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This paper discusses research to develop ultrasonic methods for materials characterization of an innovative new material known as Reactive Powder Concrete (RPC). Also known as Ultra-high performance concrete (UHPC), this relatively new material has been proposed for the construction of civil structures. UHPC mix designs typically include no aggregates larger than sand, and include steel fibers 0.2 mm in diameter and 12 mm in length. These steel fibers increase the strength and toughness of the UHPC significantly relative to more traditional concretes. Compressive strengths of 200 to 800 MPa have been achieved with UHPC, compared with maximum compressive strength of 50 to 100 MPa for more traditional concrete materials. Young’s modulus of 50 to 60 GPa are common for UHPC. However, the curing methods employed have a significant influence on the strength and modulus of UHPC. This paper reports on the development of ultrasonic methods for monitoring the elastic properties of UHPC under a series of curing scenarios. Ultrasonic velocity measurements are used to estimate the bulk elastic modulus of UHPC and results are compared with traditional, destructive methods. Measurements of shear moduli and Poisson's ratio based on ultrasonic velocity are also reported. The potential for the development of quality control techniques for the future implementation of UHPC is discussed.

Reliable health monitoring, including nondestructive evaluation, is an essential part of the feedback and monitoring system for infrastructures. The goal of this paper is to provide a summary of recent research activities that will act as a catalyst to expand interest in the development of new health monitoring technologies. The paper describes the motivation for developing innovative tools for monitoring the health of the nation's infrastructure. An overview of initiatives sponsored by the National Science Foundation to develop new technologies is presented. The paper includes a review of state-of-the-art stress-wave methods for the evaluation of structural materials and pavements at National Institute of Standards and Technology. Finally, efforts at the Federal Highway Administration to develop new technologies for the assessment of the nearly 500,000 bridges along the nation's roads and highways are described.

The NDE Validation Center is a national resource for the independent and quantitative evaluation of existing and emerging NDE techniques. The resources of the NDE Validation Center are available to federal and state agencies, the academic community, and industry. The NDE Validation Center is designed to perform critical evaluations of NDE technologies and to provide a source of information and guidance to users and developers of NDE systems. This paper describes the resources available at the Center and the initial efforts to validate the visual inspection of highway bridges. Efforts to evaluate various NDE methods for the inspection of bridge hanger pins are also described.