1、Designation: C1761/C1761M 13aC1761/C1761M 13bStandard 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 re
2、vision, the year 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. Scope1.1 This specification covers lightweight aggregate intended to provide water for internal curing of c
3、oncrete. It includes testmethods for determining the absorption and desorption properties of lightweight aggregate.NOTE 1Internal curing provides an additional source of water to sustain hydration and substantially reduce the early-age autogenous shrinkage andself-desiccation that can be significant
4、 contributors to early-age cracking. Appendix X1 provides guidance on calculating the quantity of lightweightaggregate for internal curing.1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be exact equivale
5、nts; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance. Some values have only SI units because the inch-pound equivalents are not used inpractice.NOTE 2Sieve size is identified by its standard designation in Specificat
6、ion E11. The alternative designation given in parentheses is for informationonly and does not represent a different standard sieve size.1.3 The text of this standardspecification references notes and footnotes that provide explanatory material. These notes andfootnotes (excluding those in tables and
7、 figures) shall not be considered as requirements of the standard.1.4 This standardspecification does not purport to address all of the safety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appropriate safety and health practices and dete
8、rmine the applicability ofregulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C29/C29M Test Method for Bulk Density (“Unit Weight”) and Voids in AggregateC40 Test Method for Organic Impurities in Fine Aggregates for ConcreteC87 Test Method for Effect of Organic Impurities
9、in Fine Aggregate on Strength of MortarC114 Test Methods for Chemical Analysis of Hydraulic CementC125 Terminology Relating to Concrete and Concrete AggregatesC128 Test Method for Density, Relative Density (Specific Gravity), and Absorption of Fine AggregateC136 Test Method for Sieve Analysis of Fin
10、e and Coarse AggregatesC142 Test Method for Clay Lumps and Friable Particles in AggregatesC330/C330M Specification for Lightweight Aggregates for Structural ConcreteC641 Test Method for Iron Staining Materials in Lightweight Concrete AggregatesC702 Practice for Reducing Samples of Aggregate to Testi
11、ng SizeC1498 Test Method for Hygroscopic Sorption Isotherms of Building MaterialsC1608 Test Method for Chemical Shrinkage of Hydraulic Cement PasteC1698 Test Method for Autogenous Strain of Cement Paste and MortarD75 Practice for Sampling AggregatesE11 Specification for Woven Wire Test Sieve Cloth a
12、nd Test Sieves1 This specification is under the jurisdiction of ASTM Committee C09 on Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee C09.21 onLightweight Aggregates and Concrete.Current edition approved June 15, 2013Aug. 1, 2013. Published August 2013September 2013
13、. Originally approved in 2012. Last previous edition approved in 2013 asC1761/C1761M 13.C1761/C1761M 13a. DOI: 10.1520/C1761_C1761M-13a.10.1520/C1761_C1761M-13b.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of
14、 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 what changes have been made to the previous version. Becauseit may not be technicall
15、y 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 official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C7
16、00, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this practice, refer to Terminology C125.3.2 Definitions of Terms Specific to This Standard:3.2.1 absorption, A72, nof lightweight aggregate, the increase in mass of a specimen of
17、 oven-dry lightweight aggregate dueto water penetrating into the permeable pores of the particles after being submerged for 72 h, expressed as percentage of oven-drymass.3.2.2 autogenous shrinkage, nreduction in volume due to chemical shrinkage of a sealed cementitious mixture, not subjectedto exter
18、nal forces and under constant temperature, measured from the time of final setting.3.2.2.1 DiscussionThe chemical shrinkage leads to emptying of the internal pores (see self-desiccation) that causes the formation of menisci in thepartially water-filled pores. The menisci in turn give rise to interna
19、l tensile stresses that cause bulk shrinkage. While autogenousshrinkage is due to the chemical shrinkage, the magnitude of autogenous shrinkage is less than the chemical shrinkage after settingoccurs, because the aggregate particles and the hydrated cement paste network restrain the shrinkage. The r
20、estraint may in turn leadto cracking.3.2.3 chemical shrinkage, nthe reduction in volume of cementitious paste that occurs during hydration because the hydrationproducts occupy less volume than the volume occupied originally by the water and unhydrated cementitious materials.3.2.4 density (OD), nof l
21、ightweight aggregate, the mass of oven-dry lightweight aggregate particles per unit volume ofaggregate particles, where the volume includes the permeable and impermeable pores within the particles but does not include thevoids between the particles.3.2.5 desorption, nof lightweight aggregate, the de
22、crease in mass of lightweight aggregate originally containing absorbedwater due to water leaving the permeable pores as the aggregate attains moisture equilibrium with the surrounding environmentmaintained at constant temperature and a relative humidity less than 100 %.3.2.6 internal curing, nsupply
23、ing water within a cementitious mixture using pre-wetted lightweight aggregate, or othermaterials that readily release water from within the particles, thereby mitigating self-desiccation and sustaining hydration.3.2.7 oven-dry (OD), adjrelated to lightweight aggregate particles, the condition in wh
24、ich the specimen of lightweightaggregate has been dried by heating in an oven at 110 6 5 C 230 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 te
25、mperature.3.2.9 wetted surface-dry (WSD), adjrelated to lightweight aggregate particles, the condition in which the permeable pores oflightweight aggregate particles are filled with water, to the extent achieved by submerging an oven-dry specimen for 72 h, and thesurfaces of the particles are dry.3.
