1、Designation: C1798 16Standard Specification forReturned Fresh Concrete for Use in a New Batch of Ready-Mixed Concrete1This standard is issued under the fixed designation C1798; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye
2、ar of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers returned fresh concrete for usein a new batch of ready-mixed concrete. Requirements fo
3、rreturned 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 thisspecification, the purchasers requirements shall govern. Thisspecification does not cover the placement, consolidation,curing
4、, 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 new batchof concrete.NOTE 1The permission to use returned fresh concrete may beaddressed in purchase documents, which may
5、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 stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not
6、 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 text of this standard references notes and footnotes,which provide explanatory information. These notes and foot-notes sha
7、ll 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 theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility o
8、f regulatory limitations prior to use. (WarningFreshhydraulic cementitious mixtures are caustic and may causechemical burns to skin and tissue upon prolonged use.2)2. Referenced Documents2.1 ASTM Standards:3C94/C94M Specification for Ready-Mixed ConcreteC125 Terminology Relating to Concrete and Conc
9、rete Ag-gregatesC494/C494M Specification for Chemical Admixtures forConcreteC1064/C1064M Test Method for Temperature of FreshlyMixed Hydraulic-Cement Concrete3. Terminology3.1 DefinitionsThe terms used in this specification aredefined in Terminology C125.3.2 Definitions of Terms Specific to This Sta
10、ndard:3.2.1 admixture, hydration stabilizing, nset-retardingadmixture, conforming to Specification C494/C494M Type Bor D, that can predictably reduce the hydration rate of cementfor applications requiring the management of time of setting ofreturned concrete, reducing the hydration rate of cement fi
11、nesin water from concrete production, or for applications requiringextended delivery time of ready-mixed concrete.3.2.2 concrete, returned fresh, nfresh concrete not yetdischarged from a ready-mixed concrete transportation unitwhen it is returned to the manufacturer.4. Ordering Information4.1 The ne
12、w 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 purchaser and the specification of the new batch of concretecontaining returned fresh concrete.NOTE 3If using Specification C
13、94/C94M for concrete potentiallyincorporating 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 me
14、et the require-ments of the purchaser.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 March 15, 2016. Published April 2016. DOI: 10.1520/C179
15、816.2See 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 serviceastm.org. For Annual Book of ASTMStandards volume information, ref
16、er 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 States14.2 At the request of the purchaser, the manufacturer shallfurnish information on procedures used to reuse returned freshconc
17、rete.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 6 450 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 pe
18、rmissible 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 fresh 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
19、 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 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
20、 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 loading the new batch ofconcrete. Temperature shall be measured in accordance withTest Method C1064/C1064M or with equipment capable ofm
21、easuring 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 returned fresh concrete thatis reused in a new batch of concrete.6.1.1 Returned fresh concrete that has reached an age of 90minutes a
22、fter the original loading or first mixing of the returnedfresh concrete shall be treated with hydration stabilizingadmixture. The hydration stabilizing admixture shall be addedduring or after the original loading or first mixing of thereturned fresh concrete.NOTE 4In many situations, the use of hydr
23、ation 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 on factors including mixture proportions, concrete temperature,time of setting, and duration of time for stabilization of the concr
24、ete.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 used, the returnedfresh concrete shall be incorporated into a new batch ofconcrete at a time appropriate for the dose of hydrationsta
25、bilizing 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 concrete shall notexceed 38 C 100 F. It shall not be permissible to coolreturned fresh concrete that has exceeded 38 C 100 F. Thetemper
26、ature of the new concrete batch containing returnedfresh concrete shall comply with project specifications.6.1.5 The specified strength of the returned fresh concreteshall be equal to or greater than that of the new batch ofconcrete.6.2 The volume of returned fresh concrete incorporated intoa new ba
27、tch 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 new batch ofconcrete shall be measured from the loading of the new batch.6.4 For the new batch of concrete containing returned freshco
28、ncrete, 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 the truckmixer to produce the uniformity of concrete required inSpecification C94/C94M.6.5 The proportions of materials added to cr
29、eate 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 purchaser.7. Report7.1 The manufacturer of the concrete shall indicate to thepurchaser with each batch of concrete containing returned
30、 freshconcrete, before unloading at the site, the amount of returnedfresh concrete in cubic meters cubic yards.7.2 Additional information for certification purposes asdesignated by the purchaser and required by the job specifica-tions shall be furnished when requested; such information as:7.2.1 Time
31、 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 fresh concrete in liters/m3gal/yd3, and7.2.3 Temperature of the returned fresh concrete within 15minutes before loading the new batch of
32、 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 requires a report of the amount of individual materialsbatched, these amounts include the individual materials originally batchedor subs
33、equently added to the returned fresh concrete.8. Keywords8.1 mixing; ready-mixed concrete; returned fresh concrete;testing4ACI Manual of Concrete Practice 2010, Part 1, ACI 212.3R-04 ChemicalAdmixtures for Concrete, American Concrete Institute, P.O. Box 9094, Farmingtonhills, MI 48333.5Attiogbe, E.,
34、 and Farzam, H., “Extended Set Control of Concrete,” Proceedingsof the ASCE Conference on Advances in the Production and Utilization ofCement-Based Materials, 1992, pp. 137-146.6Lobo, Colin, William F. Guthrie and Raghu Kacker, “A Study on the Reuse ofPlastic Concrete Using Extended Set-Retarding Ad
35、mixtures,” Journal of Researchof the National Institute of Standards and Technology, Volume 100, Number 5,SeptemberOctober 1995, pp. 575-589.C1798 162ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. User
36、s of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every
37、five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technica
38、l 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 Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken,
39、 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:/ 163
