Maintenance, Repair & Rehabilitation of Concrete Bridges—Winter ...

MAINTENANCE, REPAIR,and REHABILITATIONOF CONCRETEBRIDGESTo perform efficient and cost-effectiverepairs on bridge abutments, theOhio Department of Transportationplaces activated-zinc anode strips(in red) parallel to epoxy-coatedreinforcement (green) after thedelaminated concrete is removed.The anodes provide global protectionfor the abutment reinforcement andextend the abutments’ service life.The project shown is the KirkwoodBridge in Sydney, Ohio.Minimizing Repair Impactby Craig A. ShuttRepairing deteriorating bridges withoutcausing considerable impact to userscreates a difficult balancing act. TheOhio Department of Transportationhas found a solution for its abutmentrepairs by using activated-zinc anodestrips distributed throughout a newreinforced concrete facing. Comparedto previous repair methods, thegalvanic encasement combinationextends the bridge’s service life andprovides global protection to theabutment in a quick and economicalway rather than protection only to thepatched area.The department’s designs for castin-placeconcrete, continuous, slabbridges typically have a constructionjoint located over the abutment. Thisexposes the abutment to chloridepenetration from deicing salts andsubsequent corrosion of the abutmentreinforcement. Typically, the slabsremain in good condition, withonly the abutment under the jointdeteriorating.Previously, to repair the damage,temporary shoring would be placedunder the slab and the abutmentswould be replaced. This required eithercomplete bridge closure or phasedconstruction. Both of these createdtraffic delays and disruptions. But theother options of doing nothing orreplacing the bridge were not feasibleeither for safety or economic reasons.Ohio began using discrete activated-zincanodes several years ago, first as a localizedrepair. The puck-sized anode units, suppliedby Vector Corrosion Technologies, Tampa,Fla., attach to the exposed reinforcementusing integral tie wires, and consist of azinc core surrounded by a highly alkalinecementitious matrix. The zinc has a highercorrosion potential than the reinforcingsteel, allowing the anode to corrode ratherthan the steel.Providing this galvanic protection allowedisolated patch repairs to be accomplishedquickly, with minimal impact on trafficand at a low cost. However, the localizedbenefit provided by the discrete zincanodes assured protection only aroundthe patch to mitigate the “halo” effect.This effect involves the area aroundthe patch that begins to corrode at anaccelerated rate.To provide extra protection for theentire abutment face, the departmenthas completed several projects thatnow supply global protection throughthe use of activated distributed zinc“strip” anodes. In this process, thedelaminated concrete is removed, andthe new reinforcing steel is installedalong the face of the exposed concrete.Zinc anode strips are placed parallelASPIRE, Winter 2009 | 41

with the epoxy-coated reinforcement and are connected backto the reinforcing steel in the existing abutment. Then amonolithic concrete placement encases the anodes and fills inthe repaired areas.This solution has been used for several years and offersseveral advantages, including the short time required forthis comprehensive repair and future protection. Monitoredlocations indicate that the anode strips will provide over 20years of protection, but this can be adjusted by changing theamount of zinc provided or the anode spacing.This approach also provides an inexpensive repair method. Atthe time of repair of the Kirkwood Bridge, located near Sidney,Ohio, rehabilitating the abutment with anode strips costapproximately $319,000. To replace the abutment and providetemporary shoring cost about $427,000, while replacing theentire structure cost about $4.5 million.The program has worked so well that it has been extended toother concrete structures. The anode strips have been used ineight bridge deck overlays in a Lake County, Ohio, project, aswell as to protect columns with reinforced concrete jackets,pier-cap repairs, and pile protection in marine structures. TheOhio DOT projects continue to be monitored to ensure therepairs are performing as expected.This article is based on a presentation produced by Brad Lightle,director of Planning for District 7 of the Ohio Department ofTransportation, and Chris Ball, vice president of Vector CorrosionTechnologies, Tampa, Fla.Innovative Cost-Effective ProductsFrom a Company You TrustFabric RepairsHistoric Archesby Stacie L. Dovalovsky, Clark Dietz Inc.As the City of Kankakee, Ill., has grown, so too has its needfor improved infrastructure to handle the increased traffic.Updating the Station Street Bridge, built in 1924, requiredcareful consideration and planning to ensure its historicappearance was not altered. To achieve this goal, E-glassreinforcing fabric was used to confine the concrete in thebridge’s arches and to provide protection from the weather.LENTON ® Taper-Threaded Couplers are some of the mostwidely used mechanical rebar splices in the world today.