KEYWORDS: Bridges, Nondestructive evaluation, Robotics, Robotic systems, General packet radio service, Global Positioning System, Inspection, Corrosion, Cameras, Data fusion
More economical management of bridges can be achieved through early problem detection and mitigation. The paper describes development and implementation of two fully automated (robotic) systems for nondestructive evaluation (NDE) and minimally invasive rehabilitation of concrete bridge decks. The NDE system named RABIT was developed with the support from Federal Highway Administration (FHWA). It implements multiple NDE technologies, namely: electrical resistivity (ER), impact echo (IE), ground-penetrating radar (GPR), and ultrasonic surface waves (USW). In addition, the system utilizes advanced vision to substitute traditional visual inspection. The RABIT system collects data at significantly higher speeds than it is done using traditional NDE equipment. The associated platform for the enhanced interpretation of condition assessment in concrete bridge decks utilizes data integration, fusion, and deterioration and defect visualization. The interpretation and visualization platform specifically addresses data integration and fusion from the four NDE technologies. The data visualization platform facilitates an intuitive presentation of the main deterioration due to: corrosion, delamination, and concrete degradation, by integrating NDE survey results and high resolution deck surface imaging. The rehabilitation robotic system was developed with the support from National Institute of Standards and Technology-Technology Innovation Program (NIST-TIP). The system utilizes advanced robotics and novel materials to repair problems in concrete decks, primarily early stage delamination and internal cracking, using a minimally invasive approach. Since both systems use global positioning systems for navigation, some of the current efforts concentrate on their coordination for the most effective joint evaluation and rehabilitation.
Results of an experimental evaluation of nano/micro inorganic composites are presented in this paper. Alkali alumino
silicates matrices reinforced with nano/micro fibers were used to repair (glue) fractured concrete prisms and test them in
three point bending. Further, shear strength of matrices were also obtained using push-up tests. The variables evaluated
were mix composition, temperature and specimen size. It is observed that flexural tensile strength of 1000 psi can be
achieved from the developed matrices. In some instances when repaired broken prisms were tested, the failure occurred
by creation of a new fracture surface. The developed matrices had the fluidity to fill very thin delamination, which can
be pumped to reach delamination through small drilled holes. The results show that the compositions obtained in this
study have excellent potential for application involving the repair of delamination.
Results related to the development of an inorganic matrix that is suitable for filling narrow cracks and thin delaminations
on bridge decks are presented in this paper. Almost all the repair materials currently available for these types of repairs
are organic polymer based matrices. These matrices create a discontinuity in the modulus of elasticity and water
permeability. These discontinuities result in the failure of repairs within about five years. The matrix used in the current
investigation has a modulus of elasticity and permeability characteristics that are similar to the concrete used in the
bridge decks. The primary properties investigated were: bonding to cracked surfaces, flow characteristics, ease of
application, and mechanical characteristics. This paper discusses these properties, matrix performance and matrix
viability for use in automated nondestructive robotic delivery system to fill delaminations and narrow/hairline crack in
bridge decks.
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