ASTM C1761 C1761M-2013a Standard Specification for Lightweight Aggregate for Internal Curing of Concrete《混凝土内部固化用轻集料的标准规格》.pdf

1、Designation:C1761/C1761M13C1761/C1761M13a Standard Specication for Lightweight Aggregate for Internal Curing of Concrete 1 This standard is issued under the xed designation C1761/C1761M; the number immediately following the designation indicates the year of original adoption or, in the case of revis

2、ion, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval. 1. Scope 1.1 This specication covers lightweight aggregate intended to provide water for internal curing of con

3、crete. It includes test methods 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 and self-desiccation that can be signicant

4、contributors to early-age cracking. Appendix X1 provides guidance on calculating the quantity of lightweight aggregate 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 each system may not be exact equiva

5、lents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance. Some values have only SI units because the inch-pound equivalents are not used in practice. NOTE 2Sieve size is identied by its standard designation in Specica

6、tion E11. The alternative designation given in parentheses is for information only and does not represent a different standard sieve size. 1.3 The text of this standard references notes and footnotes that provide explanatory material. These notes and footnotes (excluding those in tables and gures) s

7、hall not be considered as requirements of the standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicabilit

8、y of regulatory limitations prior to use. 2. Referenced Documents 2.1 ASTM Standards: 2 C29/C29MTest Method for Bulk Density (Unit Weight”) and Voids in Aggregate C40Test Method for Organic Impurities in Fine Aggregates for Concrete C87Test Method for Effect of Organic Impurities in Fine Aggregate o

9、n Strength of Mortar C114Test Methods for Chemical Analysis of Hydraulic Cement C125Terminology Relating to Concrete and Concrete Aggregates C128Test Method for Density, Relative Density (Specic Gravity), and Absorption of Fine Aggregate C136Test Method for Sieve Analysis of Fine and Coarse Aggregat

10、es C142Test Method for Clay Lumps and Friable Particles in Aggregates C330/C330MSpecication for Lightweight Aggregates for Structural Concrete C641Test Method for Iron Staining Materials in Lightweight Concrete Aggregates C702Practice for Reducing Samples of Aggregate to Testing Size C1498Test Metho

11、d for Hygroscopic Sorption Isotherms of Building Materials C1608Test Method for Chemical Shrinkage of Hydraulic Cement Paste C1698Test Method for Autogenous Strain of Cement Paste and Mortar D75Practice for Sampling Aggregates E11Specication for Woven Wire Test Sieve Cloth and Test Sieves 1 This spe

12、cication is under the jurisdiction ofASTM Committee C09 on Concrete and ConcreteAggregates and is the direct responsibility of Subcommittee C09.21 on Lightweight Aggregates and Concrete. Current edition approved May 15, 2013June 15, 2013. Published July 2013August 2013. Originally approved in 2012.

13、Last previous edition approved in 20122013 as C1761/C1761M12.C1761/C1761M13. DOI: 10.1520/C1761_C1761M-13.10.1520/C1761_C1761M-13a. 2 ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatserviceastm.org.ForAnnualBookofASTMStandards volume information, refer to th

14、e standards Document Summary page on the ASTM website. This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because it may not be technically possible to adequately depict all changes ac

15、curately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version of the standard as published by ASTM is to be considered the official document. Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United

16、 States 13. Terminology 3.1 Denitions: 3.1.1 For denitions of terms used in this practice, refer to Terminology C125. 3.2 Denitions of Terms Specic to This Standard: 3.2.1 absorption, A 72 , nof lightweight aggregate, the increase in mass of a specimen of oven-dry lightweight aggregate due to water

17、penetrating into the permeable pores of the particles after being submerged for 72 h, expressed as percentage of oven-dry mass. 3.2.2 autogenous shrinkage, nreduction in volume due to chemical shrinkage of a sealed cementitious mixture, not subjected to external forces and under constant temperature

18、, measured from the time of nal setting. 3.2.2.1 Discussion The chemical shrinkage leads to emptying of the internal pores (see self-desiccation) that causes the formation of menisci in the partially water-lled pores. The menisci in turn give rise to internal tensile stresses that cause bulk shrinka

