1,334 research outputs found

    Non-destructive evaluation of concrete using a capacitive imaging technique : preliminary modelling and experiments

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    This paper describes the application of capacitive imaging to the inspection of concrete. A two-dimensional finite-element method was employed to model the electric field distribution from capacitive imaging probe, and how it interacts with concrete samples. Physical experiments with prototype capacitive imaging probes were also carried out. The proof-of-concept results indicated that the capacitive imaging technique could be used to detect cracks on the surface of concrete samples, as well as sub-surface air voids and steel reinforcement bars

    Comprehensive Bridge Deck Deterioration Mapping of Nine Bridges by Nondestructive Evaluation Technologies Final Report, January 2011

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    The primary objective of this research was to demonstrate the benefits of NDT technologies for effectively detecting and characterizing deterioration in bridge decks. In particular, the objectives were to demonstrate the capabilities of ground-penetrating radar (GPR) and impact echo (IE), and to evaluate and describe the condition of nine bridge decks proposed by Iowa DOT. The first part of the report provides a detailed review of the most important deterioration processes in concrete decks, followed by a discussion of the five NDT technologies utilized in this project. In addition to GPR and IE methods, three other technologies were utilized, namely: half-cell (HC) potential, electrical resistivity (ER), and ultrasonic surface waves (USW) method. The review includes a description of the principles of operation, field implementation, data analysis, and interpretation; information regarding their advantages and limitations in bridge deck evaluations and condition monitoring are also implicitly provided.. The second part of the report provides descriptions and bridge deck evaluation results from the nine bridges. The results of the NDT surveys are described in terms of condition assessment maps and are compared with the observations obtained from the recovered cores or conducted bridge deck rehabilitation. Results from this study confirm that the used technologies can provide detailed and accurate information about a certain type of deterioration, electrochemical environment, or defect. However, they also show that a comprehensive condition assessment of bridge decks can be achieved only through a complementary use of multiple technologies at this stage,. Recommendations are provided for the optimum implementation of NDT technologies for the condition assessment and monitoring of bridge decks

    Corrosion Assessment Methods in Reinforced Cement Concrete

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    Worldwide huge amount was spent on infrastructure development projects, in which a major part is spent on demolishing deteriorated structures due to their reduction in serviceability due to various external factors. This may be attained by preventing reinforced cement concrete (RC) structures from factors that affect serviceability such as corrosion. The research community is developing various techniques to predict corrosion in RC structures to prevent the structure in the initial stages by carrying out maintenance work instead of going for the reconstruction of deteriorated structures. The corrosion of RC structures was mainly caused by chloride ions penetrating the structure or by carbonation. This coefficient can be used to predict the rate of corrosion in concrete. Electrochemical measurement, Eddy current, Half-cell potential measurement, etc., are the experimental techniques to forecast the corrosion rate in concrete reviewed. Recently various software’s like Life 365, Thermos calc, Concrete Compass, etc., were developed to predict the corrosion rate in RC structures. This research paper reviews the effectiveness of the application of software to predict corrosion rate in RC structures by reviewing previous research works to identify an accurate method to be followed

    Evaluation of concrete corrosion using EMI sensor

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    Reinforced Concrete (RC) is globally used to make the building structure strong and more durable. Civil and structural engineers face major challenges as concrete structures deteriorate and get weaker. Recent development in field of assessing and monitoring the health condition of the building structure have shown that corrosion in concrete reinforcement is the cause of failure. Thus, there lies a better research opportunity in the field of monitoring and assessing health condition of the building structure. This paper presents an innovative technique of initial monitoring of corrosion in concrete structures using Non-Destruction Evaluation (NDE). An early monitoring sensor was developed using Faradays law of electromagnetic induction (EMI) principle, multiple loop coil (MLC) acts a sensor which has a receiver and transmitter coil. The placement of the two coils on concrete structures measures the potential difference which later is used to analyse the level of corrosion

    Assessment of Deteriorated Structural Concrete to Provide Durable Repairs

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    Most of the structural elements on Kentucky bridges are made of reinforced concrete. Many of these elements deteriorate as a result of corrosion of the reinforcing steel caused by carbonation and — primarily — applications of chlorides by the Kentucky Transportation Cabinet (KYTC). Corrosion of reinforcing steel is reviewed along with assessment procedures that leverage nondestructive evaluation (NDE) methods and related laboratory and field tests. Several maintenance procedures are discussed, including the application of sealers and coatings, patch and major concrete repairs, and electrochemical methods. Incorporating NDE and test results into maintenance procedure selection is discussed. Recommendations are provided on expanding application of NDE and tests as this can enable better maintenance decision making related to corrosion of reinforced concrete

    Evaluation of Steel Rebar in Concrete Using Electromagnetic Method

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    The corrosion of steel reinforcing bar (rebar) is the leading cause of deterioration of concrete. In Japan, many railway bridges were built 40 years ago. It is necessary to develop easy-operation method to evaluate the corrosion of steel rebar. A project about the corrosion evaluation of steel rebar was started in 2015. In this project, we have two objectives: one is to evaluate the depth and the diameter of steel rebar in concrete; another is to evaluate the corrosion of steel rebar in concrete. We developed electromagnetic methods to do nondestructive evaluation of the steel reinforcing bar (rebar) in concrete. Using two probes and lower excitation frequencies of 3.8 and 4.2 kHz, the depth and the diameter of the steel reinforcing bar can be evaluated. Using higher excitation frequency of about 80 kHz, and the X, Y signals of the lock-in amplifier, where the X signal is the same phase signal with the AC excitation magnetic field and Y signal is the 90° phase different signal with the AC excitation magnetic field, we could evaluate the corrosion of steel rebar. A compact system with low power consumption of 0.5 W was developed, and we also did some field experiments using this system
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