*LENTON ® Concrete Reinforcement Products arespecified in projects worldwide to reduce congestionand speed installation. Cost-effective LENTONproducts from ERICO ® provide reliable performance.* LENTON and LENTON LOCK Couplers meet or exceed the requirements of IBC ® , UBC ® ,ACI ® 318 Type 2, DIN 1045 and BS8110.www.erico.comACI is a registered trademark of the American Concrete Institute. International BuildingCode (IBC) is a registered trademark of the International Code Council. UBC (Uniform BuildingCode) is a registered trademark of the International Conference of Building Officials.The 379-ft-long bridge, listed on the Illinois Historic BridgeList and eligible for the National Register of Historic Places,crosses the Kankakee River with five cast-in-place concrete,open-spandrel arches. Built to carry 1920s-era vehicles andstreetcar tracks, it now carries nearly 7000 vehicles every day.The bridge’s historic status limited the options for repairing thesubstructure and superstructure to meet today’s needs.The deck and spandrel columns had been replaced in 1978, butthe arches had received little attention and were in dire needof repair. City officials had three key goals: bringing the projectin on time, on budget, and with little disruption to the bridge’sappearance. The use of fiber-reinforced polymer compositewrappings for the arches helped to achieve all these goals.42 | ASPIRE, Winter 2009

MAINTENANCE, REPAIR, AND REHABILITATION of concrete bridgesThe 379-ft-long Station Street Bridge inKankakee, Ill., had its five cast-in-placeconcrete, open-spandrel arches repairedwith fiber-reinforced polymer compositewrappings. The repair was accomplishedfor less than original cost estimates.After careful consideration of optionsand selection of the best type ofwrappings, a detailed analysis of thearches was performed to determinethe potential construction sequence.Before the arches could be wrapped,deteriorated concrete had to be removedand replaced. But if too much of thecross-section of the arch was removed,it could fail under the weight of thesuperstructure’s dead load.Conventionally formed concrete andshotcrete were used for repairs, afterwhich the arches were wrapped withthe fiber-reinforced polymer composite.They were then painted to protect thecomposites and to give the repairedconcrete a like-new appearance. Toprovide a consistent look to the entirebridge, the existing concrete not wrappedwas painted to match the repairedsubstructure. All work on the bridgewas performed under the direction ofthe prime contractor, Kankakee ValleyConstruction, Kankakee, Ill.The fabric had been used in Illinois tostrengthen existing columns in highseismicareas, but it had not been usedbefore to strengthen a spandrel archbridge. Initially, engineering estimateshad limited the project to wrappingonly the two exterior arches, whichwere significantly more deteriorated.However, the low bid also allowedthe center arch to be wrapped andthe project to be completed for $1.9million or $600,000 below the originalestimate.The reinforcing fabric improves thestructural integrity of the arches byconfining the concrete, providingprotection from the weather, andpreventing future spalling. Mostimportantly, this approach preservedthe bridge’s historic appearance. Itgives the city a virtually maintenancefreestructure for the next 20 to 25years. Much of the material used onthe project was supplied by Sika Corp.,Lyndhurst, N.J.To further enhance the project’shistory, the existing IDOT-standard lightpoles placed on the sidewalks duringthe 1978 repairs were replaced withhistorical period lighting. The new lightpoles were located on the back of theparapets and out of the sidewalks.Special cantilever pedestals weredesigned for the new lighting; thereby,improving driver and pedestrian safety.The lighting ties into the city’s masterlighting plan and allows for futureexpansion of the period lightingthroughout the neighborhood.Planning for the future is a key goalthroughout Kankakee, especially forits infrastructure needs. This projectprovides a new way to meet those needswhile retaining the city’s historic charmand improving safety at the same time.More detail can be found in the article,“Station Street Repair” published in ICRIConcrete Repair Bulletin, July/August2008._____________Stacie L. Dovalovsky, is a project managerwith Clark Dietz Inc. in Chicago, Ill.The arches on the bridge, which is listed on the Illinois HistoricBridge List and eligible for the National Register of HistoricPlaces, needed to be repaired so that its historic nature was notdisturbed.The contractor’s low bid on the project allowed city officialsto extend the wrapping work to include the center arch andstill have the total cost come in below the original engineeringestimate.ASPIRE, Winter 2009 | 43

