ACI 309 5R-2000 Compaction of Roller-Compacted Concrete《碾压混凝土的压实》.pdf

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1、ACI 309.5R-00 became effective February 23, 2000.Copyright 2000, American Concrete Institute.All rights reserved including rights of reproduction and use in any form or by anymeans, including the making of copies by any photo process, or by electronic ormechanical device, printed, written, or oral,

2、or recording for sound or visual reproduc-tion or for use in any knowledge or retrieval system or device, unless permission inwriting is obtained from the copyright proprietors.309.5R-1ACI Committee Reports, Guides, and Commentaries areintended for guidance in planning, designing, executing, andinsp

3、ecting construction. This document is intended for the useof individuals who are competent to evaluate the significanceand limitations of its content and recommendations and whowill accept responsibility for the application of the material itcontains. The American Concrete Institute disclaims any an

4、dall responsibility for the stated principles. The Institute shallnot be liable for any loss or damage arising therefrom.Reference to this document shall not be made in contractdocuments. If items found in this document are desired by theArchitect/Engineer to be a part of the contract documents, the

5、yshall be restated in mandatory language for incorporation bythe Architect/Engineer.Compaction of Roller-Compacted ConcreteACI 309.5R-00(Reapproved 2006)Roller-compacted concrete (RCC) is an accepted and economical methodfor the construction of dams and pavements. Achieving adequate compac-tion is e

6、ssential in the development of the desired properties in the hard-ened material. The compaction depends on many variables, including thematerials used, mixture proportions, mixing and transporting methods, dis-charge and spreading practices, compaction equipment and procedures,and lift thickness. Th

7、e best performance characteristics are obtained whenthe concrete is reasonably free of segregation, well-bonded at constructionjoints, and compacted at, or close to, maximum density.Compaction equipment and procedures should be appropriate for thework. In dam or massive concrete applications, large,

8、 self-propelled,smooth, steel-drum vibratory rollers are used most commonly. The frequencyand amplitude of the roller should be suited to the mixture and lift thicknessrequired for the work. Other roller parameters, such as static mass, numberof drums, diameter, ratio of frame and drum mass, speed,

9、and drum driveinfluence the rate and effectiveness of the compaction equipment. Smallerequipment, and possibly thinner compacted lifts, are required for areaswhere access is limited.Pavements are generally placed with paving machines that produce asmooth surface and some initial compacted density. F

10、inal density is obtainedwith vibratory rollers. Rubber-tired rollers can also be used where surfacetearing and cracks would occur from steel-drum rolling. The rubber-tiredrollers close fissures and tighten the surface.Inspection during placement and compaction is also essential to ensurethe concrete

11、 is free of segregation before compaction and receives adequatecoverage by the compaction equipment. Testing is then performed on thecompacted concrete on a regular basis to confirm that satisfactory densityis consistently achieved. Corrective action should be taken whenever unsat-isfactory results

12、are obtained. RCC offers a rapid and economical methodof construction where compaction practices and equipment are a majorconsideration in both design and construction.Keywords: compaction; consolidation; dams; pavements; roller-compacted concrete.CONTENTSChapter 1Introduction, p. 309.5R-21.1General

13、1.2Scope and objective1.3Description1.4Terminology1.5Importance of compactionChapter 2Mixture proportions, p. 309.5R-32.1General2.2Moisture-density relationship2.3Coarse aggregateChapter 3Effects on properties, p. 309.5R-43.1General3.2Strength3.3Watertightness3.4DurabilityChapter 4Equipment, p. 309.

14、5R-64.1General4.2Vibratory rollers4.3Rubber-tired rollers4.4Small compactors4.5Paving machinesReported by ACI Committee 309Richard E. Miller, Jr.ChairmanNeil A. Cumming Glen A. Heimbruch Celik H. OzyildirimTimothy P. Dolen Kenneth C. Hover Steven A. RaganChiara F. Ferraris Gary R. Mass Donald L. Sch

15、legelJerome H. Ford Bryant Mather Mike ThompsonSteven H. Gebler Larry D. Olson Brad K. Voiletta309.5R-2 ACI COMMITTEE REPORTChapter 5Placement and compaction, p. 309.5R-85.1General5.2Minimizing segregation5.3Placement and compaction in dams and related work5.4Placement and compaction of pavementsCha

16、pter 6Construction control, p. 309.5R-116.1General6.2Consistency and moisture content6.3In-place density6.4Maximum density6.5Strength6.6Inspection of compaction operationsChapter 7References, p. 309.5R-137.1Referenced standards and reports7.2Cited referencesCHAPTER 1INTRODUCTION1.1GeneralRoller-comp

