Concrete Technology for Transportation Applications (2019)

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102 Florida Department of Transportation: Temperature Control of Mass Concrete Criteria to Be Considered as Mass Concrete ACI 301, “Specifications for Structural Concrete for Buildings,” states that a concrete place- ment should be designated as mass concrete when the maximum temperatures and temperature differences must be controlled due to factors including the content and type of cementitious materials, environment surrounding placement, and minimum dimension of placement. To put this statement in context, ACI 301 contends that, in general, a placement of structural con- crete with a “minimum dimension equal to or greater than 4 feet should be considered mass concrete.” ACI 301 also indicates that the minimum dimension could be reduced by concrete placements that produce higher rates of heat generation at early ages, such as those that contain Type III cement, accelerating admixtures, or have high contents of cementitious materials. The Florida DOT Structures Design Guidelines (https://www.fdot.gov/structures/structures manual/currentrelease/structuresmanual.shtm) require that, for all bridge components except drilled shafts and segmental superstructure pier and expansion joint segments, “when the minimum dimension of the concrete exceeds 3 feet and the ratio of volume of concrete to the surface area is greater than 1 foot, provide for Mass Concrete.” Mass Concrete Control Plan Content Florida DOT Standard Specifications for Road and Bridge Construction (January 2018), Section 346-3.3 states that When mass concrete is designated in the Contract Documents, use a Specialty Engineer to develop and administer a Mass Concrete Control Plan (MCCP). Develop the MCCP in accordance with Section 207 of the ACI Manual of Concrete Practice to ensure concrete core temperatures for any mass concrete element do not exceed the • maximum allowable core temperature of 180°F and . . . • maximum allowable temperature differential of 35°F [between the element core and surface]. Submit the MCCP to the Engineer for approval at least 14 days prior to the first anticipated mass concrete placement. Ensure the MCCP includes and fully describes the following: 1. Concrete mix design proportions, 2. Casting procedures, 3. Insulating systems, 4. Type and placement of temperature measuring and recording devices, 5. Analysis of anticipated thermal developments for the various mass concrete elements for all anticipated ambient temperature ranges, C H A P T E R 4 Case Examples of State Practices

Case Examples of State Practices 103 6. Names and qualifications of all designees who will inspect the installation of and record the output of temperature measuring devices, and who will implement temperature control measures directed by the Specialty Engineer, 7. Measures to prevent thermal shock, and 8. Active cooling measures (if used). The Specialty Engineer or approved designee shall: • Inspect and approve installation of temperature measuring devices • Verify that the process for recording temperature readings is effective for first placement of each size and type of mass component • Be available for immediate consultation during monitoring period of any mass concrete element • Record temperature measuring device readings at intervals no greater than six hours, beginning at the completion of concrete placement and continuing until decreasing core temperatures and temperature differentials are confirmed • Leave temperature control mechanisms in place until the concrete core temperature is within 50°F of the ambient temperature • Within three days of the completion of temperature monitoring, submit a report to the Engineer which includes all temperature readings, temperature differentials, data logger summary sheets and the maxi- mum core temperature and temperature differentials for each mass concrete element. Mass Concrete Mix Designs Mass concrete is normally Class IV 5,500 psi, with a minimum total cementitious material content of 658 lb/yd3, and a maximum water–cement ratio of 0.41. Mixtures typically contain fly ash (18%–50% by weight), slag (50%–70%), or a combination of fly ash (10%–20%) and slag (50%–60%) as partial replacements for portland cement. Remediation Procedures When Temperature Limits Are Exceeded If either the maximum allowable core temperature or temperature differential of any mass concrete