1、Designation: C1798/C1798M 161Standard Specification forReturned Fresh Concrete for Use in a New Batch of Ready-Mixed Concrete1This standard is issued under the fixed designation C1798/C1798M; the number immediately following the designation indicates theyear of original adoption or, in the case of r
2、evision, 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.1NOTEThe designation was editorially corrected to match the units of measurement statement in October 2016.1.
3、 Scope1.1 This specification covers returned fresh concrete for usein a new batch of ready-mixed concrete. Requirements forreturned fresh concrete shall be either as hereinafter specifiedor as specified by the purchaser. In any case where therequirements of the purchaser differ from those in thisspe
4、cification, the purchasers requirements shall govern. Thisspecification does not cover the placement, consolidation,curing, or protection of the concrete after delivery to thepurchaser.1.2 This specification by itself shall not grant permission tothe manufacturer to use returned fresh concrete in a
5、new batchof concrete.NOTE 1The permission to use returned fresh concrete may beaddressed in purchase documents, which may reference this specification.1.3 Returned fresh concrete in a quantity of less than 450 kg1000 lb or 0.2 m30.25 yd3 shall not be subject to thisspecification.1.4 The values state
6、d 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, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in nonconformancewith the standard.1.5 The
7、text of this standard references notes and footnotes,which provide explanatory information. These notes and foot-notes shall not be considered as requirements of the standard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibi
8、lity 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. (WarningFreshhydraulic cementitious mixtures are caustic and may causechemical burns to skin and tissue upon prolonged use.2)2. Referenced
9、Documents2.1 ASTM Standards:3C94/C94M Specification for Ready-Mixed ConcreteC125 Terminology Relating to Concrete and Concrete Ag-gregatesC494/C494M Specification for Chemical Admixtures forConcreteC1064/C1064M Test Method for Temperature of FreshlyMixed Hydraulic-Cement Concrete3. Terminology3.1 De
10、finitionsThe terms used in this specification aredefined in Terminology C125.3.2 Definitions of Terms Specific to This Standard:3.2.1 admixture, hydration stabilizing, nset-retardingadmixture, conforming to Specification C494/C494M Type Bor D, that can predictably reduce the hydration rate of cement
11、for applications requiring the management of time of setting ofreturned concrete, reducing the hydration rate of cement finesin water from concrete production, or for applications requiringextended delivery time of ready-mixed concrete.3.2.2 concrete, returned fresh, nfresh concrete not yetdischarge
12、d from a ready-mixed concrete transportation unitwhen it is returned to the manufacturer.4. Ordering Information4.1 The new batch of concrete containing returned freshconcrete shall meet all requirements of the purchaser.NOTE 2The requirements of this specification are in addition to thoseof the pur
13、chaser and the specification of the new batch of concretecontaining returned fresh concrete.1This specification is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC09.40 on Ready-Mixed Concrete.Current edition approved M
14、arch 15, 2016. Published April 2016. DOI: 10.1520/C1798_C1798M16E01.2See Section 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 serviceas
15、tm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1NOTE 3If using Specification C94/C94M for concrete potentiall
16、yincorporating returned fresh concrete, it is recommended the purchaserselect Option A. In this option, the manufacturer has responsibility formaking necessary adjustments to mixture proportions to ensure the newconcrete batch containing returned fresh concrete will meet the require-ments of the pur
17、chaser.4.2 At the request of the purchaser, the manufacturer shallfurnish information on procedures used to reuse returned freshconcrete.5. Measuring Materials5.1 The amount of returned fresh concrete shall be deter-mined by mass or volume with equipment capable of measur-ing within an accuracy of 6
18、 450 kg 1000 lb or 6 0.2 m30.25yd3.5.2 If necessary to convert between the mass and volume ofreturned fresh concrete, it shall be permissible to use themeasured or design density of the returned fresh concrete.5.3 Water added to the returned fresh concrete after theoriginal loading of the returned f
19、resh concrete until loading ofthe new batch of concrete shall be measured to an accuracy of6 3 % of the amount added or 4 liters 1.0 gal, whichever isgreater.5.4 Admixtures added to the returned fresh concrete afterthe original loading of the returned fresh concrete until loadingof the new batch of
