Control of Concrete Cracking in Bridges (2017)

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88 Appendix B Summary of Responses to Survey Questionnaire This appendix contains a summary of the responses to the questionnaire. Only those agencies that submitted responses to the questions are listed. 1. IntroductIon Responses to the survey were received from the following U.S. highway agencies and Canadian Provinces: u.S. States Alabama New Hampshire Alaska New Jersey Arizona New Mexico Arkansas New York California North Carolina Colorado North Dakota Delaware Oklahoma Florida Oregon Illinois Pennsylvania Iowa Rhode Island Kansas South Dakota Louisiana Tennessee Maine Texas Massachusetts Utah Michigan Vermont Minnesota Virginia Mississippi Washington Missouri Wisconsin Montana Wyoming Nevada canadian Provinces Alberta Prince Edward Island Manitoba Saskatchewan Ontario Yukon 2. General 1. Which of the following types of concrete cracking has your agency experienced in the past five years on bridges with precast, prestressed concrete beams? If your agency does not use a particular system, check Not Applicable. Type of Concrete Cracking Number of Agencies Never Infrequently Frequently Always Unknown Not Applicable Cracking in cast-in-place concrete decks with removable formwork 1 7 22 4 2 9 Cracking in cast-in-place concrete decks with stay-in-place metal forms 0 9 13 2 1 19 Cracking in cast-in-place concrete decks on precast concrete deck panels 0 5 10 4 4 21 Cracking at locations other than the connections in full-depth precast concrete deck panels 1 13 4 1 4 22 Cracking at the connections in full-depth precast concrete deck panels 1 4 6 3 7 24 Cracking in the cast-in-place concrete decks above the longitudinal connections in adjacent box beam or slab beam bridges 0 12 12 6 3 12 Cracking in the longitudinal connections between adjacent box beam or slab beam bridges when a cast-in-place topping is not used 0 10 10 2 4 18 Vertical cracks in pretensioned concrete beams prior to transfer of prestressing force 10 22 1 1 8 2 End splitting cracks in prestressed concrete beams 9 24 4 3 5 0

89 2. Which of the following types of concrete cracking has your agency experienced in the past five years on bridges with steel beams? If your agency does not use a particular system, check Not Applicable. Type of Concrete Cracking Number of Agencies Never Infrequently Frequently Always Unknown Not Applicable Cracking in cast-in-place concrete decks with removable formwork 0 8 23 6 0 8 Cracking in cast-in-place concrete decks with stay-in-place metal forms 0 11 15 2 1 15 Cracking in cast-in-place concrete decks on precast concrete deck panels 0 4 6 5 3 27 Cracking at locations other than the connections in full-depth precast concrete deck panels 1 9 4 0 2 28 Cracking at the connections in full-depth precast concrete deck panels 0 4 8 3 3 27 3. Which of the following types of concrete cracking has your agency experienced in the past five years on bridges with concrete or steel beams? Type of Concrete Cracking Number of Agencies Never Infrequently Frequently Always Unknown Not Applicable Cracking in non-prestressed concrete beams 1 10 8 1 2 23 Cracking in pier caps 5 26 10 1 2 1 Cracking in columns or abutments 6 29 6 1 2 1 Cracking in pile caps 5 27 5 2 5 1 4. What lessons has your agency learned about controlling concrete cracking? Specific case studies would be useful for the synthesis. Please list any reports or attach files in Question 29. Agency Lessons Learned Alaska Caution must be taken to not over-heat concrete during cold weather concreting operations or cracking may occur. California Caltrans has determined that, when a shrinkage reducing admixture is used and 28-day shrinkage is limited to 0.032 (measured by AASHTO T-160 with 4×4 prism), deck cracking from dry shrinkage can be eliminated or significantly reduced and that polyolefin fibers and good misting practices prevent plastic shrinkage cracks so that longer term drying shrinkage performance can be evaluated. Colorado Better cure times, use of fibers in slope paving and sidewalks. for case studies check our website/library/research/find topics alphabetical Delaware Mix qualification for ASR mitigation. Florida FDOT current policy for crack control in pier caps and columns is a 24 ksi upper limit under Service III. Attached paper shows theoretically inconsistent crack widths with this approach. The change suggested by this paper has not been implemented. There is internal discussion on whether or not to adopt this new approach. Iowa Concrete cracking is not controlled by the type of reinforcing used. Cracking is controlled by using proper curing methods and concrete mixes. Nothing will eliminate cracking in concrete. Corrosion resistant reinforcing helps prevent corrosion induced cracking. Kansas The majority of our cracking appears related to drying shrinkage, so limiting the paste and going with an increased curing period (14 days) has reduced cracking. Paste content is indirectly controlled through permeability. Louisiana Concrete curing must be done properly as per our concrete construction specifications. Maine The importance of wet curing. Timely application of wet curing. Missouri Modified B-2 concrete to reduce cement content. New Hampshire All concrete cracks New Mexico Control of conditions to prevent plastic shrinkage cracking has helped. New York Cracking generally happens in concrete construction mainly due to restrained shrinkage and thermal effects. Controlling crack widths using appropriate reinforcement, along with sealing of cracked concrete with penetrating type sealers and/or healer sealer application can reduce the negative effects on the durability of reinforced concrete exposed to adverse environments. NYDOT also has recently completed a study on the use of internal curing high performance concrete for CIP concrete decks. The study found that internal curing concrete is beneficial in reducing deck cracking.