17、acted concrete (RCC) has become an acceptedmaterial for constructing dams and pavements, rehabilitatingand modifying existing concrete dams, and providing over-flow protection of embankment dams and spillways. Its pro-duction provides a rapid method of concrete constructionsimilar in principle to so

18、il-cement and other earthwork con-struction. RCC technology developed considerably in the1980s, after early research by Cannon (1972), Dunstan (1977),Hall and Houghton (1974), and the development of the roll-er-compacted dam (RCD) method in Japan in the 1970s. Also,in the 1980s, RCC was developed as

19、 a heavy-duty paving ma-terial for log sorting yards, tank hardstands, railroad sortingyards, and other industrial pavements. It also found applicationin roadways and parking areas. Detailed information on theuse of RCC in mass concrete and paving applications is con-tained in ACI 207.5R and ACI 325

20、.10R, respectively.1.2Scope and objectiveThis report presents a discussion of the equipment and spe-cial construction procedures associated with the compactionof RCC. It includes characteristics of the mixture relevant tocompaction and the effects of compaction on desired proper-ties of RCC. These p

21、roperties include various strength param-eters, watertightness, and durability. Differentiation is madebetween RCC used in massive concrete work and that usedin pavements. The discussion also includes provisions formeasurement of compaction. This report does not coversoil-cement or cement-treated ba

22、se.The objective of this report is to summarize experience incompaction of RCC in various applications, to offer guid-ance in the selection of equipment and procedures for com-paction, and in quality control of the work.1.3DescriptionAccording to ACI 116R, roller-compacted concrete is de-fined as “c

23、oncrete compacted by roller compaction that, inits unhardened state, will support a roller while being com-pacted.” ACI 116 further defines roller compaction as “aprocess for compacting concrete using a roller, often a vi-brating roller.”RCC construction involves placement of a no-slump con-crete mi

24、xture in horizontal lifts ranging from 150 to 600 mm(0.5 to 2 ft) thick and compaction of this mixture, normallywith a smooth-drum, vibratory roller. For RCC dams, multi-ple lifts of concrete, generally 300 mm (1 ft) thick, are con-tinuously placed and compacted to construct a cross sectionthat is s

25、imilar to a conventional concrete gravity dam. AnotherRCC placing method is to spread three or more thinner (typi-cally approximately 230 mm 9 in.) layers with a bull-dozerbefore compacting them into one thick lift with a vibratory roll-er. One significant difference between an RCC dam and aconventi

26、onal concrete dam is the continuous placing of ahorizontal lift of concrete from one abutment to the other,rather than constructing the dam in a series of separate mono-liths. A horizontal construction joint is produced betweeneach lift in the RCC dam. In paving applications, individuallanes of conc

27、rete are placed adjacent to each other to con-struct a pavement ranging from 150 to 250 mm (6 to 10 in.)thick. The procedure is similar to asphalt-paving techniques.In some instances, two or more lifts of RCC are quicklyplaced and compacted to construct a thicker, monolithicpavement section for heav

28、y-duty use.Several steps are required to achieve proper compactionof RCC construction: 1) A trial mixture should be developedusing appropriate testing methods to determine the optimumconsistency and density for each application; 2) A trial sec-tion should be constructed to validate the number of pas

29、sesand establish the required moisture content and density; 3)The RCC should be placed on freshly compacted material,or, if the surface is not freshly compacted or is the start of anew lift, place a more workable mixture, or place over abond layer of mortar; 4) For dams, roll from one abutmentto the

30、 other continuously; 5) For pavements, roll immediate-ly behind the paver and place the next lift within 1 h; 6) Rollthe proper number of passes before placing the next lift; 7)Use a tamper or small compactor along edges where a rollercannot operate; and 8) Maintain a site quality-control pro-gram.

31、The details of proper compaction and the ramifica-tions of improper compaction are provided in the followingchapters.1.4TerminologyThe terms compaction and consolidation have both beenused to describe the densification process of freshly mixedconcrete or mortar. In ACI 309R, consolidation is the pre

32、-ferred term used for conventional concrete work. For the pur-poses of this document on roller-compacted concrete,however, the term compaction will be used for all types ofRCC mixtures, because it more appropriately describes themethod of densification.1.5Importance of compactionThe effect of compac

33、tion on the quality of RCC is signifi-cant. Higher density relates directly to higher strength, lowerpermeability, and other important properties. RCC mixturesare generally proportioned near the minimum paste content309.5R-3COMPACTION OF ROLLER-COMPACTED CONCRETEto fill voids in the aggregate, or at

