1、ACI 325.13R-06 became effective February 27, 2006.Copyright 2006, 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 reproductionor for use in any knowledge or retrieval system or device, unless permission in writingis obtained from the copyright proprietors.ACI Committee Reports, Guides, and Commentaries areintended for guidance in planning, designing, executing, andinspecting co
3、nstruction. 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 andall resp
4、onsibility 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, theyshall be
5、 restated in mandatory language for incorporation bythe Architect/Engineer.325.13R-1Concrete Overlays for Pavement RehabilitationReported by ACI Committee 325ACI 325.13R-06This report provides information on the use of concrete overlays forrehabilitation of both concrete (rigid) and asphalt (flexibl
6、e) pavements.Selection, design, and construction of both bonded and unbonded overlaysare discussed. The overlay categories reviewed include bonded concreteoverlays, unbonded concrete overlays, whitetopping overlays, and concreteoverlays bonded to asphalt (ultra-thin and thin whitetopping). Informati
7、onis also provided on selecting overlay alternatives. Significant portions ofthis document are based on a synthesis report prepared for the FederalHighway Administration (FHWA) by Applied Pavement Technology, Inc.,under contract number DTFH61-00-P-00507. The report, “PortlandCement Concrete Overlays
8、: State of the Technology Synthesis,” is availablefrom the FHWA as publication FHWA-IF-02-045.Keywords: bond; concrete; joint; overlay; pavement (concrete); rehabilitation;repair.CONTENTSChapter 1Introduction, p. 325.13R-21.1Background1.2Purpose of report1.3Definitions and notationChapter 2Concrete
9、overlay types and construction materials, p. 325.13R-42.1Introduction2.2Types of concrete overlays2.3Overlay materials2.4Interface materials2.5Incidental materials2.6Concrete production, construction, and quality-controlissuesChapter 3Selection of concrete overlay alternatives, p. 325.13R-113.1Intro
10、duction3.2Effectiveness of different types of concrete overlays3.3Selection processDavid J. Akers Ben Gompers David N. Richardson Imran M. SyedRichard O. Albright W. Charles Greer John W. Roberts Shiraz D. Tayabji*William L. Arent Jerry A. Holland Raymond S. Rollings Susan L. TigheJamshid M. Armagha
11、ni Mark K. Kaler Jack A. Scott Samuel TysonBob J. Banka Gary Mitchell Sanjaya P. Senadheera Suneel N. VanikarDonald L. Brogna Paul E. Mueller Kieran G. Sharp Steven M. WaalkesArchie F. Carter Jon I. Mullarky*Terry W. Sherman Don J. WadeVan T. Cost Kamran M. Nemati James M. Shilstone, Sr. W. James Wi
12、lde*Juan P. Covarrubias Kelly L. Nix Hak-Chul Shin Gergis WilliamMohamed N. Darwish Nigel Parkes Kurt D. SmithJames M. WillsonMartin Gendreau Thomas J. Pasko, Jr. Tim J. Smith Dan G. ZollingerNader Ghafoori Steven A. Ragan Anthony M. Sorcic*Members of the task group drafting this document.Chair of t
13、he task group drafting this document.Norbert J. Delatte*ChairDavid W. PittmanVice ChairNeeraj J. BuchSecretary325.13R-2 ACI COMMITTEE REPORTChapter 4Bonded concrete overlays, p. 325.13R-134.1Introduction4.2Design4.3ConstructionChapter 5Unbonded concrete overlays,p. 325.13R-185.1Introduction5.2Design
14、5.3Construction5.4PerformanceChapter 6Conventional whitetopping overlays, p. 325.13R-256.1Introduction6.2Design6.3Construction6.4PerformanceChapter 7Ultra-thin and thin whitetopping overlays, p. 325.13R-307.1Introduction7.2Design7.3Construction7.4PerformanceChapter 8References, p. 325.13R-358.1Refer
15、enced standards and reports8.2Cited referencesCHAPTER 1INTRODUCTION1.1BackgroundHydraulic cement concrete overlays are used as a rehabilita-tion technique for both existing concrete and asphaltpavements. Concrete overlays offer the potential forextended service life, increased structural capacity, r
16、educedmaintenance requirements, and lower life-cycle costs whencompared with hot-mix asphalt overlay alternatives.Concrete overlays have been used to rehabilitate existingconcrete pavements since 1913 and to rehabilitate existingasphalt pavements since 1918 (Hutchinson 1982). Beginningaround the mid
17、-1960s, many highway agencies began to searchfor alternative means of rehabilitating existing pavements, andthe use of concrete overlays increased significantly (McGhee1994). In the 1990s, there was an even higher increase in theuse of concrete overlays, spurred by improvements in concretepaving tec
18、hnology. For example, the use of zero-clearancepavers, fast-track paving concepts, and high-early-strengthconcrete mixtures greatly increased the ability of concreteoverlays to serve as a viable rehabilitation alternative.Parallel with the increased use of concrete overlays,significant research aime