20、concrete, whether in liquid or powder form,shall be measured with an accuracy of 6 3 % of the totalamount added or plus or minus the amount required for 50 kg100 lb of hydraulic cement, whichever is greater.5.5 Temperature of the returned fresh concrete shall bemeasured within 15 minutes before load
21、ing the new batch ofconcrete. Temperature shall be measured in accordance withTest Method C1064/C1064M or with equipment capable ofmeasuring concrete temperature to within 6 1 C 2 F of thetemperature measured by using Test Method C1064/C1064M.6. Requirements for Use6.1 The following shall apply to r
22、eturned fresh concrete thatis reused in a new batch of concrete.6.1.1 Returned fresh concrete that has reached an age of 90minutes after the original loading or first mixing of the returnedfresh concrete shall be treated with hydration stabilizingadmixture. The hydration stabilizing admixture shall
23、be addedduring or after the original loading or first mixing of thereturned fresh concrete.NOTE 4In many situations, the use of hydration stabilizing admixturesis essential to managing the time of setting of the new batch ofconcrete.4,5,6The selection of hydration stabilizing admixture dose de-pends
24、 on factors including mixture proportions, concrete temperature,time of setting, and duration of time for stabilization of the concrete.6.1.2 The manufacturer of the concrete shall be responsiblefor determining the dose of hydration stabilizing admixture.6.1.3 If hydration stabilizing admixture is u
25、sed, the returnedfresh concrete shall be incorporated into a new batch ofconcrete at a time appropriate for the dose of hydrationstabilizing admixture, but in no case more than 8 hours afterthe original loading or first mixing of the returned freshconcrete.6.1.4 The temperature of returned fresh con
26、crete shall notexceed 38 C 100 F. It shall not be permissible to coolreturned fresh concrete that has exceeded 38 C 100 F. Thetemperature of the new concrete batch containing returnedfresh concrete shall comply with project specifications.6.1.5 The specified strength of the returned fresh concretesh
27、all be equal to or greater than that of the new batch ofconcrete.6.2 The volume of returned fresh concrete incorporated intoa new batch of concrete shall not exceed 50 % of the totalvolume of the new batch of concrete containing returned freshconcrete.6.3 The age and number of revolutions for the ne
28、w batch ofconcrete shall be measured from the loading of the new batch.6.4 For the new batch of concrete containing returned freshconcrete, the returned fresh concrete and any new materialadded shall be mixed for a sufficient number of revolutions atthe mixing speed designated by the manufacturer of
29、 the truckmixer to produce the uniformity of concrete required inSpecification C94/C94M.6.5 The proportions of materials added to create the newbatch of concrete shall be adjusted to take into account theproportions and temperature of the returned fresh concrete andto meet the requirements of the pu
30、rchaser.7. Report7.1 The manufacturer of the concrete shall indicate to thepurchaser with each batch of concrete containing returned freshconcrete, before unloading at the site, the amount of returnedfresh concrete in cubic meters cubic yards.7.2 Additional information for certification purposes asd
31、esignated by the purchaser and required by the job specifica-tions shall be furnished when requested; such information as:7.2.1 Time loaded or of first mixing of cement and aggre-gates for the returned fresh concrete,7.2.2 Information necessary to calculate the total mixingwater in the returned fres
32、h concrete in liters/m3gal/yd3, and7.2.3 Temperature of the returned fresh concrete within 15minutes before loading the new batch of concrete.NOTE 5If using Specification C94/C94M, these reporting require-ments are in addition to those in Specification C94/C94M. If the purchaserof the new batch requ
33、ires a report of the amount of individual materialsbatched, these amounts include the individual materials originally batchedor subsequently added to the returned fresh concrete.8. Keywords8.1 mixing; ready-mixed concrete; returned fresh concrete;testing4ACI Manual of Concrete Practice 2010, Part 1,
34、 ACI 212.3R-04 ChemicalAdmixtures for Concrete, American Concrete Institute, P.O. Box 9094, Farmingtonhills, MI 48333.5Attiogbe, E., and Farzam, H., “Extended Set Control of Concrete,” Proceedingsof the ASCE Conference on Advances in the Production and Utilization ofCement-Based Materials, 1992, pp.
35、 137-146.6Lobo, Colin, William F. Guthrie and Raghu Kacker, “A Study on the Reuse ofPlastic Concrete Using Extended Set-Retarding Admixtures,” Journal of Researchof the National Institute of Standards and Technology, Volume 100, Number 5,SeptemberOctober 1995, pp. 575-589.C1798/C1798M 1612ASTM Inter
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37、their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand shou
38、ld be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Stan
39、dards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 1613