90 Agency Lessons Learned Oklahoma ODOT participated in the University of Kansas pooled research on crack free bridge decks http://www.concretebridgeviews.com/i78/Article2.php Oregon OSU State Research Report 728. This research developed shrinkage limits to reduce deck shrinkage. The limits were implemented in 2016. Anecdotal research and trial batching has determined that concrete fibers help control cracking. Pennsylvania A Pro Team was assembled including members from all across the state for the purpose of controlling concrete deck cracking. A pilot program was launched for 2015 including bridge decks all across the state. This included modifications from the standard specifications for deck concrete including reducing the maximum cementitious, shrinkage and permeability. The specifications are attached as well as the interim report created for FHWA. Rhode Island Most cracking is related to plastic or prying shrinkage and can be addressed by mix design and curing. Don’t have solution for reported cracking. South Dakota There are many factors that can influence concrete bridge deck cracking. As of yet the right combination of materials, placement and curing methods has not been identified to prevent/control North Dakota Member of Crack Free Bridge Deck Pooled Fund. Research conclusions are available. the cracking in SDDOT bridge decks. Tennessee Place additional re-steel in the negative moment region of the deck seems to help control cracking. Utah Contact the UDOT Materials Division Virginia Reduce Cement content to minimize total water volume (w/c ratio stays at .45). Add shrinkage reducing admixture. Both reduce drying shrinkage cracks Washington Using performance-based mix has reduced deck cracking on concrete bridges. Wisconsin WHRP Project 0092-15-01 Precast/Prestressed Concrete Bridge Girder Cracking Phase II is expected to be completed in 06/2016. Alberta Mix designs, curing requirements, and construction detailing are critical specification considerations to reduction potential for cracking. Regardless of the girder type or deck system used the potential for deck cracking exists. System restraints result in conditions for cracking to occur. Alberta Transportation has required shrinkage testing on Class HPC concrete use for bridge decks and an evaluation of the data has been completed. The intent of the evaluation was to develop shrinkage performance requirements. Ontario Adequate curing (i.e., carry out curing in strict accordance with specification). MTO requires wet curing for all structural concrete. Use of retarder to maintain bridge deck concrete in plastic state until all concrete is placed. Use of pour sequences on long structures. Use of higher strength mixes and high performance concrete, including self-consolidating concretes, requires even more careful attention to curing. Prince Edward Island We no longer permit the use of curing compounds and specified a full seven day continuously wet cure. This has mitigated a lot of cracking; however, it hasn’t eliminated all of it. Saskatchewan Proper moist curing at the time of concrete placement. Adjustment of mix design to reduce cracking and shrinkage. 3. BrIdGe decKS (canadian participants go to question 6.) 5. Does your agency use Article 5.7.3.4—Control of Cracking by Distribution of Reinforcement of the AASHTO LRFD Bridge Design Specifications, Seventh Edition to determine maximum spacing of reinforcement in bridge decks? Yes with no changes: 26 U.S. agencies Yes with modifications: 8 U.S. agencies No: 4 U.S. agencies If “Yes” or “Yes with modifications,” what value of the exposure factor, γe, does your agency use? Arkansas 1 U.S. Agency Modification Alaska 0.75 in most cases Arizona 0.75 California 0.75 Florida As per SDG 4.1.8 or 3.10 Kansas 1.00 bottom steel, 0.75 top steel Louisiana We have defined the Class 2 exposure conditions as per our specific La. map in our bridge manual. Massachusetts 0.75 Missouri 0.75 for Class 2 exposure condition Montana The conservative one in the code. New Hampshire 0.75 for Class 2 Exposure condition New York Designer is to determine the value based on the exposure condition and appearance requirements. Oklahoma 0.75 Oregon For bridge decks, exposure factor = 1.0; for other elements, exposure factor = 1.0 for moderate exposure, 0.75 for severe exposure (deicing chemicals, corrosive environment, etc.) Pennsylvania 1.0 for exposure 1, 0.75 for exposure 2. The same as AASHTO. Rhode Island 1.0 for Class 1, 0.75 for class 2 South Dakota 1.0 for box culverts & substructures; 0.75 for bridge decks Tennessee Exposure factor = 0.88 (corresponds to a crack width of 0.015 mm) Utah See the UDOT Structures Design and Detailing Manual http://www.udot.utah.gov/main/f?p=100:pg:0:::1:T,V:1730. Wisconsin 0.75 Wyoming 1.0 Class I exposure

91 If your agency has modifications or design practices to supplement Article 5.7.3.4, what are they? U.S. Agency Modification Florida Decks made continuous (link slabs) have supplementary reinforcing. See SDG 3.10, 4.1.8, 4.2.4, 4.2.6 & 4.2.8 for additional modifications. Iowa IDOT uses the Z-check rules in the AASHTO LRFD Specs prior to the 2005 Interims. Kansas Max cover for equations of 2 in., real cover 3 in. Louisiana Max. value of dc shall be 2 inches plus the radius of the flexural reinforcement closest to the tension fiber. Massachusetts In addition, the quantity of steel was checked against the recommended minimum amounts identified in a study* initiated by the Indiana Department of Transportation (INDOT). This study recommends additional reinforcement above current practice to control transverse crack widths in concrete decks. It provides a formula for calculating a minimum total amount of longitudinal reinforcement in the section. *Frosch, R.J., D.T. Blackman, and R.D. Radabaugh, “Investigation of Bridge Deck Cracking in Various Bridge Superstructure Systems,” Joint Transportation Research Program, FHWA/IN/JTRP-2002/2.5, 160 pp. Oregon We limit compressive stress in concrete at service limit state due to positive bending moment between girders to 0.4 f'c. We limit bar spacing in bridge decks to 8" maximum. We limit rebar size in bridge decks to be smaller than or equal to #6 bars. Pennsylvania The following shall replace the definition of dc in A5.7.3.4. dc = thickness of concrete cover measured from extreme tension fiber to center of the flexural reinforcement located closest thereto (in.). The (½ in.) wearing surface for deck slab, top and bottom slab of box culvert and (1 in.) extra cover provided to account for uneven ground level of footing bottom mat reinforcement and bottom Maine Maine DOT’s Bridge Design Guide has standardized deck designs and Article 5.7.3.4 is rarely used on most designs. slab of box culverts, shall not be included. The following shall supplement the third paragraph of A5.7.3.4. Class 1 applies to all reinforced concrete members except precast and cast-in-place box culverts, segmental construction and for the specific conditions defined under Class 2. Class 2 exposure also applies to precast and cast-in-place box culverts. The following shall replace the fourth paragraph of A5.7.3.4. In the computation of dc, the actual concrete cover thickness is to be used except in deck slabs, box culvert slabs and footings as defined in dc. Rhode Island Redistribution percentage in terms of c/deratio Utah http://www.udot.utah.gov/main/f?p=100:pg:0:::1:T,V:1730. 