19、d at advancing the state of theknowledge of concrete overlays was conducted. One impetusfor this research was the Intermodal Surface TransportationAct (ISTEA) of 1991, which included a provision underSection 6005 allocating designated funding for the assessmentof thin bonded concrete overlays and su
20、rface laminationtechnology. The goals of the assessment were to evaluate thefeasibility, costs, and benefits of the techniques in minimizingoverlay thickness, initial laydown costs, and time out of service,and also to maximize life-cycle durability. As part of thiseffort, the Federal Highway Adminis
21、tration (FHWA)participated in funding 12 test-and-evaluation projectsthroughout the country (Sprinkel 2000).Other examples of ongoing studies of concrete overlaysare those being conducted under the FHWAs Long-TermPavement Performance (LTPP) program. The LTPPprogram is divided into two complementary
22、studies: theGeneral Pavement Studies (GPS) and the Specific PavementStudies (SPS). Under GPS-9, the performance of unbondedconcrete overlays is being investigated; currently, 14 projectsare being evaluated. Under SPS-7, the performance of fourbonded overlay projects is being studied. The long-termmo
23、nitoring of these GPS and SPS projects is expected toprovide valuable information on the design and constructionof concrete overlays. Additional information may beobtained by visiting the LTPP website at www.tfhrc.gov/pavement/ltpp/ltpp.htm.Resurfacing asphalt pavements with concrete overlays, aproc
24、ess known as whitetopping, is another example ofoverlay research. In particular, several studies on the use ofultra-thin whitetopping (UTW), a very thin (2 to 4 in. 50 to100 mm) layer of concrete bonded to an existing asphaltpavement, have been conducted. In the 1990s, this techniqueevolved from a r
25、adical rehabilitation concept to a mainstreamrehabilitation alternative. Several studies on whitetoppingoverlays are currently being conducted by the FHWA. Addi-tional information may be obtained at www.tfhrc.gov/pavement/utwweb/utw.htm.1.2Purpose of reportTwo ACI Committee 325 reports (ACI Committe
26、e 325 1958,1967) discussed the pioneering work by the U.S. ArmyCorps of Engineers to develop design procedures for concreteoverlays. The equations developed by the Corps for bonded,partially bonded, and unbonded concrete-on-concrete overlaysare still used. The report suggested the design of concrete
27、overlays on flexible pavement using the flexible pavement asa stiff base.During the 1980s and 1990s, two National CooperativeHighway Research Program (NCHRP) syntheses wereprepared on concrete overlays: “Resurfacing with PortlandCement Concrete” (Hutchinson 1982), and “Portland CementConcrete Resurf
28、acing” (McGhee 1994). There has been consid-erable work, however, in the area of concrete overlays sincethe most recent NCHRP synthesis.There is a need to assembleand synthesize information on the selection, design, andconstruction of concrete overlays for pavement rehabilitation.This report discuss
29、es the selection, design, construction,and performance of concrete overlays. It is intended toprovide the current state of the technology (as of 2004) ofconcrete overlays of both existing concrete pavements andexisting asphalt pavements.1.3Definitions and notation1.3.1 DefinitionsThis section presen
30、ts definitions andnotations unique to this report. Additional definitions forCONCRETE OVERLAYS FOR PAVEMENT REHABILITATION 325.13R-3common concrete terminology can be found in ACI 116R.Definitions shown in italics are terms that may be found inACI 116R, but have been redefined for this report.break
31、and seattechnique similar to crack and seat,except conducted on jointed reinforced concrete pavementsand using higher impact energy; uses more impact energy torupture the steel or break its bond with the concrete to ensureindependent movement, and seating with a heavy roller.crack and seattechnique
32、involving fracturing theexisting jointed plain concrete pavements into pieces 1 to 4 ft(0.3 to 1.2 m) on a side by inducing full-depth cracks usinga modified pile driver, guillotine hammer, whip hammer, orother equipment, and seating with a heavy roller.curlingconcrete distortion, usually in a slab,
33、 resultingfrom differential temperatures.drainage, subsurfaceinclusion of specific drainageelements in a pavement structure intended to remove excesssurface infiltration water from a pavement.equivalent single-axle loads (ESALs)summation of18 kip (80 kN) single-axle load applications used to combine
34、mixed traffic to design traffic during the analysis period.falling weight deflectometerdevice in which electronicsensors measure the deflection of the pavement as a result ofan impact load of known magnitude; results can be used toestimate the elastic moduli of subgrade and pavement layersand the lo
