Long-Term Performance of Polymer Concrete for Bridge Decks (2012)

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26 CHAPTER THREE PERFORMANCE OF OVERLAYS FROM SURVEYS AND INTERVIEWS This chapter reviews performance in the field based on infor- mation from agencies, contractors, and material suppliers. SCOPE OF SURVEYS Surveys were sent to all states and Canadian provinces. The questionnaires are in Appendix A. Each agency was asked to complete a general survey form (“Agency Ques- tionnaire”) and to complete a form for each TPO or group of TPOs (“Information on Each TPO”). If agency forces were used to install the overlay, they were asked to com- plete an “Agency-as-Installer Questionnaire.” Few states completed the form for the individual TPOs. Follow-up telephone interviews were conducted with representatives from the agencies that had constructed the greatest num- ber of TPOs. Materials suppliers and contractors identi- fied by the agencies were then interviewed by telephone to obtain information. GENERAL RESPONSES Responses were received from 40 states and seven prov- inces. Seven states and three provinces reporting have never used TPOs. Table 1 summarizes the findings. The informa- tion includes • Number of overlays placed. Approximately 2,400 TPOs have been installed by the states and 147 by the provinces reporting, a fourfold increase over the 555 reported to have been installed through 1999 (4). California has placed the most (520), but each of seven other states, Missouri, Virginia, New Mexico, Michigan, Ohio, Kansas, and Utah, and one province, Alberta, has placed 100 or more. • Ohio and North Carolina reported the first use of TPOs in the 1970s. Four states (California, Missouri, Oregon, and Virginia) and Alberta began applying overlays in the 1980s. • Three states (Florida, Iowa, and Montana) and two provinces (Alberta and British Columbia) no longer use TPOs. Florida indicated that it had installed 30 on seg- mental bridges but does not have deck problems; Iowa had installed one and indicated that it performed poorly; and Montana had installed 30 to 35, but stated that administrative problems made it too time consuming to enforce the specifications. Alberta has constructed 139 TPOs, with the last one placed in 1999, but plans to use no more in the future. Alberta experienced some problems with TPOs placed initially, but when those problems were resolved, the overlays performed well. Eventual problems with achieving adequate inspection and wet, rainy conditions in some parts of the province were reasons cited for discontinuing their use. British Columbia installed two but reported high cost and poor performance as reasons for no longer using them. • Most of the states indicated more than one reason for the use of TPOs; improving skid resistance was the most often cited reason, with extending the life of the deck the next most cited. Other reasons included repairing spalled and cracked surfaces, restoring a uni- form appearance, and waterproofing the deck. • Nearly all states use epoxy resins. Many did not respond as to the construction type, but the majority of states that did indicated that multiple layer was the preferred method. California was an exception, having installed over 500 premixed polyester overlays. Other West Coast states also use premixed systems. • The majority of states use contractors for installation, but 10 states use their own forces for at least some installations. • New Mexico, Georgia, and LaGuardia Airport require warranties ranging from 1 to 10 years. • Many states have specifications available. OVERLAY COST Three states reported overlay costs. Virginia reported a cost of $60/m2 ($50/yd2) for an epoxy multiple-layer TPO installed by a contractor in 2005, and Alaska reported a cost of $114/m2 ($95/yd2) for an epoxy-urethane TPO installed by a contractor in 2007. Kansas DOT reported that between 2001 and 2008 the cost of shot blasting and placement of TPOs averaged $66/m2 ($55/yd2).