19、ge. While autogenous shrinkageisduetothechemicalshrinkage,themagnitudeofautogenousshrinkageislessthanthechemicalshrinkageaftersetting occurs,becausetheaggregateparticlesandthehydratedcementpastenetworkrestraintheshrinkage.Therestraintmayinturnlead to cracking. 3.2.3 chemical shrinkage, nthe reductio

20、n in volume of cementitious paste that occurs during hydration because the hydration products occupy less volume than the volume occupied originally by the water and unhydrated cementitious materials. 3.2.4 density (OD), nof lightweight aggregate, the mass of oven-dry lightweight aggregate particles

21、 per unit volume of aggregate particles, where the volume includes the permeable and impermeable pores within the particles but does not include the voids between the particles. 3.2.5 desorption, nof lightweight aggregate, the decrease in mass of lightweight aggregate originally containing absorbed

22、water due to water leaving the permeable pores as the aggregate attains moisture equilibrium with the surrounding environment maintained at constant temperature and a relative humidity less than 100%. 3.2.6 internal curing, nsupplying water within a cementitious mixture using pre-wetted lightweight

23、aggregate, or other materials 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 which the specimen of lightweight aggregate has been dried by heating

24、 in an oven at 1106 5 C 2306 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 the density of water at a stated temperature. 3.2.9 wetted surface-dry (WSD), adjrelated to lightweig

25、ht aggregate particles, the condition in which the permeable pores of lightweight aggregate particles are lled with water, to the extent achieved by submerging an oven-dry specimen for 72 h, and the surfaces of the particles are dry. 3.2.10 self-desiccation, nreduction in the internal relative humid

26、ity of a sealed cementitious mixture as a result of chemical shrinkage.mixture, due to chemical shrinkage, that may reduce the rate of hydration or stop hydration. 3.3 Symbols: A 72 =the 72-h absorption, expressed as a percentage of the oven-dry mass. G OD =relative density (oven-dry) of lightweight

27、 aggregate. G ODN =relative density (oven-dry) of normal weight aggregate. M LWA =calculated mass of oven-dry lightweight aggregate needed for internal curing per unit volume of concrete, kg/m 3 lb/yd 3 . M NWA =mass of normal weight aggregate in oven-dry condition to be removed, kg/m 3 lb/yd 3 . M

28、OD =mass of lightweight aggregate specimen in oven-dry condition, g. M PS =mass of pycnometer containing lightweight aggregate specimen and lled with water, g. M PW =mass of pycnometer lled with water, g. M SD =mass of lightweight aggregate specimen in wetted surface-dry condition, g. M 94 =equilibr

29、ium mass of aggregate originally in wetted surface-dry condition and subsequently stored at 94% relative humidity, g. C f =cementitious materials content of concrete mixture, kg/m 3 lb/yd 3 . CS=chemical shrinkage of cementitious material, expressed as kg water/kg of cement lb/lb (see Note 3). S=deg

30、ree 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. a max =maximum potential degree of hydration of cementitious materials expressed as a decimal fraction (0 to 1.0). C1761/C1761M13a 2W LWA =massofwater

31、releasedbylightweightaggregateingoingfromthewettedsurface-dryconditiontotheequilibriummass at 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 chemical shrinkage t

32、o calculate the required amount of lightweight aggregate for internal curing, the volume of water is converted to the mass of water. Hence chemical shrinkage is expressed as mass of water per unit mass of cement. 4. Ordering Information 4.1 The direct purchaser of lightweight aggregate for internal

33、curing shall include the following information in the purchase order as applicable. 4.1.1 Reference to this specication, as Specication C1761. 4.1.2 Whether the order is for ne aggregate, coarse aggregate, or combined ne and coarse aggregate. 4.1.3 Quantity in metric tons tons or cubic meters cubic

34、yards. 4.1.4 If the order is for coarse aggregate or combined ne and coarse aggregate, provide the nominal size designation as given in Table 1 or alternative grading as agreed between the purchaser and aggregate supplier. 4.1.5 Whether certication shall be furnished indicating that the material was

35、 sampled and tested in accordance with this specication 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 specication. 5. M

36、aterials and Manufacture 5.1 Two general types of lightweight aggregate are covered by this specication, as follows: 5.1.1 Aggregates produced by expanding, pelletizing, or sintering products such as blast-furnace slag, clay, diatomite, y ash, shale, or slate, and 5.1.2 Aggregate prepared by process

