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5C h a p t e r 1 Society is more dependent than ever on transportation for its economic vitality and quality of life. Highways are the fore- most of all transportation modes. As our dependency on infrastructure is growing, the engineered components of transportation infrastructure are aging, deteriorating, and exhausting their capacity to meet the ever-expanding opera- tional demands. Ensuring operational and structural safety and security of the transportation infrastructure represents a paramount task that requires a fundamental change in the way we plan, design, build, and operate our transportation infrastructure. This task can only be effectively addressed through broad political and public support and the integra- tion of talents in diverse areas. These areas are financing, planning, asset management, design, construction, materials, inspection, and so forth. With this broad challenge identified, the second Strate- gic Highway Research Program (SHRP 2) has gathered and deployed the intellectual, experiential, and financial resources necessary to answer the questions about highway safety, renewal, travel-time reliability, and capacity. Methods must be identified to rapidly rebuild the infrastructure system with long-lasting facilities. Renewal of our highway system has become especially challenging because much of the aging infrastructure is in heavily congested highway corridors. Therefore, minimizing traffic disruptions during highway renewal projects is a paramount goal. In addition, develop- ing and implementing the means for the rapid and accurate inspection and performance monitoring of highways is of the essence, in order for the safety and durability experiences of the past to be avoided. Bridges can and should be treated as critical nodes in the greater highway system. Developing and implementing the means for rapid rebuilding, quick and reliable inspection, and performance monitoring are even more critical than for most other components of the transportation network. This is especially true for bridge decks. They deteriorate faster than other bridge components and their inspection and rehabilita- tion require traffic interruption. Providing the means for their rapid and accurate condition assessment and performance monitoring will lead to (1) more effective decision making, (2) better allocation of financial resources to renew and reha- bilitate bridge decks, and (3) reduced frequency and duration of traffic interruption caused by slow and ineffective inspec- tion and monitoring procedures. Nondestructive testing (NDT) and nondestructive evalua- tion (NDE) provide engineers and bridge owners with the ability to rapidly and effectively inspect and monitor our aging infrastructure. Data collected from the NDT of bridge decks can complement other information in the search for a better understanding of their life-cycle costs and deteriora- tion mechanisms. Also, NDT can evaluate the effectiveness of preservation techniques at various stages of the aging pro- cess, and, most important, it can prevent the premature and unexpected failure of bridge decks. The ultimate goal of this project is to develop documents and resources that will motivate and enable transportation agencies to incorporate bridge deck NDT and NDE techniques into their inspection procedures and doctrine. Achieving this goal will ultimately contribute to the broader goals of the SHRP 2 Renewal Program, which is creating a reliable and optimum bridge asset management system by transportation agencies (Figure 1.1). To accomplish the project goals, the overall work was divided into several main activities. The work was initiated with a thor- ough literature search of the main deterioration types in bridge decks and NDT technologies available or under development for their detection. The literature search resulted in the retrieval of more than 1,000 reference materials. The promising tech- nologies were categorized, graded, and ranked from the per- spectives of speed, accuracy, precision, ease of use, and other performance parameters of importance for bridge deck evalu- ation. The ranking of NDT technologies was the basis for their inclusion in the validation testing and evaluation of their generic features. Background
6To independently evaluate the performance of each of these technologies in detecting bridge deck deterioration, a valida- tion program was designed and conducted in two phases: the laboratory and field validation testing. The laboratory valida- tion testing provided a controlled environment in which the specimen deterioration and defect parameters were known in advance and could be controlled. The performance factors of highest importance during the laboratory validation were the technologiesâ accuracy and precision. The field validation enabled testing under actual, production-level conditions. Therefore, the parameters of highest importance in the field validation were the speed of data collection and analysis, ease of use, precision, and cost. A number of teams from industry and academia participated in the validation testing and dem- onstrated the application and performance of NDT technol- ogies. Several technologies were implemented by multiple participants. The analysis of the performance of NDT technologies was done on the basis of the results of the validation testing and records made by the project team. The technologies were com- pared with respect to the detection of a particular deterioration type. In the case in which a technology was represented by mult- iple participants, that technology was also evaluated to identify the best practices in data collection, and data analysis and inter- pretation. The results of these analyses were the bases for the identification of generic features of the NDT technologies and the development of recommendations for their practical implementation. Finally, the information obtained about the technologies from the literature search and the performance from the validation testing was synthesized in an electronic repository on NDT technologies for bridge deck deterioration. The organization of the report is as follows. The common deterioration types and consequential defects in concrete bridge decks are discussed in Chapter 2. The many forms of deterioration of highest importance have been summarized into four general deterioration and defect types: (1) reinforce- ment corrosion, (2) delamination, (3) vertical cracking, and (4) concrete degradation. Chapter 3 provides a discussion regarding the most promising NDT technologies for the evalu- ation of concrete decks. A summary of the criteria and method- ology used to evaluate the NDT techniques is provided in Chapter 4. Selection of the test beds for validation testing and activities related to the field and laboratory validation testing are described in Chapter 5. Chapter 6 focuses on the analysis and presentation of the results from the laboratory and field validation testing. The results are primarily categorized based on the ability of a given technique to detect a certain deterio- ration type. The grading and ranking of the technologies from the perspectives of speed, accuracy, precision, ease of use, and cost are described in Chapter 7. Chapter 8 describes the electronic repository, the NDToolbox, developed for practi- tioners as one of the major products of SHRP 2 Renewal Proj- ect R06A. Finally, concluding remarks and recommendations for future work are presented in Chapter 9. NDT Technology Ranking Test Bed Selection Validation Testing Recommendations Electronic Resource Final Report Improved Knowledge on NDT for Bridge Decks and Foundation for Better Asset Management Project Initiation Literature Search Panel Review Phase II Work Plan Figure 1.1. Project contribution to longer-lasting and more economically managed bridges.