26、2.10 self-desiccation, nreduction in the internal relative humidity of a sealed cementitious mixture, due to chemicalshrinkage, that may reduce the rate of hydration or stop hydration.3.3 Symbols:A72 = the 72-h absorption, expressed as a percentage of the oven-dry mass.GOD = relative density (oven-d
27、ry) of lightweight aggregate.GODN = relative density (oven-dry) of normal weight aggregate.MLWA = calculated mass of oven-dry lightweight aggregate needed for internal curing per unit volume of concrete,kg/m3 lb/yd3.MNWA = mass of normal weight aggregate in oven-dry condition to be removed, kg/m3 lb
28、/yd3.MOD = mass of lightweight aggregate specimen in oven-dry condition, g.MPS = mass of pycnometer containing lightweight aggregate specimen and filled with water, g.MPW = mass of pycnometer filled with water, g.MSD = mass of lightweight aggregate specimen in wetted surface-dry condition, g.M94 = e
29、quilibrium mass of aggregate originally in wetted surface-dry condition and subsequently stored at 94 % relativehumidity, g.Cf = cementitious materials content of concrete mixture, kg/m3 lb/yd3.CS = chemical shrinkage of cementitious material, expressed as kg water/kg of cement lb/lb (see Note 3).S
30、= degree of saturation of lightweight aggregate relative to wetted surface-dry condition (0 to 1.0).w/cm = water-cementitious materials ratio, kg/kg lb/lb.max = maximum potential degree of hydration of cementitious materials expressed as a decimal fraction (0 to 1.0).C1761/C1761M 13b2WLWA = mass of
31、water released by lightweight aggregate in going from the wetted surface-dry condition to the equilibrium massat a relative humidity of 94 %, expressed as a fraction of the oven-dry mass.NOTE 3Chemical shrinkage is measured in units of volume of water per unit mass of cement. In using the value of c
32、hemical shrinkage to calculatethe required amount of lightweight aggregate for internal curing, the volume of water is converted to the mass of water. Hence chemical shrinkage isexpressed as mass of water per unit mass of cement.4. Ordering Information4.1 The direct purchaser of lightweight aggregat
33、e for internal curing shall include the following information in the purchaseorder as applicable.4.1.1 Reference to this specification, as Specification C1761.4.1.2 Whether the order is for fine aggregate, coarse aggregate, or combined fine and coarse aggregate.4.1.3 Quantity in metric tons tons or
34、cubic meters cubic yards.4.1.4 If the order is for coarse aggregate or combined fine and coarse aggregate, provide the nominal size designation as givenin Table 1 or alternative grading as agreed between the purchaser and aggregate supplier.4.1.5 Whether certification shall be furnished indicating t
35、hat the material was sampled and tested in accordance with thisspecification and found to meet the requirements.4.1.6 Whether a report of the results of aggregate tests shall be furnished.4.1.7 Whether the results of tests of concrete properties are required.4.1.8 Any exceptions or additions to this
36、 specification.5. Materials and Manufacture5.1 Two general types of lightweight aggregate are covered by this specification, as follows:5.1.1 Aggregates produced by expanding, pelletizing, or sintering products such as blast-furnace slag, clay, diatomite, fly ash,shale, or slate, and5.1.2 Aggregate
37、prepared by processing natural materials, such as pumice, scoria, and tuff.5.2 The aggregate shall be composed predominately of lightweight-cellular and granular inorganic materials.6. Chemical Requirements6.1 Organic ImpuritiesTest Method C40. Lightweight aggregate shall not produce a color darker