27 T A B L E 1 S U M M A R Y O F S T A T E S A N D P R O V IN C E S S U R V E Y S ta te N o. P la ce d Fi rs t/ L as t Y ea r F ut ur e T P O s R ea so ns f or U se T P O S ys te m In st al le r W ar ra nt y, Y ea r Fa il ur es S pe cs A va il . C om m en ts A K 2 20 07 Y es l, a, w P P M A ge nc y N /A N o N o E xc es si ve w ea r in ti re la ne s A L 31 19 92 /1 99 4 Y es sf , l , a , s , w A ny A ge nc y N /A N o N o A R 0 N /A N /A N /A N /A N /A N /A N /A N /A A Z N o st at e D O T T P O s C A 52 0 19 83 /2 00 8 Y es sf , l , s , w P P M C on tr ac t N /A Y es S en t P P M , E M L S no w c ha in r ut ti ng p ro bl em s C O U se d, b ut n o in fo rm at io n av ai la bl e C T N ot u se d D E 1 20 07 Y es l E M L N /A N /A N o N o T oo e xp en si ve F L 30 20 00 /2 00 3 N o w H M W M s ea le r N /A N /A N o N o P ro te ct c ab le s in s eg m en ta l br id ge s G A 10 M id -1 99 0s /2 00 7 Y es sf , l , a E U M L C on tr ac t 10 N /A S en t E M L H A 0 N /A N o N /A N /A N /A N /A N /A N /A IA 1 19 86 N o T ri al N /A N /A N /A N /A N o P oo r pe rf or m an ce ID 2 20 03 /2 00 7 Y es sf , l , w E M L , E U M L N /A N /A N /A N /A IL 24 19 96 /2 00 7 Y es l, w E M L C on tr ac t N /A Y es S en t E M L K S 10 0 + 13 a 19 99 /2 00 9 Y es w , l , s E M L C on tr ac t N on e 1 E M L F ai le d du e to d ec k co nt am in at io n M D 1 20 00 N /A w E M L A ge nc y N /A S m al l c ra ck s N o W or ke d pr et ty w el l M E 1 1 br id ge T P O D O T I ns ta ll at io n M I 10 0s 19 95 /2 00 7 Y es sf , l , a , s E M L C on tr ac t, ag en cy N /A Y es Y es P oo r bo nd f ro m p oo r su rf ac e pr ep M S N o in fo rm at io n av ai la bl e M N 5 20 06 /2 00 7 Y es sf , l , w E M L A ge nc y N /A N o N /A M O > 30 0 19 89 /2 00 7 Y es sf , l , a , w E M L , E U M L , E P M C on tr ac t N /A Y es S en t M T 35 19 95 /2 00 0 N o N /A N /A C on tr ac t N /A Y es N o In sp ec ti on p ro ce ss Q C /Q A di ffi cu lt ie s N C 50 19 75 /1 99 0 Y es w E M L A ge nc y N /A Y es N o N D U se d, b ut n o in fo rm at io n av ai la bl e N E 0 N /A N o N /A N /A N /A N /A N /A N /A N H 2 E U M L C on tr ac t Y es Y es Im pr ov e sk id r es is ta nc e, li fe an d lo ok o f br id ge Ta bl e 1 C on ti nu ed o n p. 28

28 Ta bl e 1 C on ti nu ed f ro m p .2 7 S ta te N o. P la ce d Fi rs t/ L as t Y ea r F ut ur e T P O s R ea so ns f or U se T P O S ys te m In st al le r W ar ra nt y, Y ea r Fa il ur es S pe cs A va il . C om m en ts N J 0 N /A N o N /A N /A N /A N /A N /A N /A N M 25 0 19 95 /2 00 8 Y es sf , l , a , s , w E M L , E U M L C on tr ac t, ag en cy 5 Y es O nl in e In sp ec ti on p ro ce ss Q C /Q A di ffi cu lt ie s N Y 44 19 99 /2 00 7 Y es l, w M P M , E M L , E U M L , P M L C on tr ac t N /A O nl y on e M M A S en t W ea ri ng s ur fa ce a gg s O H 14 7 + 1 5 + 1b 19 79 /2 00 6 Y es l, s E M L A ge nc y, po ly ca rb N /A Y es N o O ve r 10 0 fa il ur es in la te ’ 90 s O K 10 20 03 /2 00 7 Y es sf , l , w E M L , E U M L N /A N /A N /A N /A O R 35 19 81 /2 00 7 Y es l, s, w E M L , P P M , M P M C on tr ac t N /A Y es N /A M os tl y fo r tr ac ti on S C L es F lo yd , n ot u se d S D 0 N /A N o N /A N /A N /A N /A N /A N /A T N 3 20 00 /2 00 5 Y es sf , l , w E M L C on tr ac t N /A N /A N /A T X 12 19 98 /2 00 8 Y es sf , l , a , s , w E M L C on tr ac t N /A N /A N /A U T 10 0 20 01 /2 00 7 Y es sf , l , w E M L C on tr ac t N /A N /A N /A T oo e xp en si ve V A 30 0 19 81 /2 00 8 Y es sf , l , a , s , w E M L , P M L , P P M , M P M C on tr ac t, ag en cy N /A N /A Y es B ri dg e de ck p re se rv at io n W V 8 19 97 /2 00 7 Y es sf , l , w E M L , U M L N /A N /A N /A N /A W Y 61 19 90 /2 00 5 Y es sf , s E M L C on tr ac t, ag en cy N /A Y es Y es M os tl y fo r tr ac ti on C an ad ia n P ro vi nc es A B 13 9 19 84 /1 99 8 N o N /A N /A N /A N /A N /A N /A P oo r pe rf or m an ce , t oo ex pe ns iv e B C 2 19 90 /1 99 1 N o N /A N /A N /A N /A N /A N /A P oo r pe rf or m an ce , t oo ex pe ns iv e M B 0 N /A N o N /A N /A N /A N /A N /A N /A N B 5 20 05 /2 00 7 Y es l, s, w E M L A ge nc y N /A Y es N /A N S 0 N /A N o N /A N /A N /A N /A N /A N /A N T 1 19 91 Y es s, w E M L C on tr ac t N /A N /A S en t O N 0 N /A N o N /A N /A N /A N /A N /A N /A P oo r pe rf or m an ce , t oo ex pe ns iv e N O T E . s f = r es to re s ur fa ce f ri ct io n; l = e xt en d li fe o f de ck , i nc lu di ng a dd it io na l c ov er ; a = r es to re u ni fo rm a pp ea ra nc e of d ec k su rf ac e; s = r es to re s ur fa ce to p re vi ou s sp al le d, c ra ck ed , a nd r ep ai re d de ck ; w = w at er pr oo f de ck ; P = p ol ye st er -s ty re ne ; E = e po xy ; E U = e po xy u re th an e; H M W M = h ig h- m ol ec ul ar -w ei gh t m et ha cr yl at e; M = m et ha cr yl at e (s lu rr y) ; P M = p re m ix ed ; M L = m ul ti pl e li ft ; N /A = in fo rm at io n no t a va il ab le f ro m ag en cy . b 1 47 b y O hi o, 1 5 by c ou nt ie s, 1 b y ci ty . a 10 0 by K an sa s, 1 3 by c ou nt ie s.

29 Illinois Bridge Deck Thin Polymer Overlay, Illinois Department of Transportation, Springfield, Jan. 1, 2007, http://www.dot. state.il.us/materials/polymeroverlaysystems.pdf. Kansas Multiple-Layer Polymer Concrete Overlay, www.ksdot.org/ burConsMain/specprov/pdf/729.pdf; www.ksdot.org/bur- ConsMain/specprov/2007/pdf/07-07013.pdf. Michigan Thin Epoxy Polymer Bridge Deck Overlay, Michigan Department of Transportation, Special Provision, Dec. 29, 2005, http://www.michigan.gov/documents/mdot/MDOT_ Research_Report_RC1422_200642_7.pdf. Missouri Epoxy Resin Material, Section 623, Missouri Department of Transportation, http://www.modot.mo.gov/business/stan- dards_and_specs/Sec1039.pdf. Montana http://www.mdt.mt.gov/publications/manuals.shtml. New York https://www.nysdot.gov/spec-repository/584.50----03.pdf; https://www.nysdot.gov/spec-repository-us/584.40000006.pdf. North Carolina SBE Program Contracts (see the section on Epoxy Coating Systems), http://www.ncdot.org/doh/Operations/division1/ BID_LISTINGS/10808683.pdf. Ohio Epoxy Waterproofing Overlay for Bridge Decks, Proposal Note 514, Ohio Department of Transportation, Sep. 24, 1992, http://www.ohiopavementselection.org/construction/OCA/ Specs/SSandPN2002/pn5140402for2002.pdf. Oregon Section 00557—Premixed Polymer Concrete Pavement Over- lays, http://www.oregon.gov/ODOT/HWY/SPECS/docs/ 08specials/Updates/01-14-10/SP557.pdf. CAUSES OF FAILURES From the surveys, both written and telephone, causes of fail- ures were identified and included the following: • Deck condition—in many cases, overall condition of deck probably too poor to apply overlay; • Repaired areas not sufficiently dry and/or not roughened; • Inadequate surface preparation; • Cool damp weather during installation; • Deck too damp at time of overlay installation; • Construction problems; • Inadequate quality control; and • Use of snow chains. SPECIFICATIONS Specifications were requested from agencies, and the states submitting specifications included the following: California Method of Testing for Determining Suitability of Materials for Overlayment and Repair of Portland Cement Concrete Pave- ment and Structures, California Test 551, Engineering Ser- vice Center, Department of Transportation, Sacramento, Feb. 2000, http://www.dot.ca.gov/hq/esc/ctms/pdf/CT_551.pdf. www.dot.ca.gov/...structurespecs/.../UpdatedMetricSpecs/ 51-806_B07-02-09.doc. www.dot.ca.gov/... /st r uctu respecs /...04SPECS/... / 51-806(51POVR0_R02-14-07.doc. Prepare Concrete Bridge Deck Surface, Engineering Service Center, Department of Transportation, Sacramento, http://search.ca.gov/search?site=ca_dot&client=ca_ dot&output=xml_no_dtd&proxystylesheet=ca_dot& q=Prepare+Concrete+Bridge+Deck+Surface&submit. x=13&submit.y=6. Polyester Concrete Bridge Deck Surface, Engineering Service Center, Department of Transportation, State of Cal- ifornia, Sacramento, http://www.kwikbondpolymers.com/ product/application/sample_spec.pdf. Georgia Two-Part Epoxy-Urethane Co-Polymer Bridge Deck Over- lay, Section 519, Department of Transportation, Georgia, Special Provision, Sep. 23, 2002.

30 Repair Materials Repair materials included polymer concrete, latex modified concrete, magnesium phosphate, proprietary fast-setting concretes, and high alumina cement concrete. One indicated that the California Department of Transportation specifica- tion requires a 72-hour cure for magnesium phosphate and 1 hour for high alumina cement. In another case, 3 days were required for fast-setting materials to cure before overlaying the repair. Installation Shot blasting was the cleaning method used on flat work; in some cases, grit blasting was used on curbs and gutters. It was indicated that if the shot clogs in the shot blaster, the deck is too damp and provides a good control. They repair just before installing the overlay. All of them installed epoxy multiple-layer TPOs; one also installed MMA slurry and premix, and the other installed deicing overlays. One con- tractor permits traffic on the first layer after it cures and then shot blasts the first layer the next day and immediately places the second layer. He uses 550 shot for the first application and 460 for the second. One performed mixing as specified, including a completely automated system using a mobile batching machine and modified asphalt paver. Another used concrete mixers, wheelbarrows, and screeds on rails. Problems Encountered Contractors encountered the following primary problems: • Weather: rain or high or low temperatures; • Cure times related to traffic openings: resin cured too slowly to open as required by contract; • Quantities of materials: plans always indicate less than required; • Day or night temperatures affect the work time and volume of materials that can be placed; • Deck condition: decks are often in badly deteriorated condition; some DOTs assume that a polyester pre- mixed TPO can restore a deteriorated deck with 18- to 150-mm (0.75- to 6-in.) premixed polyester TPO as needed to restore ride quality; the inevitable deteriora- tion of the TPO is usually blamed on the contractor; • Moisture in deck: excessive moisture reduces bond strength. Recommendations Contractor recommendations include that— • Bidders be prequalified for TPO experience; • Resin manufacturer’s representative always be present, especially if warranty is required; Texas Multiple-Layer Polymer Concrete Overlay, ftp://ftp.dot. state.tx.us/publ/txdot-info/cmd/cserve/specs/2004/spec/ ss4429.pdf; ftp://ftp.dot.state.tx.us/pub/txdot-info/cmd/ cserve/specs/1993/spec/es7675.pdf; ftp://ftp.dot.state.tx.us/ pub/txdot-info/cmd/cserve/specs/…/spec/ss4398.pdf. Utah www.dot.state.uut.us/main/uconower.gf?n=504434814 209249743. Virginia http://www.aot.state.vt.us /conadmin/Document/Sec- tion%20900%20Items/THINPOLYMEROVERLAY.pdf. Contact the California, New York, and Virginia DOTs for specifications through their websites. MATERIALS Resin Systems Epoxies are preferred by states, with some states using epoxy-urethanes; specifications requiring a minimum tensile elongation of 30%. One company, however, sup- plies the majority of the polyester