The historic Rainbow Bridge near Smiths Ferry, Idaho, had its deteriorating rails replacedwith precast concrete units that were match-cast in color and texture to provide aconsistent look for the entire structure.A Perfect Matchby John Hinman, CH2M HillThe Rainbow Bridge near Smiths Ferry,Idaho, was built in 1933 as a cast-in-placearched structure. Its design has made it astatewide landmark and led to its listing onthe National Register of Historic Places. Butits condition had become less noteworthy,leading to the need for delicate repairs thatwould not tarnish its historic nature. Toaccomplish this, new precast concrete railswere installed, with all pieces cast usingcolor and texture to match the existingpieces.The bridge required significant work,because its rails and decorative featureswere disintegrating, and corrosion wasoccurring in the reinforcement of thestringer ends, bents, and spandrel columns.Under ideal conditions, the bridge couldhave been closed and cast-in-place concretecould have been used to replicate theoriginal design, giving the contractor fullaccess. Unfortunately, this wasn’t feasible,as the bridge had to remain open at alltimes.Initially, work focused on the substructure,stabilizing corrosion in the arches andcolumns with electrochemical chlorideextraction (ECE), repairing stringers, andperforming other patching incorporatinggalvanic anodes and replacement work.Analysis showed that the concretehad retained its strength, but neededto be upgraded to control the corrosiondeterioration caused by significant chloridecontamination from deicing chemicals.The main focus at the deck level wasreplacing 841 ft of rail using precastconcrete sections. This approach was takento ensure the bridge could remain openavoiding traffic next to an unprotectededge. The key to success was finding theproper concrete mixture to ensure thenew components would exactly match theshape, color, and texture of the original rails.On the assumption that the originalconcrete mix comprised local aggregates,considerable scouting was done to findsuitable sources. Concrete cores weretaken from the existing bridge, and thesewere compared to cores taken from newsamples cast with different aggregates.Tinting wasn’t an option, as it would beginto weather and create a disparity. It wasdetermined that some local aggregates weretotally unsuitable, but ultimately a closematch was created. The new concrete isexpected to weather over the next few yearsto closely match the existing components.Casting and erecting the precast concreterails created additional challenges, aseach piece was unique due to the grades,superelevations, and curves. The complexitywas immense, with a lot of individualcustomization needed for most of thecomponents. Expanded polystyrene pieceswere carved using computer-controlledcutters to create the forms for each piece.The resulting forms were coated with plasticto achieve a smooth and durable surface.The surface quality of each cast componentstill required close attention. The work wasoverseen by general contractor MowatConstruction Co. in Woodinville, Wash.,with the precast concrete componentsproduced by Central Pre-Mix Prestress Co.in Eagle, Idaho.Officials at the Idaho Department ofTransportation also implemented acorrosion-mitigation program to preventfurther deterioration. After consideringvarious options, they decided on the ECEmethod in the arches and main piers aroundthe joints and the embedment of galvanicanodes in the concrete-patch repairs in thenon-ECE-treated areas.The ECE treatment reduces the amount ofchloride ions in the concrete and generateshigher alkalinity around the reinforcingsteel, reinstating the passivity of steelreinforcement. It directly addresses thecause of the corrosion from the concrete,with no permanent system left in place tobe operated, maintained, and monitored.Approximately 8000 ft 2 of concrete surfacewas treated in less than two months. TheECE treatment was designed by CorrosionControl Technologies in Sandy, Utah. VectorCorrosion Technologies in Wesley Chapel,Fla., supplied the galvanic anodes andexecuted the ECE work as a subcontractorto Mowat.The result of this careful attention to detailis a design that perfectly blends new andold. The proof is in the enthusiastic responsefrom drivers, who had to crawl past theconstruction and wait for traffic when onlyone lane was open. While many timessuch situations create ill will against theconstruction crews; in this case, drivers wererolling down their windows to complimentthe contractor on how good the bridgewas looking. And, with a comprehensivecorrosion-mitigation strategy in place, thebridge is expected to perform for years tocome.The bridge’s arches and main piers aroundthe joints underwent an electrochemicalchloride-extraction process, while galvanicanodes were embedded in the concretepatchrepairs in other areas.The precast concrete rails were cast in formscreated with expanded polystyrene piecesthat were carved using computer-controlledcutters. Each railing piece is unique, owing tothe grades, superelevations, and curves.This bridge was named the 2007 Projectof the Year by the International ConcreteRepair Institute; for more details on theproject, see ICRI’s November/December2007 issue of Concrete Repair Bulletin, orvisit http://www.icri.org/AWARDS/2007/rainbowbridge.asp._____________John Hinman is principal bridge engineerwith CH2M Hill in Boise, Idaho.44 | ASPIRE, Winter 2009