element is exceeded: • Implement immediate corrective action as directed by Specialty Engineer. • Approval of the MCCP shall be revoked, and no mass concrete elements can be placed until a revised MCCP has been approved by the Engineer. • Submit an Engineering Analysis Scope that addresses the structural integrity and durability of any mass concrete element that is not cast in compliance with the approved MCCP or that exceeds the allowable core temperature or temperature differential. • Submit all analyses and test results requested by the Engineer for any noncompliant mass concrete element to the satisfaction of the Engineer. Exceptions to the Temperature Monitoring Requirements of Mass Concrete Reduced Monitoring. When there are multiple mass elements that are similar, reduced monitoring can be initiated by the following procedure: • Submit a Reduced Monitoring request to the Engineer at least 14 days prior to the requested date of reduced monitoring; • If approved, the Specialty Engineer shall monitor the initial element of the group of similar elements; and • If the performance of the initial element meets all the requirements of the MCCP, then the remainder of the similar elements may not be monitored if they meet all of the following requirements: – All elements have the same least cross-sectional dimension, – All elements have the same concrete mix design,

104 Concrete Technology for Transportation Applications – All elements have the same insulation R value and active cooling measures (if used), and – Ambient temperatures during concrete placement for all elements is within −10°F or +5°F of the ambient temperature during placement of the initial element. No Monitoring. Mass concrete control provisions are not required for drilled shafts sup- porting sign, signal, lighting, or intelligent transportation (ITS) structures. At the contractor’s option, instrumentation and temperature measuring may be omitted for any mass concrete substructure element meeting all of the following requirements: • Minimum cross-sectional dimension of 6 feet or less, • Insulation R value of at least 2.5 provided for at least 72 hours following the completion of concrete placement, • Environmental classification of the concrete element is Slightly Aggressive or Moderately Aggressive, and • The concrete mix design meets the mass concrete proportioning requirements of Section 346-2.3, and the total cementitious content of the concrete mix design is 750 lb/yd3 or less. Problems with the Use of Reduced Monitoring and No Monitoring. Section 346 states that for Reduced Monitoring it is necessary to: • Install temperature measuring devices for all mass concrete elements. • Resume the recording of temperature monitoring device output for all elements if “directed by the Engineer.” However, in the field, the following have become common practices: • For “Reduced Monitoring,” only the first element is being instrumented. • For “No Monitoring,” MCCPs are not being submitted. These procedures have been in place since January 2016 and have resulted in very few structures being instrumented. Two of the most important means of reducing the potential for thermal cracking involve limiting the core–surface temperature differential to 35°F until the core temperature has cooled sufficiently, and keeping forms and thermal control measures in place until the core–ambient temperature differential is ≤50°F. Limiting the core tempera- ture and core–surface temperature differential to specified values cannot be done without recording and monitoring temperatures. Potential Future Changes to Mass Concrete Specifications • Instrumentation of mass concrete elements that are not being monitored under the Reduced Monitoring provision will need to be enforced. • Research, which will likely lead to modifications of specifications, is needed to answer the following questions: – What are safe maximum temperatures for each combination of portland cement and supplemental cementitious materials (SCMs)? – Are particular portland cement-SCM combinations more susceptible to cracking? – What should the maximum core-surface and core-ambient temperature differentials (gradients) be? – How should maximum concrete temperatures at placement be determined to mitigate cracking? – Should analyses using finite element modeling programs replace the use of physical and compositional characteristics to indicate likelihood of mass concrete behavior and how to mitigate?

