1、Designation: C1761/C1761M 17Standard Specification forLightweight Aggregate for Internal Curing of Concrete1This standard is issued under the fixed designation C1761/C1761M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision, the year
2、of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This specification covers lightweight aggregate intendedto provide water for internal curing of concrete. It inclu
3、des testmethods for determining the absorption and desorption prop-erties of lightweight aggregate.NOTE 1Internal curing provides an additional source of water tosustain hydration and substantially reduce the early-age autogenousshrinkage and self-desiccation that can be significant contributors toe
4、arly-age cracking. Appendix X1 provides guidance on calculating thequantity of lightweight aggregate for internal curing.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eac
5、hsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformance.Some values have only SI units because the inch-poundequivalents are not used in practice.NOTE 2Sieve size is identified by its standard designation in Speci-fication E11. The alterna
6、tive designation given in parentheses is forinformation only and does not represent a different standard sieve size.1.3 The text of this specification references notes andfootnotes that provide explanatory material. These notes andfootnotes (excluding those in tables and figures) shall not beconside
7、red as requirements of the standard.1.4 This specification 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 the applica-bility of regulatory
8、 limitations prior to use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organiz
9、ation TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C29/C29M Test Method for Bulk Density (“Unit Weight”)and Voids in AggregateC40/C40M Test Method for Organic Impurities in FineAggregates for ConcreteC87/C87M Test Method for Effect of Organic Impurities inFin
10、e Aggregate on Strength of MortarC114 Test Methods for Chemical Analysis of HydraulicCementC125 Terminology Relating to Concrete and Concrete Ag-gregatesC128 Test Method for Relative Density (Specific Gravity)and Absorption of Fine AggregateC136/C136M Test Method for Sieve Analysis of Fine andCoarse
11、 AggregatesC142/C142M Test Method for Clay Lumps and FriableParticles in AggregatesC330/C330M Specification for Lightweight Aggregates forStructural ConcreteC641 Test Method for Iron Staining Materials in Light-weight Concrete AggregatesC702/C702M Practice for Reducing Samples of Aggregateto Testing
12、 SizeC1498 Test Method for Hygroscopic Sorption Isotherms ofBuilding MaterialsC1608 Test Method for Chemical Shrinkage of HydraulicCement PasteC1698 Test Method for Autogenous Strain of Cement Pasteand MortarD75/D75M Practice for Sampling AggregatesE11 Specification for Woven Wire Test Sieve Cloth a
13、nd TestSieves3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this practice, refer toTerminology C125.3.2 Definitions of Terms Specific to This Standard:1This specification is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct respon
14、sibility of SubcommitteeC09.21 on Lightweight Aggregates and Concrete.Current edition approved June 15, 2017. Published July 2017. Originallyapproved in 2012. Last previous edition approved in 2015 as C1761/C1761M 15.DOI: 10.1520/C1761_C1761M-17.2For referenced ASTM standards, visit the ASTM website
15、, 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 ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Driv
16、e, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis 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 iss
17、ued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2.1 absorption, A72,nof lightweight aggregate, the in-crease in mass of a specimen of oven-dry lightweight aggregatedue to water penetrating into the permeable pores of theparticles after being submerged for 72 h, exp
18、ressed as percent-age of oven-dry mass.3.2.2 autogenous shrinkage, nreduction in volume due tochemical shrinkage of a sealed cementitious mixture, notsubjected to external forces and under constant temperature,measured from the time of final setting.3.2.2.1 DiscussionThe chemical shrinkage leads to
19、emp-tying of the internal pores (see self-desiccation) that causes theformation of menisci in the partially water-filled pores. Themenisci in turn give rise to internal tensile stresses that causebulk shrinkage. While autogenous shrinkage is due to thechemical shrinkage, the magnitude of autogenous