35、ad transfer across joints and cracks.faultingdifference of elevation across a joint.fracturing, slabtechnique in which an existing port-land-cement concrete pavement is cracked or broken intosmaller pieces to reduce the likelihood of reflection cracking.hot-mix asphalt (HMA)an asphalt cement-aggrega
36、temixture that is mixed, spread, and compacted at an elevatedtemperature; also commonly referred to as “asphaltconcrete” or “asphalt.”joint orientationalignment of transverse joints in a concretepavement with respect to the centerline of the pavement.layer, separatorlayer of hot-mix asphalt, bitumin
37、ousmaterial, or other stress-relieving material used at theinterface between an unbonded concrete overlay and theexisting concrete pavement to ensure independent behavior.leveling coursethin layer of hot-mix asphalt or otherbituminous material to produce a uniform surface for paving.load transfermea
38、ns through which wheel loads aretransferred or transmitted across a joint from one slab to the next.life-cycle cost analysis (LCCA)economic assessmentof competing pavement design alternatives in which allsignificant costs over the life of each alternative are considered.LCCA is used to evaluate a de
39、sign solution. Life-cycle costsmay be measured for different designs to determine whichdesign will meet the economic and performance goals.millprocess using drum-mounted carbide steel cuttingbits to remove material from a pavement and provide textureto promote bonding with an overlay.overlay, bonded
40、 concretehydraulic cement concreteoverlay bonded directly to an existing concrete pavement toform a monolithic structure.overlay, partially bondedhydraulic cement concreteoverlay that is placed directly on an existing portland-cementconcrete pavement with little or no surface preparation;consequentl
41、y, partial bonding between the two pavements isexpected.overlay, unbonded concretehydraulic cement concreteoverlay placed on an existing distressed concrete pavementsuch that the overlay is separated from the existing pavementthrough a separator layer.pavement, continuously reinforced concrete (CRCP
42、)pavement with uninterrupted longitudinal steel reinforcementand no intermediate transverse expansion or contraction joints.pavement, jointed plain concrete (JPCP)hydrauliccement concrete pavement system characterized by shortjoint spacings and no distributed reinforcing steel in the slab,with or wi
43、thout dowels.pavement, jointed reinforced concrete (JRCP)hydraulic cement concrete pavement system containingdowels, characterized by long joint spacings and distributedreinforcing steel in the slab to control crack widths.repair, preoverlayrepair or renovation activityperformed on an existing pavem
44、ent before the placement ofan overlay.roughnessirregularities in the pavement surface thatadversely affect ride quality, safety, and vehicle maintenancecosts.rubblize, rubblizationbreaking the existing pavementinto pieces no larger than 6 in. (150 mm) on a side using avibratory beam breaker or reson
45、ant frequency pavementbreaker.shotblastingsurface preparation technique in whichsteel shots are propelled against the surface of a portland-cement concrete pavement, effectively cleaning and preparingthe surface to receive a bonded concrete overlay.slab, shatteredconcrete pavement with extensivelong
46、itudinal and transverse cracking.slab, widenedconcrete pavement slab that is pavedwider (usually at least 18 in. 450 mm wider) than aconventional 12 ft (3.7 m) traffic lane to increase thedistance between truck tires and slab edge, thereby reducingedge stresses due to loading.strippingseparation of
47、asphalt cement from aggregatedue to moisture attack.user costsin a life-cycle cost analysis, costs incurred bythe user, such as delay costs, vehicle operating costs, andaccident costs.variable joint spacingseries of different joint spacingsrepeated in a regular pattern intended to reduce the rhythmi
48、cresponse of vehicles traveling over uniformly spaced joints.warpingconcrete distortion caused by differential moisture.whitetoppingconcrete overlay placed on an existingasphalt pavement. Whitetopping may be used in referring toconventional whitetopping, thin whitetopping, or ultra-thinwhitetopping.
49、whitetopping, conventionaloverlay placed on asphaltpavement, typically with a thickness higher than 8 in. (200 mm).whitetopping, thinbonded concrete overlay of thicknessbetween 4 and 8 in. (100 and 200 mm) and typically havinga joint spacing between 6 and 12 ft (1.8 and 3.7 m) that isplaced on milled asphalt pavement.325.13R-4 ACI COMMITTEE REPORTwhitetopping, utltra-thin (UTW)bonded concreteoverlay of thickness less than 4 in. (100 mm) and typicallyhaving a joint spacing less than 6 ft (1.8 m) that is placed
