Advances in sensing technologies, as well as signal interpretation and imaging methods have made nondestructive testing (NDT) a rapidly growing discipline for measuring the condition and properties of transportation materials and structures. Nondestructive testing tools are being developed that provide more comprehensive and accurate information about in-situ conditions that can be used at high speeds without traffic interruption. Construction quality control and assurance is also a major factor in the life of the infrastructure and these tools have the ability to provide complete coverage and rapid feedback. Deploying technologies that can measure quality during construction is the best way to improve quality. This requires rapid, field-ready technology. Other technologies improve both construction and design. An example of is the use of surface characteristic tools that improve ride, friction and noise through improved design and construction. Managing the aging infrastructure is another major issue facing transportation agencies. As part of the bridge inspection procedure, assessments such as advanced cracking and deterioration in concrete bridge decks are made to develop condition and sufficiency ratings. These qualitative assessments need to be upgraded to quantitative NDT methods that are capable of measuring the type, location and severity of distresses. Improvements in the quality and completeness of the infrastructure will improve the design, construction quality and maintenance decisions. Some examples of emerging NDT technologies are step-frequency ground penetrating radar, ultrasonic array imaging, acoustic emission, and continuous compaction control. Transportation agencies have had mixed success with NDT. Some of the barriers for agencies to implement NDT technologies include: -Inadequate information: understanding when a technology is ready for deployment and what its capabilities are. NDT developers also may lack an understanding of the need and the scope of conditions. -Insufficient validation: capabilities of the technology are overstated leading to unrealistic expectations and subsequent skepticism of its feasibility. Verifications conducted in labs under ideal conditions do not account for the complexities and variations found in the field. -Lack of a holistic approach: each method has been applied on its own merit. A combination of methods using different principles may lead to a more comprehensive evaluation. -Lack of end user tools, training, and implementation protocol: having user friendly data analysis, integration tools, training and support available as well as documented procedures and protocols for in-situ testing required for complete implementation -Lack of effective tools: To save user and construction costs, states need high speed NDT devices to rapidly evaluate conditions without any or with minimal lane closures. Step-Frequency GPR has the potential for this application. States also need NDT devices for construction QC/QA that can provide immediate feedback for performance measures such as density, IRI, etc.

The overall objective of this pooled fund is to implement nondestructive testing tools so that agencies can improve the design, construction and maintenance of the transportation infrastructure (pavements, bridges, structures). This pooled fund will select technologies at stages of research, development and implementation, and advance them to deployment. Activities will include: • Conduct research and development on new NDT technologies so that they are fully developed and ready for implementation. • Enhance data analysis and visualization tools as needed to facilitate the data analysis and interpretation process. • Explore, validate and verify NDT devices and methods through initial laboratory testing and complete field trials. • Calibrate equipment and provide demonstrations and training on production devices and tools. • Verify new devices proposed by vendors to assure they are feasible for deployment.

It is anticipated that the pooled fund will focus on those technologies that are most relevant to its participants. Two technologies that are of interest to MnDOT and FHWA are the Step-Frequency GPR (3D-GPR) and the Ultrasonic Pulse-Echo Tomography (MIRA) tools. Both these technologies are being developed by FHWA and are being used in field tests that show great promise. This project will further develop and demonstrate these technologies, in addition to other technologies as determined by the contributing partners. It is anticipated that several specific research/development/implementation projects will be initiated during the course of this pooled fund study. The specific technologies, topics and activities of each project will be determined by the pooled fund participants at selected times during the life of the project. The example work plan for 3D-GPR and MIRA applications is as follows: • Validated applications are o pavement structure information (layer thicknesses), o detect changes in material properties such as asphalt mix stripping, bonded PCC overlay or partial depth repair bond assessment, o dowel, tie bar and continuous reinforcement position determination o finding objects and detect drainage problems, The pooled fund will conduct pilot demonstration and implementation projects at participating state sites. These will provide blind test evaluations of 3D-GPR and MIRA versus forensic analysis. They will document the case histories, refine process for doing pavement evaluation and develop user guidelines. Software suitable for state agencies to perform data analysis may also be developed. • For applications that need further validation such as: o Pavement and bridge deck assessment for stripping or delamination, o Asphalt density for quality assurance (GPR); o PCC joint and crack deterioration evaluation o Materials degradation evaluation The pooled fund will conduct field evaluations for these applications and compare results to ground-truth/data from other methods. Algorithms for objective data analysis will be developed and verified with blind tests. Analysis of results, identification of any needed software development and or processes, recommendations for next steps including deployment will be performed. If application is deemed ready for implementation, the above steps will be taken. The FHWA will actively participate in this project by making the 3D-GPR equipment available along with their contractor for the GPR data collection and data interpretation support. Other contractors may be required for developing processes and documentation. The University of Minnesota has MIRA equipment and is working on evaluation for FHWA. Additional equipment for states may be purchased through the pooled fund for testing and implementation. Each specific activity will be initiated with a workshop to discuss needs, identify and prioritize potential projects and develop a detailed work plan.

The recommended participation level is $20,000 per year for 3 years. Additional funding may be committed if approved projects and activities warrant.