20、shrinkage isless than the chemical shrinkage after setting occurs, becausethe aggregate particles and the hydrated cement paste networkrestrain the shrinkage. The restraint may in turn lead tocracking.3.2.3 chemical shrinkage, nthe reduction in volume ofcementitious paste that occurs during hydratio
21、n because thehydration products occupy less volume than the volumeoccupied originally by the water and unhydrated cementitiousmaterials.3.2.4 density (OD), nof lightweight aggregate, the mass ofoven-dry lightweight aggregate particles per unit volume ofaggregate particles, where the volume includes
22、the permeableand impermeable pores within the particles but does notinclude the voids between the particles.3.2.5 desorption (D), nof lightweight aggregate, the de-crease in mass of lightweight aggregate originally containingabsorbed water due to water leaving the permeable pores as theaggregate att
23、ains moisture equilibrium with the surroundingenvironment maintained at constant temperature and a relativehumidity less than 100 %, and expressed as a percentage of the72-h absorption.3.2.6 internal curing, nsupplying water within a cemen-titious mixture using pre-wetted lightweight aggregate, or o
24、thermaterials that readily release water from within the particles,thereby mitigating self-desiccation and sustaining hydration.3.2.7 oven-dry (OD), adjrelated to lightweight aggregateparticles, the condition in which the specimen of lightweightaggregate has been dried by heating in an oven at 110 6
25、 5C230 6 10 F for sufficient time to reach a constant mass.3.2.8 relative density, (OD), nof lightweight aggregate,the ratio of the density (OD) of the lightweight aggregate to thedensity of water at a stated temperature.3.2.9 wetted surface-dry (WSD), adjrelated to lightweightaggregate particles, t
26、he condition in which the permeablepores of lightweight aggregate particles are filled with water, tothe extent achieved by submerging an oven-dry specimen for72 h, and the surfaces of the particles are dry.3.2.10 self-desiccation, nreduction in the internal relativehumidity of a sealed cementitious
27、 mixture, due to chemicalshrinkage, that may reduce the rate of hydration or stophydration.3.3 Symbols: A72= the 72-h absorption, expressed as apercentage of the oven-dry mass.D = the desorption, expressed as a percentage of the A72absorption.GOD= relative density (oven-dry) of lightweight aggregate
28、.GODN= relative density (oven-dry) of normal weight aggre-gate.MLWA= calculated mass of oven-dry lightweight aggregateneeded for internal curing per unit volume of concrete,kg/m3lb yd3.MNWA= mass of normal weight aggregate in oven-dry con-dition to be removed, kg/m3lb yd3.MOD= mass of lightweight ag
29、gregate specimen in oven-drycondition, g.MPS= mass of pycnometer containing lightweight aggregatespecimen and filled with water, g.MPW= mass of pycnometer filled with water, g.MSD= mass of lightweight aggregate specimen in wettedsurface-dry condition, g.M94= equilibrium mass of aggregate originally
30、in wettedsurface-dry condition and subsequently stored at 94 % relativehumidity, g.Cf= cementitious materials content of concrete mixture,kg/m3lb yd3.CS = chemical shrinkage of cementitious material, expressedas kg water/kg of cement lb/lb (see Note 3).S = degree of saturation of lightweight aggrega
31、te relative towetted surface-dry condition (0 to 1.0).w/cm = water-cementitious materials ratio, kg/kg lb/lb.max= maximum potential degree of hydration of cementi-tious materials expressed as a decimal fraction (0 to 1.0).WLWA= mass of water released by lightweight aggregate ingoing from the wetted
32、surface-dry condition to the equilibriummass at a relative humidity of 94 %, expressed as a fraction ofthe oven-dry mass.NOTE 3Chemical shrinkage is measured in units of volume of waterper unit mass of cement. In using the value of chemical shrinkage tocalculate the required amount of lightweight ag
33、gregate for internal curing,the volume of water is converted to the mass of water. Hence chemicalshrinkage is expressed as mass of water per unit mass of cement.4. Ordering Information4.1 The direct purchaser of lightweight aggregate for inter-nal curing shall include the following information in th
34、epurchase order as applicable.4.1.1 Reference to this specification, as SpecificationC1761.4.1.2 Whether the order is for fine aggregate, coarseaggregate, or combined fine and coarse aggregate.4.1.3 Quantity in metric tons tons or cubic meters cubicyards.4.1.4 If the order is for coarse aggregate or
