ASTM C1761 C1761M-2015 Standard Specification for Lightweight Aggregate for Internal Curing of Concrete《混凝土内部固化用轻骨料的标准规格》.pdf
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1、Designation: C1761/C1761M 15Standard 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.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 Aggregatesfor ConcreteC87 Test Method for Effect of Organic Impurities in FineAggregate on Strength of Mortar
9、C114 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 Test Method for Sieve Analysis of Fine and CoarseAggregatesC142 Test Method for Clay Lu
10、mps and Friable Particles inAggregatesC330/C330M Specification for Lightweight Aggregates forStructural ConcreteC641 Test Method for Iron Staining Materials in Light-weight Concrete AggregatesC702 Practice for Reducing Samples ofAggregate to TestingSizeC1498 Test Method for Hygroscopic Sorption Isot
11、herms ofBuilding MaterialsC1608 Test Method for Chemical Shrinkage of HydraulicCement PasteC1698 Test Method for Autogenous Strain of Cement Pasteand MortarD75 Practice for Sampling AggregatesE11 Specification for Woven Wire Test Sieve Cloth and TestSieves3. Terminology3.1 Definitions:3.1.1 For defi
12、nitions of terms used in this practice, refer toTerminology C125.3.2 Definitions of Terms Specific to This Standard:3.2.1 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
13、after being submerged for 72 h, expressed 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.1This specifica
14、tion is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC09.21 on Lightweight Aggregates and Concrete.Current edition approved April 1, 2015. Published May 2015. Originallyapproved in 2012. Last previous edition approved
15、 in 2013 as C1761/C1761M 13b.DOI: 10.1520/C1761_C1761M-15.2For referenced ASTM standards, visit the ASTM website, 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
16、Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.2.1 DiscussionThe chemical shrinkage leads to emp-tying of the internal pores (see self-desiccation) that causes theform
17、ation 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 shrinkage isless than the chemical shrinkage after setting occurs, because
18、the 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 hydration because thehydration products occupy less volume than the volumeoccupied
19、 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 the permeableand impermeable pores within the particles but does notinclud
20、e 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 attains moisture equilibrium with the surroundingenvironment maintained at co
21、nstant 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 othermaterials that readily release water from within the particles,thereby
22、 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 5C230 6 10 F for sufficient time to reach a constant mass.3.2.8 relative
23、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, the condition in which the permeablepores of lightweight aggregate particle
24、s 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 mixture, due to chemicalshrinkage, that may reduce the rate of hydration
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