Case Examples of State Practices 105 Illinois Department of Transportation: Reducing Concrete Shrinkage in Bridge Decks Introduction The Illinois DOT has for at least the last 20 years been working to mitigate the early age transverse cracking that is a typical problem on its bridge decks. A variety of high-performance concrete mix designs were tried in the late 1990s. However, many of these mixes incorporated silica fume, which seemed to exacerbate the cracking problem. Thus, in 2010, research work started on mixture- or materials-based methods for reducing bridge deck cracking. Earlier efforts of this research identified shrinkage-compensating mineral additives (Type K and Type G additive products) and shrinkage-reducing chemical admixtures as potentially viable technolo- gies. Research has proceeded now into a third, and final, phase wherein the scope has expanded to include internal curing with prewetted lightweight fine aggregate, as well as considering the potential benefits of using the identified mitigation technologies in combination (e.g., Type K additive with internal curing). Additionally, a component of this ongoing research has been trial implementation. As of the writing of this report, there have been six field trials using special provisions drafted for each of the three mitigation strategies. Two bridge decks each have been constructed using Type K mineral additive, SRA, or internal curing, and each has been successful in reducing early age cracking in bridge decks. Research on Additives, Admixtures, and Curing Shrinkage-Compensating Additives Shrinkage-compensating mineral additives were developed to compensate for the shrink- age characteristics of ordinary portland cement by causing the concrete to expand and induce compressive stress during hydration. This induced compressive stress essentially self-stresses the concrete to counteract tensile stresses, such as those due to shrinkage. For Type K mineral additives, the expansion is achieved by ettringite forming as a result of the reaction of gypsum and calcium sulfoaluminate (CSA). On the other hand, the expansive properties of Type G mineral additives are based on the formation of calcium hydroxide crystals resulting from the reaction of calcium oxide and water. While both Type K and Type G additives have been investigated as part of this research, the Illinois DOT has focused primarily on Type K, or CSA, cement products, since the second phase. Shrinkage-Reducing Admixtures SRAs are liquid chemical admixtures added to concrete like other typical liquid admixtures. SRAs can help mitigate shrinkage-related cracking by reducing the surface tension of the water in concrete. This is because as concrete dries, the capillary stresses induced by its pore water seeking escape are directly proportional to the pore water’s surface tension. Thus, as surface tension decreases, capillary stresses decrease as well, leading to lower shrinkage strains within the concrete. Furthermore, Sant et al. (222) concluded that SRAs may also enhance concrete’s durability by reducing its sorptivity and moisture diffusivity, thereby reducing chloride and other deleterious ion absorption and migration. Internal Curing In addition to mineral additives and chemical admixtures, the Illinois DOT began investigat- ing internal curing to help address concrete shrinkage. Internal curing is achieved by substituting a portion of the conventional fine aggregate volume of a concrete mix with prewetted light- weight fine aggregate made from expanded shale, clay, slate, or slag. The prewetted lightweight aggregate (LWA) is able to provide additional water to the concrete because its internal relative

106 Concrete Technology for Transportation Applications humidity decreases during hydration or drying. Thus, by reducing moisture gradients within the concrete, internal curing can alleviate capillary stresses and associated shrinkage strains. This can be particularly beneficial to concretes placed with water–cement ratios less than 0.42, such as Illinois DOT’s bridge decks, by hydrating more of the cementitious material without the potential consequences of batching at higher water–cement ratios. Conclusions from First Two Phases Conclusions of the first two phases of the research included the following: • Replacing 15% portland cement with Type K resulted in minimal shrinkage strain after 100 days. • Including Class F fly ash increased the restrained expansion of Type K concrete specimens, whereas silica fume resulted in a decrease in the extent of expansion. • Slump loss was rapid in Type K concrete, and expansion was reduced with extended mixing time; both factors need to be considered for long haul times. • Including Type K reduced the total heat of hydration of paste specimens. • Compressive strengths of Type K concretes at 28 days were found to be similar to or higher than the compressive strengths of plain concrete. Including Class C or F fly ash resulted in lower 28-day strengths, whereas silica fume increased 28-day strengths. • High dosages of SRA lengthened the time to cracking in the ring test, but also seem to have reduced compressive strength. • Shrinkage rate after expansion of Type K concrete is comparable to that of conventional concrete, whereas the shrinkage rate of SRA-dosed concrete is less than that of conventional concrete. • Even when the same amount of internal curing water is provided, the type and source of LWA can have different effects on autogenous and drying shrinkage of mortar mixtures, which is believed to be a result of the LWA’s desorption properties, gradation, and modulus. • Increasing the amount of internal curing water, whether by increasing the replacement rate of LWA or by increasing the initial moisture content of LWA, reduced autogenous shrinkage. • In a sealed condition, the total shrinkage of mortar mixtures decreased as the replacement with LWA increased. • External curing is still necessary. When no curing method is applied, LWA was not beneficial in reducing drying shrinkage of mortar specimens. Practical lessons learned from trial implementation of these shrinkage mitigation technolo- gies are as follows: • Class C fly ash may reduce or be incompatible with Type K mineral additives. The period and extent of expansion may be reduced due to the Class C fly ash reacting with the ye’elimite component of the Type K additive. Early results suggest that adding a small amount of gypsum to the system will counteract this problem. • In a ready-mix operation using bagged Type K mineral additives, they appear best incor- porated into the batching process as a slurry. Otherwise, if adding it via bags to a ready-mix truck, there is the risk that the product will clump or ball. These balls may not be noticeable during the placing and finishing of the concrete, but because they are less dense than the con- crete, they can rise to the surface of the deck, resulting in pockets of unhydrated product that will blister the surface when exposed to water, for example, during wet curing. • Type K mineral additives require a large amount of water. It is important to ensure that enough water is added to completely hydrate the Type K additive; otherwise, unhydrated material will attempt to expand once exposed to water, resulting in essentially a delayed ettringite formation distress.

