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Non-destructive-detection of chlorides and moisture in multi-layer- structural elements such as concrete bridge decks using high frequency electromagnetic waves

English title Non-destructive-detection of chlorides and moisture in multi-layer- structural elements such as concrete bridge decks using high frequency electromagnetic waves
Applicant Hugenschmidt Johannes
Number 137517
Funding scheme Project funding (Div. I-III)
Research institution Mobilität, Energie und Umwelt Empa
Institution of higher education Swiss Federal Laboratories for Materials Science and Technology - EMPA
Main discipline Civil Engineering
Start/End 01.10.2011 - 30.04.2012
Approved amount 32'349.00
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Keywords (5)

Concrete; Corrosion; Non-destructive testing; Electromagnetic waves; Inversion

Lay Summary (English)

Lead
Lay summary

Corrosion of reinforcement bars (re-bar) in structural elements made of reinforced concrete is a major problem in countries where salt is applied to roads for de-icing and in marine environments. Concrete structures are periodically inspected in order to monitor possible damage caused by chloride-induced corrosion of the reinforcement. However, certain structural elements such as bridge decks covered with asphalt pavements are not accessible for visual inspection and probing is limited. As a result, the planning of rehabilitation of bridge decks is usually based on a small number of probes. Consequently, the condition of bridge decks can only be assessed with low certainty. Therefore, a method that enables the conditions of reinforced concrete elements covered with asphalt pavements or other layers to be studied is desirable.

Work carried out by Empa and other institutions suggests the suitability of ground-penetrating-radar as a means to inspect chloride contamination of bridge decks. Different approaches have been suggested and several studies have been carried out on real bridges. However, results are far from being uniform. Some authors found that radar results compare favourably with results obtained by other methods, whereas others came to the conclusion that the results do not fit very well.

This project aims at a profound investigation of the influence of various parameters on the propagation of electromagnetic waves in concrete and their exploitation, in particular, for the non-destructive detection of chloride ions in concrete. The project will be carried out within the framework of a PhD-thesis and will involve three partners (Empa, EPFL, Forschungszentrum Jülich) to ensure that all relevant aspects are covered and supported by specialists.

This proposal aims at a unique combination of theoretical aspects, modeling, inversion, laboratory experiments and a field test. This will answer several questions currently discussed by the scientific community and foster the application of innovative and beneficial inspection methods in civil engineering.

Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Chlorides and moisture assessment in concrete by GPR full waveform inversion
Kalogeropoulos et al. (2011), Chlorides and moisture assessment in concrete by GPR full waveform inversion, in Near Surface Geophysics, 9, 277-286.

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
14th International Conference on Ground Penetrating Radar 04.06.2012 Shanghai, China
Jahrestagung der Deutschen Geophysikalischen Gesellschaft 05.03.2012 Hamburg, Germany
IWAGPR 2011 22.06.2011 Aachen, Germany
IWAGPR2009 Granada 27.05.2009 Granada, Spain


Associated projects

Number Title Start Funding scheme
119797 Non-destructive-detection of chlorides and moisture in multi-layer-structural elements such as concrete bridge decks using high frequency electromagnetic waves 01.05.2008 Project funding (Div. I-III)

Abstract

Corrosion of reinforcement bars (re-bar) in structural elements made of reinforced concrete is a major problem in countries where salt is applied to roads for de-icing and in marine environments. Concrete structures are periodically inspected in order to monitor possible damage caused by chloride-induced corrosion of the reinforcement. However, certain structural elements such as bridge decks covered with asphalt pavements are not accessible for visual inspection and probing is limited. As a result, the planning of rehabilitation of bridge decks is usually based on a small number of probes. Consequently, the condition of bridge decks can only be assessed with low certainty. Therefore, a method that enables the conditions of reinforced concrete elements covered with asphalt pavements or other layers to be studied is desirable.Work carried out by Empa and other institutions suggests the suitability of ground-penetrating-radar as a means to inspect chloride contamination of bridge decks. Different approaches have been suggested and several studies have been carried out on real bridges. However, results are far from being uniform. Some authors found that radar results compare favourably with results obtained by other methods, whereas others came to the conclusion that the results do not fit very well. This project aims at a profound investigation of the influence of various parameters on the propa-gation of electromagnetic waves in concrete and their exploitation, in particular, for the non-destructive detection of chloride ions in concrete. The project will be carried out within the framework of a PhD-thesis and will involve three partners (Empa, EPFL, Forschungszentrum Jülich) to ensure that all relevant aspects are covered and supported by specialists.This proposal aims at a unique combination of theoretical aspects, modeling, inversion, laboratory experiments and a field test. This will answer several questions currently discussed by the scien-tific community and foster the application of innovative and beneficial inspection methods in civil engineering.This follow-on proposal aims at the completion of the project No 200021-119797/1 and the PhD thesis of Alexis Kalogeropoulos. This follow-up proposal is necessary because, although the project progressed well and all experiments are performed, the elaborate inversions and interpretations are not yet finished and a completion within the original timetable is not feasible. Therefore, the timetable and the milestones were updated. Recent time-lapse inversion results show that the ob-tained data are of high quality and the completion of the project is now scheduled for April 2012. The first results of this project were recently published and the invitation to present these results at the EGU (European Geosciences Union) 2011 General Assembly indicates that the obtained re-sults are well received by the scientific community.
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