard has either been superseded and replaced by a new version or withdrawn.Contact ASTMInternational(www.astm.org)for the latest information.5.2 Molds and Lid,watertight,made of metal,glass,hardrubber,or plastic.The molds shall be approximately 310 by165 mm(1214by 612in.)in horizontal cross-section and 90 63 mm(312618in.)deep.For a set of three molds,one lid shallbe available.5.3 Balances:5.3.1 The balance or scale for determining the mass of thetest specimens shall have a capacity of 50 g or more,sensitiveto 0.0001 g or less,and accurate within 0.01%of the test massat any point within the range of use for this test.5.3.2 The balance or scale used for determining the mass ofthe curing compound,where cu