Case Examples of State Practices 107 • Working closely with the SRA manufacturer’s technical representative is advisable. For example, if freeze-thaw deterioration is a concern, there are some SRAs that can make it more difficult to achieve a stable, satisfactory air void system. • Sufficient drain-down time helps prevent issues when batching prewetted lightweight fine aggregate; otherwise, the material can be sticky and may “bridge” in bins or hoppers not equipped with vibrators. For example, Illinois DOT’s initial specification required a mini- mum 48-hour wetting period followed by 12 to 15 hours of drain down; the current specifica- tion requires at least 72 hours of wetting and 20 to 24 hours of drain down. • When discussing internal curing with DOT personnel and contractors, it is necessary to emphasize that internal curing is not a substitute for conventional external curing practices. Internal curing supplements external curing, which can only provide water to the near-surface concrete. Internal curing helps provide water to the entire cross section of the concrete during curing. For example, in laboratory tests, internal curing did not significantly change the drying shrinkage characteristics of concrete without some external method to prevent moisture loss. Developing Shrinkage Mitigation Strategies The goal of the final phase of this research was to develop shrinkage mitigation strate- gies and performance criteria for statewide implementation. Doing so will require providing robust options that account for issues such as material availability, local experience and exper- tise, material incompatibilities, and so on. Additionally, there is the potential optimization of concrete mixes using a combination of strategies. For example, because Type K mineral additives require so much water, it may be possible to provide water via prewetted LWA instead of increasing the mix water, foregoing consequences typical of concretes with high water–concrete ratios (e.g., lower strength, increased permeability). So far, results have been promising, showing that internal curing increases the early age expansion of Type K mortar specimens, partly due to a reduction in bulk modulus of elasticity (from the LWA portion), but also due to increased Type K hydration. Meanwhile, adding SRA to internally cured mixes reduced drying shrinkage considerably, made the mixture more volumetrically stable and, at a water–concrete ratio of 0.34, reduced autogenous shrinkage. For more information, please see the research reports from the first and second phases of this research available for download from the Illinois Center for Transportation (223, 224). Missouri Department of Transportation: Precast Concrete Pavement Demonstration Project on I-57—Lessons Learned Introduction In 2005 the Missouri DOT constructed a precast posttensioned concrete pavement (PPCP) on I-57 in the southeast part of the state. The project was initiated by funding support from the FHWA. The existing pavement was a badly distressed 8-in. (20-cm) jointed reinforced con- crete pavement (JRCP) with 61.5 ft (18.75 m) joint spacing that was 46 years old at the time of the PPCP construction. Extensive pumping and slab failures were prevalent. The local terrain was flat and consisted of sandy-silt soils. Daily traffic was approximately 18,000 with 30% trucks. Construction The PPCP panels were to replace a 1,000-ft tangent section of the old JRCP. Both ends of the PPCP would have new cast-in-place 15-ft jointed plain concrete pavement (JPCP) transitions. The proposed dimensions of the PPCP panels were 38 ft (11.58 m) wide [including two 12-ft

