1、ACI 223R-10Reported by ACI Committee 223Guide for the Use ofShrinkage-Compensating ConcreteGuide for the Use of Shrinkage-Compensating ConcreteFirst PrintingDecember 2010ISBN 978-0-87031-404-9American Concrete InstituteAdvancing concrete knowledgeCopyright by the American Concrete Institute, Farming
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15、corporation bythe Architect/Engineer.Guide for the Use ofShrinkage-Compensating ConcreteReported by ACI Committee 223ACI 223R-10Shrinkage-compensating concrete is used in construction to minimize drying-shrinkage cracking. Its characteristics are similar to those of portland-cementconcrete. The mate
16、rials, proportions, placement, and curing should ensurethat expansion compensates for subsequent drying shrinkage.This guide sets forth criteria and practices to ensure the development ofexpansive strain in concrete. In addition to a discussion of basic principles,methods and details are given cover
17、ing structural design, concrete mixtureproportioning, placement, finishing, and curing.The materials, processes, quality control measures, and inspectionsdescribed in this document should be tested, monitored, or performed asapplicable only by individuals holding the appropriate ACI Certificationsor
18、 equivalent.Keywords: cement, calcium; cement, expansion; concrete, shrinkage-compensating; cracking, shrinkage; mixture proportions; restraints; shrink-age, drying; slab-on-ground; structural design.CONTENTSChapter 1Introduction and scope, p. 21.1Introduction1.2ScopeChapter 2Notation and definition
19、s, p. 22.1Notation2.2DefinitionsChapter 3General considerations, p. 33.1Preconstruction meetingChapter 4Materials, p. 34.1Expansive cement and expansive component systems4.2Aggregates4.3Water4.4Admixtures4.5ConcreteChapter 5Structural design considerations, p. 55.1General5.2Restraint5.3Reinforced st
20、ructural slabsBenoit Bissonnette Herbert G. Gelhardt III Kevin A. MacDonald Henry G. RussellDavid A. Crocker Robert J. Gulyas Jerry Parnes Caroline M. TalbotC. Rick Felder George C. Hoff Roy H. Reiterman James I. Turici Jr.Barry E. Foreman Jerry A. Holland Edward H. Rubin Lawrence J. ValentineTerry
21、J. Fricks Federico Lopez Flores Edward D. RussellJohn W. RohrerChairKarl J. BakkeSecretary2 GUIDE FOR THE USE OF SHRINKAGE-COMPENSATING CONCRETE (ACI 223R-10)American Concrete Institute Copyrighted Materialwww.concrete.org5.4Reinforced slabs-on-ground5.5Post-tensioned structural concrete5.6Post-tens
22、ioned slabs-on-ground5.7Walls5.8Toppings5.9FormworkChapter 6Concrete mixture proportioning, p. 136.1General6.2Concrete proportions6.3Admixtures6.4Consistency6.5Mixture proportioning proceduresChapter 7Placing, finishing, and curing, p. 147.1Placing7.2Finishing7.3CuringChapter 8References, p. 158.1Re
23、ferenced standards and reports8.2Cited referencesCHAPTER 1INTRODUCTION AND SCOPE1.1IntroductionShrinkage-compensating concrete is made with an expansivecement or expansive component system in which initialexpansion, if properly restrained, offsets strains caused bydrying shrinkage. Since the mid-196
24、0s, shrinkage-compensating concrete has been used in many applications.These applications include highway and airport pavements,bridge decks (Gruner and Plain 1993; Ramey et al. 1999),hydraulic structures, wastewater treatment plants, containmentstructures (Valentine 1994), post-tensioned structures
25、(Hoffman 1980; Eskildsen et al. 2009), parking structures, andslabs-on-ground (Keith et al. 1996, 2006; Bailey et al. 2001).Shrinkage-compensating concrete is used to minimizecracking and structural movement caused by drying shrinkagein concrete. Drying shrinkage is the contraction in theconcrete ca
26、used by moisture loss from drying concrete. Itdoes not include plastic volume changes that occur beforesetting when surface evaporation exceeds concrete bleedingrate or length and volume changes induced by temperature,structural loads, or chemical reactions.The amount of drying shrinkage that occurs
27、 in concretestructures depends on the constituent materials, mixtureproportions, curing, drying environment, and restraint.Tensile stresses caused by restraint to drying shrinkage canoccur before concrete tensile strength is fully developed.When concrete is restrained by reinforcement, subgradefrict
28、ion, or other means, drying shrinkage causes tensile stressesto develop. When drying shrinkage stresses exceed the tensilestrength of the concrete, it cracks. The spacing and size ofcracks that develop in structures depend on the amount ofshrinkage, degree of restraint, and amount of reinforcement.S
29、hrinkage-compensating concrete is proportioned soconcrete volume increases after setting and during early-agehardening. When restrained by reinforcement, concreteexpansion results in tension in reinforcement and compressionin concrete. Upon drying, the shrinkage, instead of causingtensile stress tha
30、t results in cracking, relieves compressivestresses caused by initial expansion of the shrinkage-compensating concrete.1.2ScopeRecommendations of this guide include proportioning,mixing, placing, finishing, curing, and testing. Shrinkage-compensating concrete is produced using expansive cementsor ex
31、pansive component systems.There have been significant changes and advances in theuse of shrinkage-compensating concrete since it was firstintroduced into the market but, in some areas, the originalpractices remain the best current practice. Although manyreferences used in this guide are over 10 year