6. What strategies does your agency currently use to minimize cracking in full-depth, cast-in-place concrete bridge decks? Strategy No. of Responses Yes No None 2 19 Specify minimum cementitious materials content 23 16 Specify maximum cementitious materials content 20 19 Specify minimum concrete compressive strength 34 4 Specify maximum concrete compressive strength 4 35 Specify a ratio between 7- and 28-day compressive strengths 3 35 Specify minimum concrete temperature at placement 34 6 Specify maximum concrete temperature at placement 37 4 Specify maximum concrete temperature during curing 23 15 Specify maximum water-cementitious materials ratio 39 2 Specify maximum slump 36 5 Specify maximum water content 20 18 Specify the use of a shrinkage-reducing admixture 9 30 Specify the use of a shrinkage-compensating concrete 6 32 Specify the use of fibers 10 30 Require use of the ACI surface evaporation nomogram 25 15 Require wind breaks during concrete placement 15 24 Require evaporation retardants 13 26 Specify internal curing 4 34 Require fogging during placement when evaporation rates are high 27 13 Specify a minimum wet curing period 40 2 Other 11 12 If “Other” or only used under special circumstances, please list. Agency Other Strategy or Special Use Arkansas ACI nomograph use and precautions are recommended in internal Resident Engineers ’ Manual. 6% lithium silicate curing compound and sealant is allowed as contractor substitution for curing compound and wet cure. Florida SRAs and fibers are used for special applications. Evaporation retarders can be used at the option of the contractor. Seven-day wet curing is required for bridge decks. Illinois Though we do not specify shrinkage compensating materials, shrinkage reducing admixtures, or internal curing, we have developed special provisions for such items to be used at the discretion of our Districts. We are currently researching the benefits and optimization potential of all three items, and have built 2 Type K decks and 2 SRA decks in recent years. We have just released our internal curing specs and hope to have a District or two try it soon. We are also trying a textured epoxy- coated rebar that “bonds” to the concrete like black bar.

92 Agency Other Strategy or Special Use Iowa Require retarding admixture to maintain concrete plasticity during beam/girder deflection when continuous placement. Kansas A minimum strength and cement content is not intended to limit cracking. Louisiana Total air content, percent by volume. New Hampshire NHDOT approves a contractor submitted QC plan to evaluate and control evaporation. New York NYSDOT is prescribing a standard High-Performance Concrete mix for bridge decks. Internal curing has been tried on a limited number of decks during last five years. Based on the observed beneficial effects NYSDOT is planning to expand the use of internal curing concrete for deck applications. Oklahoma For bridge decks, we require 7 day’s wet cure followed by 7 days of membrane cure. Rhode Island Have a required maximum shrinkage for some mix designs, based on class of concrete. Texas Three of the 25 districts in TxDOT specify micro-fibers to reduce plastic shrinkage cracking. Utah Refer to the UDOT Specifications for Structural Concrete Wyoming Take action to reduce evaporation such as provide shade, use ice, or other cooling methods and provide wind barriers. Evaporation retardants and fogging are not required but both have been used and are accepted methods when proposed. 7. What strategies to minimize cracking in full-depth cast-in-place concrete bridge decks have been most effective? Agency Strategy California Limiting drying shrinkage and mandating shrinkage reducing admixture paired with good misting and polyolefin fibers to prevent plastic cracking Florida Currently, 7-day wet curing of decks, then curing compound. We are researching the use of internally cured concrete for deck applications as well. Iowa 1. Evaporation control 2. Reduction in portland cement 3. Requiring retarding admixture for continuous placements Kansas Increased curing period (started within 15 min.) and reduction of paste content. Louisiana Proper curing. Maine Hard to say what has been most effective since we are still seeing cracking in full depth cast in place bridge decks. Michigan Night casting Minnesota Fibers, and wet cure Missouri Modified B-2 concrete and extend curing period to minimum 7 days New Hampshire NHDOT mainly places a torch applied waterproof membrane over its concrete decks and 2.5" asphalt wearing surface. New Jersey Wet curing New Mexico Wind break, fogging system, staggering of top and bottom transverse bars by one-half bar spacing. New York Temperature control of concrete at the time of placement, application of curing method without significant delay and the use of internal curing. Avoiding late season placements which will need addition of external heat also appears to be beneficial. Staged placement of decks, most of the positive moment areas first and the negative areas after 72 hours appears to be beneficial. Oklahoma We did an experimental deck (research is still preliminary) with pulpcure: Pulpcure was developed at Oklahoma State University under Dr. Ley. Pulpcure is made up of recycled newspaper, water, and chemical admixtures to help it flow while staying cohesive. It can be applied with minimal labor. The raw materials are pumped to the surface of the concrete and evenly applied. In the laboratory and on field applications, pulpcure has shown the ability to hold the moisture for longer periods than saturated wet burlap. The challenge has been to find a good way to apply it to a 40' wide bridge deck in a timely manner without damaging the deck surface. The material is biodegradable. Oregon Use of fibers. Keep concrete strength around 4000 psi. Pennsylvania Reducing the maximum cementitious, optimizing aggregates to reduce the paste content, setting limits on permeability and shrinkage. Rhode Island All the above “yes” answers. Reduction of silica fume in the mix. Virginia 1. Limits on total paste; 2. Shrinkage reducing admixtures; 3. Allow lower compressive strength in decks; 4. Allow contractor additional time before traffic is applied to deck. Wisconsin Immediate fogging and application of wet burlap; Seven-day wet cure. Wyoming Monitoring evaporation rates with max at 0.2 lb/sf/hr, max w/c ratio at 0.45, timely curing. Looking at shrinkage-reducing admixtures. Alberta Appropriate mix design and use of cementing materials, wet curing requirements. Use of combined supplementary cementing materials (fly-ash & silica fume) to reduce shrinkage potential and slow hydration processes. Ontario As above. Require placement of wet burlap curing within 2–4 m of finishing machine (on bridge decks) and within 2–4 m of finishing operation for other elements. Plastic placed over burlap and soaker hoses to maintain burlap in wet condition over 4-day (or 7-day) curing period. Fog misting required for high performance concretes, during placement in bridge decks. For all bridge decks and for large (>1 thick) elements, require measurement of concrete temperature by thermocouples and data logger at centroid and extremities during curing period, to verify temperature limits are met. Prince Edward Island Minimum wet curing period. Massachusetts To specify minimum wet cure period and to require fogging during concrete placement Saskatchewan Fogging and immediate placement of wet cure blankets. Yukon By following all concrete quality control measures. North Dakota Wet cure applied within 15 minutes of paver placement. Keep wet continuous throughout curing period.