108 Concrete Technology for Transportation Applications (3.65-m) lanes, 4-ft (1.22-m) inside shoulder, and 10-ft (3-m) outside shoulder] and 10 ft (3 m) long. Panels were lightly pretensioned across the width with No. 4 rebar to resist cracking during transit from the precast plant. To simplify the installation of the panels, a 4-in. (10-cm) permeable asphalt-treated base (PATB) course was constructed as a subbase beneath the PPCP. The PATB was designed with a flat profile, rather than the standard center crown profile, which would allow the bottom of the panels to also be flat. The PATB was placed on a 4-in. (10-cm) dense graded aggregate base. To maintain a minimum 8-in. (20-cm) structural thickness across both driving lanes and provide a 2% surface cross slope for drainage, the panel thickness at the centerline crown had to be 10.875 in. (27.63 cm) thick. The 2% cross slope also resulted in reducing the thickness of the inside and outside shoulders to 7 in. (17.8 cm) and 5.625 in. (14.3 cm), respectively. The panels were divided into four 250-ft (76.2-m) posttensioned sections, called “super slabs,” which comprised 24 base panels. Two additional joint panels were installed at the two ends of each super slab. Joint panels were designed as two 38-ft × 5-ft (11.6-m × 1.5-m) panels. The panels were connected by dowel bars spaced every 12 in. (30 cm). The joint panels had post- tensioning pockets on 2-ft centers through which 5/8-in. (1.6-cm) steel strands were threaded and passed through the length of the super slab. Strands were posttensioned in the pockets after all panels were in place. Challenges The perceived advantage to precast pavement technology is speed in construction. Posttension- ing panels, however, added a layer of complexity that extended the construction period to 4 weeks. The contractor was not familiar with the technology to begin with. In addition, he also encountered other unexpected difficulties. The first challenge was that the joint panels were locked and could not slide open, even when subjected to small hydraulic jacks. It is suspected that the dowel bars might have been mis- aligned during fabrication. This led to a succession of other problems. Since the contractor had to forego opening a specified gap in the joint panel to account for future anticipated expansion, based on the ambient temperature range, they instead left small gaps between the base panels in the super slab. The intent was that the joint panels would finally be forced to open during posttensioning and the gaps between the base panels would then close. The base panels could not close cleanly though, because the epoxy material that was brushed on their vertical faces, which was supposed to provide a waterproof seal after posttensioning, dried and created uneven texture before the base panels could be tensioned together. Another related issue was that the panels were drifting off course, whether from the uneven gaps between panels or some other reason. To compensate and bring the panels back in alignment, the con- tractor inserted several small wooden wedges in the joints, thus creating more opportunity for water to infiltrate after posttensioning. During the actual posttensioning, the joint panels did indeed finally open; however, one of the joints did not open properly and ruptured the concrete in tension failure a few inches away from the joint. This led to a chronic maintenance problem to keep the poured joint header material intact. The joint header and silicone filler in the other expansion joints required periodic maintenance to a lesser degree. Filling the grout ducts after posttensioning required an unexpected quantity of grout. The first three ducts in one super slab used as much grout as was anticipated for all the strand ducts in the four super slabs. It is likely that grout escaped through the slightly open base panel joints and infiltrated the PATB.