38、than the standard colorsolution, unless it is demonstrated that when the aggregate is tested for the effect of organic impurities on strength of mortar, therelative strength at 7 days, determined in accordance with Test Method C87, is not less than 95 %.6.2 StainingTest Method C641. Lightweight aggr
39、egate shall produce a stain index of less than 60. Lightweight aggregateproducing a stain index of 60 or higher shall be subject to rejection if the deposited stain is found upon chemical analysis to containan iron content, expressed as Fe2O3, equal to or greater than 1.5 mg/200 g of sample.6.2.1 Lo
40、ss on IgnitionTest Method C114. The loss on ignition of lightweight aggregates shall not exceed 5 %.NOTE 4Some aggregate may contain carbonates or water of hydration that contribute to loss on ignition but may not affect the quality of the product.Therefore, when evaluating an aggregate, considerati
41、on should be given to the material characteristics that cause the ignition loss.7. Physical Properties7.1 Clay Lumps and Friable ParticlesTest Method C142. The total amount of clay lumps and friable particles shall not exceed2 % by dry mass.TABLE 1 Grading RequirementsNominal Size DesignationPercent
42、ages (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 mm(No. 4)2.36 mm(No. 8)1.18 mm(No. 160)300 m(No. 50)150 m(No. 100)75 mA(No. 200)Fine aggregate:4.75 mm to 0 (No. 4 to 0) . . . . . . . . . 100 85100 . . . 4080 1035 525 . . .Coarse aggrega
43、te:25.0 to 4.75 mm (1 in. to No. 4) 95100 . . . 2560 . . . 010 . . . . . . . . . . . . 01019.0 to 4.75 mm (34 in. to No.4) 100 90100 . . . 1050 015 . . . . . . . . . . . . 01012.5 to 4.75 mm (12 in. to No. 4) . . . 100 90100 4080 540 020 010 . . . . . . 0109.5 to 2.36 mm (38 in. to No. 8) . . . . .
44、. 100 80100 540 020 010 . . . . . . 010Combined fine and coarse aggregate:12.5 mm to 0 (12 in. to 0) . . . 100 95100 . . . 5080 . . . . . . 520 215 0109.5 mm to 0 (38 in. to 0) . . . . . . 100 90100 6590 3565 . . . 1025 515 010A The surfaces of pyro-processed lightweight aggregate particles finer th
45、an the 75 m (No. 200) sieve are not deleterious and may be moderately pozzolanic.C1761/C1761M 13b37.2 GradingTest Method C136 as modified in Specification C330/C330M. The grading shall conform to the requirementsshown in Table 1 or established by mutual agreement between interested parties.NOTE 5In
46、general, a volume of lightweight aggregate (fine or a combination of coarse and fine) for internal curing will replace an equal volume ofnormal weight aggregate in an existing conventional concrete mixture. The grading of the lightweight aggregate can be chosen to closely match theexisting grading o
47、f the normal weight aggregates, or to fill in a gap in the existing normal weight aggregate grading, such as using a mid-range sizelightweight aggregate to enhance the gradation of a gap-graded mixture (1).37.2.1 Uniformity of GradingFor continuing shipments of fine aggregate from a given source, th
48、e fineness modulus shall notvary more than 7 % from the base fineness modulus. The base fineness modulus shall be that value that is typical of the source.The purchaser has the authority to approve a change in the base fineness modulus. For coarse aggregate and combined fine andcoarse aggregate, the
49、 uniformity of grading requirements of Specification C330/C330M shall apply.7.3 Bulk DensityTest Method C29/C29M. The dry bulk density using the shoveling method of compaction shall conform tothe requirements of Table 2 using a 14 L 12 ft3 measure.7.4 Water AbsorptionThe lightweight aggregate shall have a 72-h absorption not less than 5 % when tested in accordance withSection 10.7.5 Desorption PropertiesThe lightweight aggregate shall release at least 85 % of its absorbed water at 94 %