37、ing 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 Requirements 6.1 Organic ImpuritiesTest Method C40. Lightweight aggregate shall not produce a color darker than the standar

38、d color solution, unless it is demonstrated that when the aggregate is tested for the effect of organic impurities on strength of mortar, the relative strength at 7 days, determined in accordance with Test Method C87, is not less than 95%. 6.2 StainingTest Method C641. Lightweight aggregate shall pr

39、oduce a stain index of less than 60. Lightweight aggregate producingastainindexof60orhighershallbesubjecttorejectionifthedepositedstainisfounduponchemicalanalysistocontain an iron content, expressed as Fe 2 O 3 , equal to or greater than 1.5 mg/200 g of sample. 6.2.1 Loss on IgnitionTest Method C114

40、. The loss on ignition of lightweight aggregates shall not exceed 5%. NOTE4Someaggregatemaycontaincarbonatesorwaterofhydrationthatcontributetolossonignitionbutmaynotaffectthequalityoftheproduct. Therefore, when evaluating an aggregate, consideration should be given to the material characteristics th

41、at cause the ignition loss. 7. Physical Properties 7.1 ClayLumpsandFriableParticlesTestMethodC142.Thetotalamountofclaylumpsandfriableparticlesshallnotexceed 2% by dry mass. TABLE 1 Grading Requirements Nominal Size Designation Percentages (Mass) Passing Sieves Having Square Openings 25.0 mm (1 in.)

42、19.0 mm ( 3 4 in.) 12.5 mm ( 1 2 in.) 9.5 mm ( 3 8 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 m A (No. 200) Fine aggregate: 4.75 mm to 0 (No. 4 to 0) . . . . . . . . . 100 85100 . . . 4080 1035 525 . . . Coarse aggregate: 25.0 to 4.75 mm (1 in. to No. 4)

43、 95100 . . . 2560 . . . 010 . . . . . . . . . . . . 010 19.0 to 4.75 mm ( 3 4 in. to No.4) 100 90100 . . . 1050 015 . . . . . . . . . . . . 010 12.5 to 4.75 mm ( 1 2 in. to No. 4) . . . 100 90100 4080 540 020 010 . . . . . . 010 9.5 to 2.36 mm ( 3 8 in. to No. 8) . . . . . . 100 80100 540 020 010 .

44、. . . . . 010 Combined ne and coarse aggregate: 12.5 mm to 0 ( 1 2 in. to 0) . . . 100 95100 . . . 5080 . . . . . . 520 215 010 9.5 mm to 0 ( 3 8 in. to 0) . . . . . . 100 90100 6590 3565 . . . 1025 515 010 A The surfaces of pyro-processed lightweight aggregate particles ner than the 75 m (No. 200)

45、sieve are not deleterious and may be moderately pozzolanic. C1761/C1761M13a 37.2 GradingTest Method C136 as modied in Specication C330/C330M. The grading shall conform to the requirements shown in Table 1 or established by mutual agreement between interested parties. NOTE 5In general, a volume of li

46、ghtweight aggregate (ne or a combination of coarse and ne) for internal curing will replace an equal volume of normal weight aggregate in an existing conventional concrete mixture. The grading of the lightweight aggregate can be chosen to closely match the existing grading of the normal weight aggre

47、gates, or to ll in a gap in the existing normal weight aggregate grading, such as using a mid-range size lightweight aggregate to enhance the gradation of a gap-graded mixture (1). 3 7.2.1 Uniformity of GradingFor continuing shipments of ne aggregate from a given source, the neness modulus shall not

48、 vary more than 7% from the base neness modulus. The base neness modulus shall be that value that is typical of the source. The purchaser has the authority to approve a change in the base neness modulus. For coarse aggregate and combined ne and coarse aggregate, the uniformity of grading requirement

49、s of Specication C330/C330M shall apply. 7.3 Bulk DensityTest Method C29/C29M. The dry bulk density using the shoveling method of compaction shall conform to the requirements of Table 2 using a 14 L 1 2 ft 3 measure. 7.4 WaterAbsorptionThelightweightaggregateshallhavea72-habsorptionnotlessthan5%whentestedinaccordancewith Section 10. 7.5 DesorptionPropertiesThelightweightaggregateshallreleaseatleast85%ofitsabsorbedwaterat94%relativehumidity when t