Case Examples of State Practices 109 Performance Within several months after construction, hairline horizontal cracks appeared in some panels. The thinking was that they were present since fabrication because shrinkage cracks had not opened enough to become visible until later. It is highly doubtful that these cracks could have formed after posttensioning. The University of Missouri at Columbia had a research contract to instrument several panels with strain gauges and monitor the sensors during fabrication and after installation and opening to traffic. An important finding was that the tensile strains developed during the curing process were two orders of magnitude higher than the barely perceptible 1–2 macrostrains measured from truck loading. This was a strong indication that the posttensioned panels were virtually assured of never experiencing critical load-induced stresses. Conclusion Overall, the PPCP is a success in terms of providing more than adequate structural support on an Interstate highway with heavy truck traffic. However, the high cost of the time of installation and posttensioning and the periodic maintenance required at expansion joints conspire to make this an unlikely design option for future pavement replacement. Nonstressed modular precast pavement panels seem to be a much more practical option. New York State Department of Transportation: Implementation of Performance-Engineered Mixtures Introduction PEM specifications are different from prescriptive specifications in that the latter com- municate how a material or product is to be formulated and constructed, whereas perfor- mance specifications communicate the desired characteristics of the material or product. PEM specifications allow for greater partnership between the owner (the DOTs) and the contrac- tor to allow greater opportunities for innovation and improved long-term performance. The New York State DOT, like many other state DOTs, is moving to the use of PEM to take advan- tage of newer technologies to progress projects in a way that provides greater performance, often at reduced cost. The availability of resources has decreased over the years making it imper- ative to develop and use more effective strategies for progressing projects. Using materials more effectively with the ability to perform less direct inspection while still achieving and ensuring quality is a key part of PEM implementation. Background The New York State DOT began using performance specifications many years ago. Initially the performance requirements were focused on early strength gain or for specialty concrete mixtures such as lightweight concrete or SCCs. Later, pavement mixtures were modified to allow the use of well-graded aggregates to reduce cement content and to use lower water– cement ratios. These changes achieved the strength and durability characteristics of the mix- tures while providing more economical mixtures and maintaining workability. Technological advances in materials testing capabilities have allowed further advancement of performance specifications. The key is having the appropriate tools in place to provide QA for concrete. Moving forward from the above, the use of both the surface resistivity (SR) and the super air meter (SAM) represents those tools. By specifying certain resistivity requirements for different applications (deck versus substructure versus pavement . . .) the quality of the concrete

110 Concrete Technology for Transportation Applications can be better controlled. SR is directly affected by water content, pozzolan content, and, to a lesser extent, by aggregate gradation. A quality mixture for a structural application will need to have a typical water–cement ratio (0.40–0.42), pozzolan content of at least 20% (if not more for ASR concerns), and well-graded aggregate (likely blended aggregate or No. 3 size). By specify- ing resistivity requirements, along with the above-listed requirements, we can be assured of the quality of the concrete for the application. Lesser SR requirements can be specified for other ele- ments that have less risk and/or do not need to be as high a quality to perform for the expected service life. The SAM, which is an enhanced Type B pressure meter, can measure not only total air content, but can also assess the quality of the air void structure, similar to a linear traverse. Having an adequately dispersed air void system provides the assurance toward long-term dura- bility. The biggest benefit of SAM use is that information can be determined while the concrete is still plastic, and so adjustments to subsequent batches can be made as needed. Specification The New York State DOT has evaluated a number of standard concrete mixtures using SR and SAM, comparing the performance characteristics to newer PEMs. The PEMs typically exceed the performance of existing department mixtures. Through the use of special specifi- cations, PEMs are being used on a number of high-profile projects where characteristics are desired to achieve longer service life and improved durability, or where special performance is necessary. Because of the success with these special specifications, the New York State DOT is now in the process of replacing standard specifications using prescriptive concrete mix- tures with PEM specifications containing performance provisions. The proposed specification changes include: • Contractors/producers develop QC plan for mixture design and plant production. DOT performs QA with random audits at batching facilities. • Approved-list materials are still required to be used (why disregard what we know already works), but unique materials may be considered for use on a case-by-case basis, based on past successful experience demonstrated by the contractor. • Contractors/producers would develop and provide PCC mixtures that meet the performance criteria defined in specifications for a given use or application. • Performance requirements include – Compressive strength (4,000 psi minimum), – Aggregate gradation to meet specific project applications, – Air content, – Aggregate friction requirement for pavements and bridge decks, – ASR mitigation requirements, – SAM use to determine freeze-thaw durability requirements for flatwork applications, – Concrete permeability requirements determined by use of surface resistivity or RCP tests. This requirement ensures that the water–cement ratio is kept in check and that pozzolans are properly used as needed. The criteria vary depending on application, for example, decks have the highest requirements. Implementation This initiative to implement PEMs for different types of concrete has been ongoing for a number of years. The biggest challenge toward implementation is the migration toward and acceptance of change. The prescriptive approach has been in place for many decades, and people are used to how it works and what the normal expectations are. Getting people to understand the PEM concept in order to become willing participants in trial projects has been difficult. Therefore, extensive training is necessary.