32、s old, theyremain a valid reference to todays practice.CHAPTER 2NOTATION AND DEFINITIONS2.1Notationc = bar diameter/2 = db/2db= bar diameterE = modulus of elasticity of the barfy= stress in reinforcing barI = moment of inertia of barL =lengthl = total length of wall between free ends M = moment in r
33、einforcing barT = tolerance allowance = anticipated wall movement relative to footing = expansion of wall2.2DefinitionsACI provides a comprehensive list of definitions through anonline resource, “ACI Concrete Terminology,”http:/terminology.concrete.org. Definitions providedherein complement that res
34、ource.concrete, shrinkage-compensatinga concrete made withan expansive cement or component system in which theexpansion, if properly restrained, induces compressive stressesthat approximately offset tensile stresses caused by shrinkage.cement, expansivea cement that, when mixed withwater, produces a
35、 paste that, after setting, increases involume to a significantly greater degree than does portlandcement paste; used to compensate for volume decrease dueto shrinkage or to induce tensile stress in reinforcement.1. cement, expansive, Type Ka mixture of portlandcement, anhydrous tetracalcium trialum
36、inate sulfate(C4A3S), calcium sulfate (CaSO4), and lime (CaO); theC4A3S is a constituent of a separately burned clinkerthat is interground with portland cement or alternately,it may be formed simultaneously with the portland-cement clinker compounds during the burning process.2. cement, expansive, T
37、ype Minterground or blendedmixtures of portland cement, calcium-aluminatecement, and calcium sulfate suitably proportioned.3. cement, expansive, Type Sa portland cementcontaining a high computed tricalcium aluminateGUIDE FOR THE USE OF SHRINKAGE-COMPENSATING CONCRETE (ACI 223R-10) 3American Concrete
38、 Institute Copyrighted Materialwww.concrete.org(C3A) content and an amount of calcium sulfate abovethe usual amount found in portland cement.expansive component system (general)a combinationof portland cement and expansive component that whenmixed with water forms a paste that, after setting, increa
39、sesin volume to a significantly greater degree than portlandcement paste.1. expansive component Type Ka blend of calciumsulfoaluminate and calcium sulfate that producesettringite when mixed with portland cement and water.2. expansive component Type Ma blend of calcium-aluminate cement and calcium su
40、lfate that producesettringite when mixed with portland cement and water.3. expansive component Type Sa blend of tricalciumaluminate (C3A) cement and calcium sulfate thatproduces ettringite when mixed with portland cementand water.4. expansive component Type Ga blend of calciumdioxide and aluminum di
41、oxide that produces calciumhydroxide platelet crystals when mixed with portlandcement and water.CHAPTER 3GENERAL CONSIDERATIONSDrying shrinkage of concrete is affected mainly by watercontent, aggregate composition and size, drying environ-ment, mixture proportions, and paste content. Lower watercont
42、ent, aggregate with a higher modulus of elasticity, largeraggregate size, longer moist curing, and leaner mixturesreduce drying shrinkage.Concrete drying shrinkage typically ranges from 0.03% to0.06%. Drying shrinkage of a concrete mixture is determinedby using ASTM C157/C157M. ASTM C157/C157Mlabora
43、tory tests give results that are typically higher than theshrinkage of concrete placed in the field.Beyond the shrinkage-compensating component, thematerials used to produce shrinkage-compensating concreteare the same as those required to produce portland-cementconcrete. Shrinkage-compensating concr
44、etes ability tominimize cracking depends on water curing for 7 days. It isessential that water curing and protection of the concrete isprovided as discussed in ACI 301 or ACI 308.1. Mixtureproportions should ensure initial expansion to offset subsequentdrying shrinkage. Physical characteristics and
45、durability ofcured shrinkage-compensating concrete are similar to thoseof portland-cement concrete.3.1Preconstruction meetingThe owners representative, in cooperation with the designerand general contractor, should conduct a preconstructionmeeting after all mixture designs are approved. This shouldo
46、ccur at least 1 week before the first placement of concrete.Parties review, discuss, and agree to procedures for placing,finishing, and curing the concrete to meet specifications underanticipated field conditions. Responsible representatives of allcontractors and material suppliers, including the ma
47、nufacturerof the shrinkage-compensating cement or component, theready mixed concrete producer, and concrete testing laboratoryshould participate in this meeting.Be aware that additional time for testing may be necessarywhen using an expansive component to produce shrinkage-compensating concrete. Pro
48、portions may need to be adjustedor material sources changed during the testing process toachieve the strength and expansive properties specified.CHAPTER 4MATERIALS4.1Expansive cement and expansive component systemsThe expansion characteristics of expansive cements andexpansive component systems are
49、determined by theconstituents that create the expansion mechanisms (refer toTable 4.1). Expansion produced by each system is determinedby the ASTM C806 test method. This test measures theexpansive potential of the cementitious materials and componentsystems and is used to evaluate performance compared withexpansion requirements of mortar in ASTM C845.When using ASTM C806 with a component system, thetest amount of cement required in the mortar should consistof the portland cement and component in the same proportionsthat will b
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