34、 a water content that pro-duces the maximum density when a compactive effortequivalent to the modified Proctor procedure (ASTM D1557) is applied. The use of RCC in either massive struc-tures or pavement construction needs to address the compac-tion of each lift because of its influence on performanc

35、e.Failure to compact the concrete properly can cause potentialseepage paths and reduce the stability in RCC dams or re-duce the service life of RCC pavements.In the 1980s, core sampling from RCC dams revealedinstances of voids and low density in the lower one-third oflifts of RCC that had been place

36、d and compacted in 300 mm(1 ft) lifts (Drahushak-Crow and Dolen 1988). Lower densityat the bottom of lifts can be attributed to lack of compactiveeffort but is more commonly due to segregation of the mix-ture during the construction process. This segregation causesexcessive voids in the RCC placed j

37、ust above the previouslycompacted lift. Segregation is a major concern in dams dueto the potential seepage path and the potential for a continu-ous lift of poorly bonded RCC from one abutment to the otherthat could affect the sliding stability. RCC dams constructedin earthquake zones can also requir

38、e tensile strength acrossthe horizontal joints to resist seismic loading. At WillowCreek Dam, seepage through a nonwatertight upstream face,and segregation at lift lines required remedial grouting (U.S.Army Corps 1984). This RCC dam was considered safe,from a sliding stability standpoint, due to its

39、 conservativedownstream slope of 0.8 horizontal to 1.0 vertical. Recent in-novations in South Africa (Hollingworth and Geringer 1992)and China have included the construction of RCC arch-grav-ity dams with very steep downstream slopes where bondingacross lift joints is critical to the stability of th

40、ese structures.In pavements, flexural strength is dependent on thoroughcompaction at the bottom of the pavement section, whiledurability is dependent on the same degree of compaction atthe exposed surface. Furthermore, construction joints betweenpaving lanes are locations of weakness and are particu

41、larlysusceptible to deterioration caused by freezing and thawingunless good compaction is achieved.CHAPTER 2MIXTURE PROPORTIONS2.1GeneralRCC mixtures should be proportioned to produce concretethat will readily and uniformly compact into a dense materialwith the intended properties when placed at a r

42、easonable liftthickness. Procedures for proportioning RCC mixtures areprovided in ACI 211.3R, ACI 207.5R, and ACI 325.10R.The ability to compact RCC effectively is governed by themixture proportioning as follows: Free-water content; Cement plus pozzolan content and cement: pozzolan ratio; Sand conte

43、nt, grading, and amount of nonplastic fines (if used); Nominal maximum size of aggregate; Air-entraining admixtures (if used); and Other admixtures (water-reducing, retarding or both).For a given ratio of cement plus pozzolan, sand, fines(passing the 75m No. 200) sieve, and coarse aggregate,the work

44、ability and ability to compact RCC effectively willbe governed by the free-water content. As the water contentincreases from the optimum level, the workability increasesuntil the mixture will no longer support the mass of a vibrat-ing roller. As the water content decreases from the optimumlevel, suf

45、ficient paste is no longer available to fill voids andlubricate the particles, and compacted density is reduced.RCC mixtures have no measurable slump, and the con-sistency is usually measured by Vebe consistency time inaccordance with ASTM C 1170. The Vebe time is mea-sured as the time required for

46、a given mass of concrete to beconsolidated in a cylindrically shaped mold. A Vebe time of5 seconds (s) is similar to zero-slump concrete (no-slumpconcrete), and at such consistency, it is difficult to operate aroller on the surface without weaving, pumping, and sinking.For RCC mixtures used in dam w

47、ork, a Vebe time of approx-imately 15 s is suitable for compaction in four to six passeswith a dual-drum, 9 tonne (10 ton) vibratory roller. A normalrange would be 15 to 20 s. At Victoria Dam Rehabilitation, theVebe consistency of RCC ranged from approximately 15 to20 s in the laboratory. In the fie

48、ld, the water content of theRCC was decreased and the Vebe consistency increased toapproximately 35 to 45 s (Reynolds, Joyet, and Curtis 1993).The Vebe consistency test was not as reliable an indicator ofworkability at these consistency levels. Compaction wasachieved by up to eight passes with a 9 t

49、onne (10 ton) dual-drum vibratory roller at this consistency. RCC mixtures with ahigh consistency time, up to 180 s, have been compacted in thelaboratory. RCC of this consistency required two to three timesmore compactive effort to achieve the equivalent percent com-paction than mixtures with a lower consistency (Casias, Gold-smith, and Benavidez 1988). A Vebe time of 30 to 40 s appearsto be more appropriate for RCC pavement and overtoppingprotection mixtures.Lean RCC mixtures can benefit from the addition of non-plastic fines (material