35、 combined fineand coarse aggregate, provide the nominal size designation asgiven in Table 1 or alternative grading as agreed between thepurchaser and aggregate supplier.4.1.5 Whether certification shall be furnished indicating thatthe material was sampled and tested in accordance with thisspecificat
36、ion and found to meet the requirements.C1761/C1761M 1724.1.6 Whether a report of the results of aggregate tests shallbe furnished.4.1.7 Whether the results of tests of concrete properties arerequired.4.1.8 Any exceptions or additions to this specification.5. Materials and Manufacture5.1 Two general
37、types of lightweight aggregate are coveredby this specification, as follows:5.1.1 Aggregates produced by expanding, pelletizing, orsintering products such as blast-furnace slag, clay, diatomite,fly ash, shale, or slate, and5.1.2 Aggregate prepared by processing natural materials,such as pumice, scor
38、ia, and tuff.5.2 The aggregate shall be composed predominately oflightweight-cellular and granular inorganic materials.6. Chemical Requirements6.1 Organic ImpuritiesTest Method C40/C40M. Light-weight aggregate shall not produce a color darker than thestandard color solution, unless it is demonstrate
39、d that when theaggregate is tested for the effect of organic impurities onstrength of mortar, the relative strength at 7 days, determined inaccordance with Test Method C87/C87M, is not less than95 %.6.2 StainingTest Method C641. Lightweight aggregateshall produce a stain index of less than 60. Light
40、weightaggregate producing a stain index of 60 or higher shall besubject to rejection if the deposited stain is found uponchemical analysis to contain an iron content, expressed asFe2O3, equal to or greater than 1.5 mg/200 g of sample.6.2.1 Loss on IgnitionTest Method C114. The loss onignition of lig
41、htweight aggregates shall not exceed 5 %.NOTE 4Some aggregate may contain carbonates or water of hydrationthat contribute to loss on ignition but may not affect the quality of theproduct. Therefore, when evaluating an aggregate, consideration should begiven to the material characteristics that cause
42、 the ignition loss.7. Physical Properties7.1 Clay Lumps and Friable ParticlesTest Method C142/C142M. The total amount of clay lumps and friable particlesshall not exceed 2 % by dry mass.7.2 GradingTest Method C136/C136M as modified inSpecification C330/C330M. The grading shall conform to therequirem
43、ents shown in Table 1 or established by mutualagreement between interested parties.NOTE 5In general, a volume of lightweight aggregate (fine or acombination of coarse and fine) for internal curing will replace an equalvolume of normal weight aggregate in an existing conventional concretemixture. The
44、 grading of the lightweight aggregate can be chosen to closelymatch the existing grading of the normal weight aggregates, or to fill in agap in the existing normal weight aggregate grading, such as using amid-range size lightweight aggregate to enhance the gradation of agap-graded mixture (1).37.2.1
45、 Uniformity of GradingFor continuing shipments offine aggregate from a given source, the fineness modulus shallnot vary more than 7 % from the base fineness modulus. Thebase fineness modulus shall be that value that is typical of thesource. The purchaser has the authority to approve a change inthe b
46、ase fineness modulus. For coarse aggregate and combinedfine and coarse aggregate, the uniformity of grading require-ments of Specification C330/C330M shall apply.7.3 Bulk DensityTest Method C29/C29M. The dry bulkdensity using the shoveling method of compaction shallconform to the requirements of Tab
47、le 2 using a 14 L 12 ft3measure.7.4 Water AbsorptionThe lightweight aggregate shallhave a 72-h absorption not less than 5 % when tested inaccordance with Section 10.7.5 Desorption PropertiesThe lightweight aggregate shallrelease at least 85 % of its absorbed water at 94 % relativehumidity when teste
48、d in accordance with Section 11.3The boldface numbers in parentheses refer to the list of references at the end ofthis standard.TABLE 1 Grading RequirementsNominal Size DesignationPercentages (Mass) Passing Sieves Having Square Openings25.0 mm(1 in.)19.0 mm(34 in.)12.5 mm(12 in.)9.5 mm(38 in.)4.75 m
49、m(No. 4)2.36 mm(No. 8)1.18 mm(No. 16)300 m(No. 50)150 m(No. 100)75 mA(No. 200)Fine aggregate:4.75 mm to 0 (No. 4 to 0) . . . . . . . . . 100 65100 . . . 1580 035 025 . . .Coarse aggregate:25.0 to 4.75 mm (1 in. to No. 4) 95100 . . . 2560 . . . 010 . . . . . . . . . . . . 01019.0to4.75mm(34 in. to No.4) 100 90100 . . . 1050 015 . . . . . . . . . . . . 01012.5to4.75mm(12 in. to No. 4) . . . 100 90100 4080 540 020 010 . . . . . . 0109.5to2.36mm(38 in. to No. 8) . . . . . . 100 80100 540 020 010 .