93 8. What strategies to minimize cracking in full-depth cast-in-place concrete bridge decks have been least effective? Agency Strategy Arkansas Unknown because unequal application of specifications and substitutions create variable risk of cracking. However, increases in cracking roughly tracks larger continuous pours requested by contractors and longer spans. Florida No curing at all. Curing is a necessity here in Florida due to our high temperatures and windy conditions near the coast line. Illinois What we’re currently doing doesn’t appear to be very effective. Iowa Use of extended wet curing periods. Kansas Evaporation retardants, at best belt and suspenders with a good curing process. At worst, more water added to the surface. Louisiana Contractor not curing properly as per our specifications. Maine Refer to #7. Michigan Continuous decks for live loads. New Jersey Not providing proper wet curing. New York Use of set retarding admixtures to enable large single pour of multi-span bridge decks appears to be of little value. Oklahoma Wet curing is preferred to curing compounds. Oregon Limit maximum slump. Require wind breaks during placement. Pennsylvania The pilot program included a provision that fogging apparatus be used regardless of evaporation rate. This became a problem because at times the water did not atomize and ponded on the fresh concrete creating a slurry. Rhode Island Use of fibers and shrinkage compensating admixtures. Virginia 1. Making contractor open deck to traffic quickly. This makes them add cement and therefore water, making the deck more likely to crack. 2. Emphasizing strength over durability. Wisconsin Fibers Alberta Fogging systems. Effective fogging systems are cost prohibitive and contractors typically try to utilize portable pressure washers which are ineffective and poorly implemented in the majority of applications where used. Fogging systems were specified for many years but discontinued in lieu of placement of evaporation reducers prior to implementation of continuous surface wet cure systems. Ontario Currently we have ceased use of high performance concretes in bridge decks due to problems with cracking in some decks; cracking does not occur in all decks, but reasons for cracking are not clear. Considering use of shrinkage testing to prequalify high performance and high strength mixes for use in bridge decks. Use of saturated lightweight aggregate for internal curing considered but does not appear to be practical as a standard approach. Prince Edward Island Curing compounds. 9. What is the frequency of use of the following cements in your agency’s concrete bridge decks? Material Number of Responses Never Sometimes Often Always AASHTO M 85 Type I and IA 7 4 13 9 AASHTO M 85 Type II and IIA 3 6 13 11 AASHTO M 85 Type II(MH) and II(MH)A 19 3 6 1 AASHTO M 85 Type III and IA 23 7 1 1 AASHTO M 85 Type IV 32 0 0 0 AASHTO M 85 Type V 29 2 1 0 AASHTO M 240 22 5 3 1 ASTM C1157 23 3 2 1 10. What is the frequency of use of the following supplementary cementitious materials in your agency’s concrete bridge decks? Material Number of Responses Never Sometimes Often Always Fly ash Class C 11 11 13 3 Fly ash Class F 5 11 17 6 Pozzolan Class N 26 8 2 0 Silica fume 11 16 9 5 Ground-granulated blast-furnace slag 12 10 15 1 Other 17 1 0 1 Other listed materials were metakaolin, and fly ash and lithium if reactive aggregate is used.

94 11. What is the frequency of use of the following admixtures for cast-in-place concrete bridge decks? Admixture Number of Responses Never Sometimes Often Always AASHTO M 194 Type A—Water-reducing admixtures 2 7 15 14 AASHTO M 194 Type B—Retarding admixtures 4 20 10 3 AASHTO M 194 Type C—Accelerating admixtures 19 15 2 1 AASHTO M 194 Type D—Water-reducing and retarding admixtures 5 18 11 3 AASHTO M 194 Type E—Water-reducing and accelerating admixtures 21 14 2 1 AASHTO M 194 Type F—High range water-reducing admixtures 8 12 13 5 AASHTO M 194 Type G—High range water-reducing and retarding admixtures 16 15 5 2 Corrosion inhibitors 25 11 2 1 Shrinkage-reducing admixtures 21 13 2 2 Expansive cement or components 30 8 0 0 12. What length of wet curing does your agency currently specify for cast-in-place concrete bridge decks? Number of Responses None 3 days 7 days 14 days Other 1 3 20 11 8 Other lengths of wet curing were 4, 5, 8, and 10 days. One agency reported using curing compound. 13. How is wet curing achieved? Agency Method Alaska Heavy burlap or quilted cotton blankets are most often used. Infrequently, full wetting and saturation with sprayers or perforated hoses are used. Arkansas Burlap-polyethylene mats or burlap covered with approved sheeting materials. Burlap maintained continuously and thoroughly wet for 7 days, typically with soaker hoses. Delaware Plastic, burlap, hoses Illinois Wetted cotton mats or cellulose polyethylene blankets. Iowa Curing Concrete Decks. Use burlap with sufficient water that is prewetted by fully saturating, stockpiling to drain, and covering with plastic to maintain wetness prior to placement, to prevent absorption of moisture from the concrete surface. Keep the burlap wet. 1. Place the first layer of prewetted burlap in the following manner: a. Interstate and Primary Projects. Place on the concrete within 10 minutes after final finishing. b. Other Projects. Immediately after final finishing and grooving, cover the area finished with white pigmented curing compound meeting requirements of Article 4105.05 applied at a maximum rate of 135 square feet per gallon. Place the first layer of prewetted burlap on the concrete within 30 minutes after the concrete has been finished and grooved. Burlap placement beyond 30 minutes may be allowed, up to an additional 30 minutes, if approved by the Engineer based upon environmental conditions at time of deck placement. 2. As soon as practical, but no later than 2 hours after placing the first layer, place a second layer of prewetted burlap on the deck. 3. Apply water to the burlap covering for a period of 4 calendar days. Use a pressure sprinkling system that is effective in keeping the burlap wet during the moist curing period. The system may be interrupted only to replenish the water supply, during periods of natural moisture, or during construction contiguous to the concrete being cured. The Engineer may approve interruptions for periods longer than 4 hours on the basis of the method for keeping the concrete moist. 4. Maintain continuous contact, except as noted above, between all parts of the concrete deck and the burlap during the 4 calendar day moist curing period. 5. On concrete decks placed after October 1 and prior to April 1, after 20 hours of the application of water, the Contractor may substitute the application of a moisture proof plastic film no less than 3.4 mils thick over the wet burlap in lieu of applying water. Maintain intimate contact between the surface of the concrete, the burlap, and the plastic film. Kansas Burlap, soaker hoses, plastic Massachusetts Wet burlap Michigan Burlap, soaker hose, and plastic sheeting Minnesota Pre-wetted burlap within 30 minutes, soaker hoses, white poly covering Missouri With wet mat. Plastic cover over wet burlap for curing low slump or silica fume concrete after 24 hours of continuously keeping wet. Montana Presoaked burlap, soaker hoses, plastic Nevada Soaker hoses and burlap covered in plastic or wet curing blankets. Maine Soaker hoses, wet burlap, and plastic sheets or insulated blankets Mississippi We do not wet cure.