Case Examples of State Practices 111 With the performance approach, the contractor/producer now assumes the responsibility of the production and performance of the concrete mixture. With this transfer of risk comes an increased material cost to the owner. This increased cost, however, can be misunderstood at times as it is generally balanced out by the reduced staffing and resource needs of the department and frequently tied to improved and longer expected performance of the concrete. A significant fiscal investment is also necessary in order to procure the needed new SR and SAM testing tools, combined with becoming familiar with their use from trial work. The collection of data associ- ated with locally available materials is also important in order to ensure the appropriate selection of specification criteria. Key to Success The key to success is familiarizing people with the concept and developing a proper under- standing of how it is intended to work. Identification of pilot project applications is important to be able to learn from their advantages and shortcomings and apply this knowledge to further specification or policy implementation. Tennessee Department of Transportation: Barriers and Solutions to Concrete Technology Implementation Introduction The Tennessee DOT has experienced many barriers to implementing new concrete technologies. Highway agencies, such as the Tennessee DOT, are tasked with being good stewards of taxpayers’ money, and so cost is always an important issue but is not the most critical factor in the decision to implement new technologies. Typically, new technologies and materials are promoted to either improve efficiency with time savings or create better quality products with a longer service life, and so the associated cost is just one of the factors that would be a part of the decision-making process to implement the technology on state projects. Examples of Barriers and Solutions An important potential barrier to technology implementation is the lack of sufficient train- ing to use the technology. Training was an important issue when SCC became increasingly popular in transportation projects. At that time, there were not many training options for the agency inspectors to be certified to test SCC, since ACI had not yet developed a training class or included the SCC tests in the ACI Concrete Field-Testing Technician Grade I course (https:// www.concrete.org/certification/certificationprograms.aspx?m=details&pgm=Field%20Concrete %20Testing&cert=Concrete%20Field%20Testing%20Technician%20-%20Grade%20I). The Tennessee DOT’s approach to overcoming this barrier was to develop a training course as part of the scope of work of an ongoing Tennessee DOT-funded research project. The course was developed to help technicians understand potential uses of and best practices with SCC as well as to focus on how to perform the ASTM/AASHTO test methods for SCC mixes. Initially, the agency developed and provided pilot classes throughout the Tennessee DOT regions. Once the training was completed, the course was refined and adopted as part of the department’s Concrete Field-Testing Technician Course (https://www.tn.gov/tdot/materials-and-tests/ field-operations/training.html). Resistance to change is another one of the most prevalent obstacles to implementing new technologies. This resistance does not always come from industry, but also internally within the

112 Concrete Technology for Transportation Applications DOT. One effective method that the Tennessee DOT has found to be useful in overcoming this resistance is by having a good working relationship with the individual industry liaison groups. The industry liaison groups are effective in communicating to their members the information on potential program changes that the DOT is considering and getting feedback from the affected industry. This feedback is valuable for the DOT. It allows full understanding of how changes in the program might affect the industry, including any negative consequences of the changes. This may lead to more communications and possible modifications. Also, through this good working relationship, the industry has often proposed new technologies or materials for Tennessee DOT consideration, which effectively eliminates one barrier of resistance to change. Concluding Remarks Internally within the Tennessee DOT, a myriad of methods and tools are used to inform the staff of the potential program changes to alleviate internal resistance to change. For internal awareness and education, the agency utilizes webinars and presentations by industry or product experts. The department considers actual demonstration of the proposed new technology or material as the most effective educational and training tool for both agency engineers and industry professionals to assess the true potential of the technology or material and promote wide acceptance.