premix used in North America. One state specifies 20% tensile elongation, and one state specifies brand names of low-modulus epoxies. California uses polyesters and requires a minimum elonga- tion of 35%. CONTRACTOR INTERVIEWS Nine contractors having considerable experience with TPOs were interviewed by telephone. The contractor ques- tionnaires are in Appendix A. These nine contractors had installed hundreds of TPOs in many states. Condition of Bridges Most of the bridges on which they had installed TPOs ranged from sound to seriously deteriorated, but generally they were moderately distressed. Most bridges had been previously repaired, and at least four had repairs of the sub- strate performed as part of the TPO installation contract. One contractor said that 80% of his jobs have been on older bridges that had been repaired, and virtually all contracts involved some repair work before the TPO was installed. Another contractor said that 90% of the bridges he works on are deteriorated.

31 • Repairs be made using compatible polymer patching materials supplied or specified by the TPO manufac- turer, which eliminates paying for traffic control twice and having to build in an extra 28 to 56 days to let the patches cure, dry, and outgas; • Diamond grinding be specified for very rough decks to save on the cost of shot blasting and to minimize the resin consumption; • A mandatory 4-hour curing period is too long in hot weather; 1 hour is often enough and can be verified by the impact hammer and/or screwdriver test; peak exotherm or maturity might also work to confirm the curing, especially for thicker overlays; • The specifications requiring the airless spray applica- tion for high-molecular-weight methacrylate sealers and primers be eliminated because of the difficulty in keeping the spray guns calibrated; by the time the problem is discovered, considerable improperly mixed resin has been applied; • TPO applications always be restricted to warm and dry periods; and • Warranties for 5 years be required. MATERIAL SUPPLIER INTERVIEWS Seven material supplier representatives were interviewed by telephone. The questionnaires are in Appendix A. Two suppliers had been involved with approximately 1,000 TPOs and another two with hundreds each. The others, however, were involved in at least 10 bridges. Their companies pri- marily supply epoxy resin systems. One company, however, supplies the majority of the polyester premix systems used in North America. Collectively, they have worked in 13 or more states and Canada. Problems Encountered Material suppliers observed the following problems that may lead to poor performance of TPOs: • Poor deck condition; • Cracking and delamination of deck; • Inadequate concrete cover on steel; • Bidding followed by requirement that they must pro- vide technical support on site; and • Obtaining all three surface preparation requirements: clean, dry, and sound. Recommendations To improve the quality of TPOs, material suppliers recom- mend that— • Technical representatives be trained; • Manufacturer’s representative be on site to oversee work; • The deck be in good condition; • Deck be clean and dry; • Deck cleaning texture be specified as ICRI CSP 7, but can accept 6; • Multiple-layer TPOs be used for epoxy systems; • Minimum tensile elongation be 50% for epoxy systems; • Aggregate have a Mohs hardness of 7; • AASHTO Task Force 34 recommendations (6) be followed; • For polyester systems specifications, have contractor make an investment in volumetric mixers with readouts and plural components, paving machine with automatic grade control, and shot-blasting equipment; and • Specification must require experience.