95 Wisconsin 502.3.8.2.3 Decks (1) For structures under 100 feet in length, cure the concrete in decks, medians, and sidewalks for at least 7 days with polyethylene-coated burlap or other coated material conforming to 501.2.9. As soon as the concrete sets sufficiently to support the covering, place the coated burlap with the coated side up; or perform an initial cure of the concrete by using wetted burlap for at least 12 hours and then apply the coated burlap to a thoroughly wetted concrete surface. Place each strip or sheet of coated burlap so that it overlaps the preceding sheet by at least 12 inches. Secure the coated burlap covering in place. Ensure adequate moisture is present on the surface of the floor, wearing surfaces, or sidewalks beneath the curing material for the 7-day curing period. (2) For Structures 100 feet or greater in length, cure the concrete in decks, medians, and sidewalks by the following method. Begin curing the horizontal concrete surfaces by fogging within 15 minutes of finishing and tining. Apply the fog or fine water spray so that no water marks result and no mortar washes from the concrete surface. Keep the concrete surface continuously wet by fogging until applying the burlap strips to the finished concrete. Wet the burlap immediately after placement. During the first day, until placing the soaker hose system, keep the burlap continuously wet. Through the remainder of the curing period, keep the burlap continuously wet with soaker hoses hooked up to a continuous water source. Inspect the burlap on a daily basis to ensure that the entire surface is moist. If necessary, alter the soaker hose system as needed to ensure the entire surface is moist. Do not use white polyethylene sheeting or plastic coated burlap blankets. Continue moist curing at least 7 days. Wyoming Burlap or polyethylene sheeting continuously damp using fogging methods. Alberta Two layers of filter fabric or 1 layer of filter fabric and 1 layer of thinner fabric with perforated poly. Manitoba Blanketing and wetting Ontario Burlap presoaked for 24 hours prior to use. Soaker hoses placed on burlap to operate throughout curing period. Plastic placed over all to reduce evaporation. Fogging for silica fume concretes during placement. Prince Edward Island Contractors have a storage tank of water on site connected to a series of perforated hoses across the deck top overlaid onto filter fabric or burlap. The water runs continuously for 7 days. Saskatchewan Curing blankets and sprinklers Yukon Using soaked wet burlaps New Hampshire Wet burlap New Jersey Wet burlap and white polyethylene sheeting New York 14 day’s burlap covered constantly wet. Last 7 days curing covers permitted to replace burlap. North Dakota Burlap and water Oklahoma Fogging, followed by the application of two layers of wet burlap, wet burlap is covered with white polyethylene film and soaker hoses are used to keep the burlap wet at the end of 7 days, the curing membrane is applied. Oregon Require wind breaks when evaporation rate reaches a specified limit. Apply fog spray for all placements. Cover wet concrete with saturated wet burlap or non-woven, needle punched polypropylene fabric curing blanket within a maximum time limit. Provide soaker hoses. Place a layer of polyethylene film over the covering and soaker hoses. Pennsylvania Wetting the concrete deck and placing wet burlap all over the deck surface. Rhode Island Wet burlap with plastic or fogging South Dakota Typically, with wet burlap/curing blankets and poly sheeting. Tennessee a) place damp burlap over slab; b) apply a mist spray over the cover and thoroughly wet with a continuous soaker hose system for 120 hours. Texas Wet cotton mats covered with plastic or other wet blanket system. Must keep wet. Utah Refer to the UDOT Specifications—Structural Concrete or Contact the UDOT Materials Division Vermont Wet burlap typically Washington Fogging and burlap Agency Method 14. Does your agency specify epoxy-coated reinforcement for concrete decks? U.S. agencies only. Canadian agencies do not use epoxy-coated reinforcement. Reinforcement No. of Responses Yes No Top layer 33 5 Bottom layer 3 5 Girder reinforcement projecting into the deck 23 13 15. What types of reinforcement with metallic coatings has your agency used in cast-in-place concrete bridge decks? None: 19 agencies Zinc coated: 19 agencies Stainless steel coated: 13 agencies Other: 3 agencies but did not list the type. Explain any effect of their use on cracking.

96 State Effect California None Iowa We have only built a handful of bridge with galvanized reinforcing. Most of the bridges were built in the 1970s. Deck deterioration took longer to initiate, but deck cracking wasn’t necessarily reduced compared to a conventionally reinforced deck. Kansas None noted Maine No evidence that a reduction of cracking has resulted. Use has been for increased corrosion protection. Missouri Not aware of New Jersey None observed New Mexico Similar to epoxy coating. Rarely used. New York There is no obvious difference in cracking when metallic reinforcement is used. North Dakota Used once. No idea on effect of cracking. Pennsylvania Cracking is more of a function of the cementitious properties than rebar coating. Rhode Island Unknown Vermont We see no difference based on coating. Virginia No known affect Wyoming Zinc coated used on one bridge in the top mat only. Alberta Not measured Ontario No apparent impact; these materials were used on a very limited basis and are not currently in use. Saskatchewan No difference than black steel 16. Has your agency used solid stainless steel reinforcement in cast-in-place concrete bridge decks? Yes: 18 agencies No: 24 agencies If “Yes,” how did its use affect deck cracking? Agency Effect California No effect Colorado No data Kansas None noted Minnesota No initial change Montana One time about 16 years ago New Jersey No difference New Mexico Similar to epoxy coating. Rarely used. New York No obvious difference Oregon SS is used in coastal environments where temperature and humidity are relatively constant, so deck cracking is minimized due to these environmental conditions. Cracking is minimal minor tight cracks, less than in other portions of Oregon. South Dakota No difference in deck cracking was noted. Vermont No effect if cover is maintained. We are trying some projects to reduce cover to get reinforcement closer to the top surface of the deck when solid stainless is used. Virginia No known effect Wisconsin No effect Alberta Not measured Ontario No apparent impact. Not sure that this has been evaluated comprehensively. Saskatchewan No difference in cracking than black steel 17. Has your agency used fiber-reinforced polymer (FRP) reinforcement in cast-in-place concrete bridge decks? Yes: 17 agencies No: 25 agencies If Yes, how did its use affect deck cracking? Agency Effect California Prevents plastic shrinkage cracks and holds cracks tighter if they do form. Florida Proposed on Halls River Bridge Replacement for letting 6/15/16. Kansas None noted Maine Too early to tell. Just started to use it experimentally. Minnesota Project will be let in the summer of 2016 so no results yet. Missouri Not known New Hampshire Greatly reduced cracking Oregon Similar to SS, we use it only in coastal environments where we experience much less deck cracking. Utah GFRP Vermont Not enough data to tell. Virginia No known effect Alberta Not measured Ontario Used to limited extent in decks. Not aware of any apparent impact, but not sure how exhaustive the investigation has been. Prince Edward Island Initially there was some increase in the amount of cracking; however, as time and experience progressed, we see no net effect of cracking increase or decrease with the use of FRP bars versus black steel. Yukon It helped in preventing the deck cracking.

97 18. Has your agency used ASTM A1035 reinforcement in bridge decks based on a yield strength of 100 ksi for design? Yes: 3 agencies No: 39 agencies If “Yes,” how did its use affect deck cracking? Agency Effect Florida As of January 1, 2016, now allowed by FDOT Structures Manual. We have a bridge constructed with MMFX-II; however, it was not based on the design yield strength. Rather it was a direct replacement of conventional steel. There are spans with conventional and MMFX and both are performing similarly at this stage. See attachment for more details. Oklahoma No data available Virginia Not sure Alberta Not measured Yukon Used CSA approved amount 4. PreStreSSed concrete BeaMS (canadian participants go to question 21) 19. Does your agency use Article 5.10.10.1—Splitting Resistance of the AASHTO LRFD Bridge Design Specifications Seventh Edition to design the splitting reinforcement at the ends of beams? Yes with no modifications: 23 U.S. agencies Yes with modifications: 5 U.S. agencies No: 7 U.S. agencies If your agency has modifications or design practices to supplement Article 5.10.10.1, what are they? Agency Modification Florida Have specified areas of splitting reinforcing for a maximum bonded prestress force in standard beam shapes (See SDG 4.3.1.D). Use a minimum of 10 in. for h/4. Illinois Refer to “Page 3-214” & “Page 3-215” of our Bridge Manual, as well as Figure 29 of ABD Memo 15.2. Minnesota Vertical reinforcement H/4 is sometimes increased. To fit the required amount of steel in the ends and still allow the concrete to flow between the vertical bars. Oklahoma In order to keep cracks less than 0.012", one of our fabricators is using additional steel exceeding the requirements of 5.10.10.1, this modification is being done in the shop drawings. Pennsylvania The following shall replace A5.10.10.1. The splitting resistance of pretensioned anchorage zones provided by vertical reinforcement in the ends of pretensioned beams at the service limit state shall be taken as: Pr = fsAs (5.10.10.1-1) where: fs = stress in steel not exceeding 20 ksi As = total area of vertical reinforcement placed near the ends of the beam at maximum spacing of 3 in. End blocks shall be investigated to help in reducing splitting stresses for prestressed beams or pier caps with forces in excess of 1800 kips. Closely spaced grids for members with forces in excess of 1800 kips shall have the grid anchored. The reinforcement for the end blocks shall be shown on the shop drawings and shall be in accordance with recommendations of the anchorage fabricator. Utah Refer to the UDOT Structures Design and Detailing Manual Washington Spread bars beyond h/4 as needed 20. Does your agency use Article 5.10.10.2—Confinement Reinforcement of the AASHTO LRFD Bridge Design Specifications to design the confinement reinforcement at the ends of beams? Yes with no modifications: 29 U.S. agencies Yes with modifications: 3 U.S. agencies No: 3 U.S. agencies If your agency has modifications or design practices to supplement Article 5.10.10.2, what are they? U.S. Agency Modification Florida Use tighter spacing beam ends, and do not always extend the placement to the full 1.5d. Missouri Provide 4 pairs of reinforcement (3 spaces @ about 3 1/ in.) in the end of prestressed girders. Extend the confinement reinforcement for the full length of girders. Increase confinement reinforcement spacing where not needed. Pennsylvania The following shall supplement A5.10.10.2. For prestressed beams, additional confinement reinforcement shall extend from each end of the beam for of the span length. The additional confinement reinforcement shall not be less than No. 4 deformed bars and match with vertical stirrups with maximum spacing of 21 in. Utah Refer to the UDOT Structures Design and Detailing Manual ¹⁄³ 5. SuBStructureS 21. Does your agency use the same crack control criteria for substructures and superstructures? Yes: 28 agencies No: 11 agencies

98 If “No,” what criteria are used for substructures? Agency Criteria Florida See SDG 3.10.A vs. SDG 4.1.8. Illinois Lower minimum cementitious content, lower minimum strengths, different allowable aggregate gradations, more options for curing, and we are not looking to try SRAs or shrinkage compensating materials in substructure concrete. Iowa We follow Article 5.7.3.4 for substructures. Minnesota Exposure factor gamma sub e is different. For Slabs and Pier Caps the factor is 0.75 and for all other situations we use 1.0. Oregon We have the same criteria as those required for superstructures, except for bridge decks we have more requirements as described in questions 5 & 7. Rhode Island Mostly Mass concrete protocols. Note that many of the mix designs are used throughout. South Dakota Gamma sub “e” = 1.0 Alberta CAN/CSA S6—Canadian Highway Bridge Design Code Ontario Per Canadian Highway Bridge Design Code (CSA S6 2014) Prince Edward Island Only difference is curing period. Still a full wet cure; however, only for 3 days as opposed to 7. 22. If your agency has experienced cracking in pier caps, please describe the type of pier cap (rectangular, inverted tee, hammerhead, etc.) and type of cracking (flexure, shear, tempera- ture, etc.)? Agency Type of Pier Cap and Type of Cracking Alaska Cracking associated with over-heating of enclosures during cold weather concreting operations has occurred. California Shrinkage Colorado Shrinkage Florida 1. Hammerhead flexure—now limit 24 ksi reinforcing stress under Service III; 2. Straddle Bent Cap shear; Iowa Rectangular pier caps typically show signs of minor flexure cracking in positive and negative bending areas. Shear cracking is seldom seen. Cracking of the ends of the cap under joints is common due to corrosion in the reinforcing. Hammerhead caps seldom have flexure or shear cracking. Massachusetts Shrinkage Minnesota Rectangular temperature Missouri Rectangular pier cap. Very rare temperature crack found. Shear cracks found in a few hammerhead piers. New York Yes, occasionally NYSDOT has experienced cracking in pier caps. Most of these cracks are temperature and shrinkage related. Flexure cracks at the tops of hammerhead piers with epoxy coated bars were observed few years ago. NYSDOT is not allowing epoxy coated bars as top flexure reinforcement for hammerhead piers now. Oklahoma Cracks in new construction are very rare. Oregon Significant shear cracking has occurred in 1950s—1960s era rectangular caps and crossbeams that had short longitudinal bar development and large shear steel spacing. Pennsylvania No cracking in new designs. Rhode Island Hammerhead South Dakota Not aware of pier cap cracking Texas Shear cracking in straddle caps (inverted T and rectangular) cracking in inverted T ledge (due to older provisions that led to under-reinforcement) Wyoming Hairline flexure and shear is typical in rectangular/hammerhead pier caps. Alberta Rectangular, hammerhead, etc. Shrinkage/temperature/flexure/formwork settlement Manitoba Yes—very infrequent-solid shaft rectangular, associated with temperature. Also having cracking in shaft on some projects associated with shock; i.e., cold weather. Ontario Has not been an issue North Dakota Nothing in the last 5 years Prince Edward Island Hammer head piers. Mainly shear and temperature and/or shrinkage cracking. Saskatchewan Rectangular, temperature and shrinkage cracks. 23. If your agency has experienced cracking in columns or abutments, please describe the type of cracking (flexure, shear, temperature, etc.)? Agency Type of Cracking California Shrinkage Florida Hammerhead column flexure cracks under construction wind loading. Iowa Cracking in columns due to flexure or shear is uncommon. Cracking usually occurs from temperature induced cracks that allow the moisture to penetrate the concrete and cause more severe cracks from corrosion. Abutments normally have vertical cracks that are most likely shear related. Massachusetts Shrinkage Minnesota Abutments temperature Missouri Very rare temperature crack found.

99 Agency Type of Cracking New Hampshire We normally have 4" weep holes in our abutments 10' on center and have experienced vertical shrinkage cracking at those locations. New York NYSDOT is experiencing some shrinkage and temperature cracking on abutments and wing walls. These cracks are generally tight and structurally not significant. Oklahoma Cracks in new construction are unusual. Oregon Rare vertical cracking has occurred due to uneven settlement or foundation undermining. Pennsylvania No cracking in new designs. Rhode Island Maybe temperature South Dakota Not aware of column or abutment cracking Texas Temperature related in columns. Thermal/shrinkage in abutment backwalls. Wyoming Temperature is common. Some flexure. Alberta Shrinkage/flexure/temperature/formwork settlement Manitoba Yes—very infrequently shrinkage Ontario Some (rare) vertical cracking in wide abutments, but I do not know the details. Prince Edward Island Mainly temperature and/or shrinkage cracking Saskatchewan Longitudinal cracking matching longitudinal rebar. North Dakota Nothing in last 5 years 24. If your agency has experienced cracking in pile caps, please describe the type of cracking (flexure, shear, temperature, etc.)? Agency Type of Cracking California Shrinkage Florida Minor temperature cracking Iowa Unknown, because most pile caps are buried underground, if you are asking about footing pile caps. Massachusetts Shrinkage Missouri No New York NYSDOT use of pile caps is limited and no significant issues with cracking have been raised. Oklahoma Not aware of cracks in pile caps Pennsylvania Minor shrinkage cracking in thicker footings. Rhode Island Temperature maybe. In one case, expected to crack. Rebar used. South Dakota Not aware of pile cap cracking Texas Mostly not aware of. On very large pile caps—have seen cracking related to lack of proper curing. Wyoming Is this the same as pier caps? Alberta Shrinkage/temperature/formwork settlement Manitoba Not usually—very infrequently sometimes occurs on wide abutments or pile caps from shrinkage. Prince Edward Island Mainly temperature and/or shrinkage cracking. Saskatchewan Not known North Dakota Nothing in last 5 years 6. reSearch 25. Please list any research in progress by your agency related to concrete cracking. Agency Research in Progress Arkansas TRC 1602 Examining the Required Cement Content in Structural Concrete Florida Mitigation of Cracking in Florida Structural Concrete. - Use of Lightweight Fine Aggregate for Internal Curing and Control of Cracking in Concrete. - Macro Synthetic Fiber Reinforcement for Improved Structural Performance of Concrete Bridge Girders. This is mainly research to improve pretensioned girder end cracking through the use of fibers. Illinois Refer to ICT R27-139 (Phase I report available here; Phase II report available Fall 2016; Phase III starting Summer/Fall 2016). Iowa HRB TR-633 Investigation into Shrinkage of High Performance Concrete Used for Iowa Bridge Decks and Overlays, Phase II - Shrinkage Control & Field Investigation Kansas Evaluation of internal curing, void-based mix designs and ongoing evaluation of SCMs. Maine Maine DOT is beginning to look at non shrink additives for cracking control. New Mexico Research primarily focused on deck cracking in the 1980s and 1990s. Led to procedures listed previously. Further research in the last decade related primarily to wind breaks and fogging systems. Oklahoma ODOT FFY 2016 SP&R Item Number 2274 “Development of Concrete Mixtures to Mitigate Bridge Deck Cracking, Validated Using 3D Bridge Deck Surface Evaluations.” Note that this research is still in the very early stages. Pennsylvania A pilot program was launched in 2015 specifically for deck cracking. Some tweaks were made and a 2016 pilot project is in the works. Texas 16-337: Evaluating Long-Term Durability/Performance of Prestressed Concrete Beam with Extensive Surface Cracking 16-342: Evaluation of Structural Cracking in Concrete North Dakota Member of Crack Free Bridge Deck Pooled fund. Plan on implementing those specifications

100 Agency Research in Progress Utah Contact UDOT Research Virginia Study of decks cast using special “low cracking deck concrete” specification Wisconsin WHRP Project 0092-15-01Precast/Prestressed Concrete Bridge Girder Cracking Phase II Ontario Our agency is funding research at University of Toronto to look at evaluating the cracking potential of high performance concrete mixes. We would like to be able to prequalify high performance mixes for use in bridge deck applications, to avoid excessive cracking. Yukon Cracks on the deck top of floor beams (Pony and Through truss deck structures) 26. Please list any recommendations for future research needs related to concrete cracking. Agency Research Recommendation Alaska Specifying permissible crack widths associated with different size reinforcing bars. Florida Investigate methods for improving the end region cracking in pretensioned girders. Kansas Expansive admixtures Maine Cement- and pozzolan-based research could be useful in conjunction with shrinkage- reducing admixtures New Mexico Methods for reducing reflective cracking when partial-depth precast deck panels are employed. New York NYSDOT is more focused on implementing the findings of research into design and construction practices. Oklahoma Pulpcure—bridge deck applications, internal curing and SRA’s appear to have some potential Pennsylvania A shrinkage-reducing admixture, further reducing the shrinkage from 500 microstrains to 250. Rhode Island Some hopefully addressed by NCHRP FY2017 D-03, if accepted Utah Contact UDOT Materials Alberta Comparative study of partial depth precast concrete deck panel vs. conventional full depth cast-in-place deck cracking. Noticeable reduction in crack frequency for partial depth panel decks with same HPC concrete mix. Ontario Need more research on behavior of concrete mixes with multiple admixtures, particularly high performance and self-consolidating concretes. Basic slump and physical property tests North Dakota Deck cracking are insufficient to identify suitable mixes for use in highway applications. Need tests to quantity shrinkage and cracking potential. Further information on role of reinforcement layout on crack control (or not) is needed, for high strength concrete mixes; there has been little coordination between designers and materials experts in identifying causes of cracking. Saskatchewan How to reduce and control vertical cracks in cast in place traffic barriers. On top of a concrete deck slab. Yukon Use additional reinforcement or control joints on the center of floor beam to mitigate cracking. 27. Please list any agency research reports that document the performance in bridges with regard to control of concrete cracking and are available to be referenced in this synthesis. Case studies are of particular interest. Please provide links or upload files in Question 29. http://www.iowadot.gov/research/reports/Year/2014/fullreports/mass_concrete_ii_w_cvr2.pdf Agency Research Report Arkansas TRC 0603 Curing Practices to Reduce Plastic Shrinkage in Concrete Bridge Decks, 2011 TRC 1002 Evaluation of High Performance Curing Compounds on Freshly Poured Bridge Decks 2012 California Evaluating Proposed Concrete Specifications for the Prevention of Deck Cracking. Florida Files will be emailed separately. They are not necessarily reports that document the performance: however, they are reports that relate to research that was conducted to improve the cracking performance. Iowa Mass Concrete—http://www.intrans.iastate.edu/research/documents/research- reports/mass_concrete_i_w_cvr.pdf Kansas The University of Kansas has completed several for us: Files are available at the following, particular reports of interest include SL Report 15-3, SM Report No. 107, ODOT SPR Item Number 2231, SM Report No. 103, SM Report 94, and SM Report No. 92: http://iri.ku.edu/reports North Dakota Crack Free Bridge Deck Pooled Fund Research Final Report Oregon “The Use of Synthetic Blended Fibers to Reduce Cracking in High Performance Concrete,” SPR 500-620, Oregon State University, September 2014. “Development of Shrinkage Limits and Testing Protocols for ODOT High Performance Concrete,” SPR 728, ODOT-OSU, December 2013. Pennsylvania A report conducted by Penn State University and an interim report to FHWA is attached. South Dakota “Optimized Aggregate Gradation for Structural Concrete,” SD2002-02 http://www.sddot.com/business/research/projects/docs/SD2002_02_Final_Report.pdf. Texas FHWA/TX-12/0-6348-2 Evaluation of Alternative Materials to Control Drying-Shrinkage Cracking in Concrete Bridge Decks, Report No. 0-4098-4. Author: Kevin Folliard Utah Contact UDOT Research or visit the UDOT website for research projects Virginia Upcoming report from the Virginia Transportation Research Council Washington WSDOT report on evaluation of performance-based concrete mixes for bridge decks. Ontario I am attaching an internal report completed by MTO several years ago investigating the cracking of high performance concrete bridge decks (60 MPa, 1000 Coulomb RCP) in northern Ontario. The investigation showed a correlation between temperature of the concrete during the first 24–48 hours, and degree of cracking, with mixes that reached higher temperatures faster exhibiting more cracking. Cracking was not related specifically to mix design, since mixes with the same parameters cracked in some cases and not in others.