Abstract
This paper presents a procedure for detecting and quantifying defects in reinforced concrete structures by us-ing the method of active infrared thermography (IRT). For quantitative analysis, a methodology of thermal stimulation of concrete specimens and post-processing of the gathered data was developed. Presented methodology uses principles of step heating (SH) thermography, pulsed phase (PPT) thermography, principal component thermography (PCT) and correlation operators technique. A short descriptions of the post-processing methods used in the research is also provided in the paper. All three post-processing methods i.e. PPT, PCT and correlation operators technique have shown the pos-sibility to enhance the defect detection in concrete structures in comparison to raw thermograms. According to the data accessible to the authors, in presented research, correlation operators and PCT post-processing techniques are being suc-cessfully used for the first time for defect detection within concrete structures. The results of the research clearly show the possibility of using active IRT for the detection and assessment of defect depth (quantification) in reinforced concrete structures with the measurement error within 10%.
Highlights
Over the past few years, many techniques have been developed in order to evaluate the state of reinforced concrete (RC) structures, to detect the location and the extent of construction defects or damaged zones in a non-destructive (NDT) way (Malhotra, Carino 2004; Gorzelańczyk et al 2013; Lee, Kalos 2015)
Contribution of this paper is that principal component thermography (PCT) and correlation operators’ techniques are alongside Pulsed phase thermography (PPT) adopted for the use in the field of RC structures, within the newly developed methodology for defect characterization in concrete using active infrared thermography (IRT)
Results of the research using the method of active IRT presented in this paper are such that the following can be concluded
Summary
Over the past few years, many techniques have been developed in order to evaluate the state of reinforced concrete (RC) structures, to detect the location and the extent of construction defects or damaged zones in a non-destructive (NDT) way (Malhotra, Carino 2004; Gorzelańczyk et al 2013; Lee, Kalos 2015). The properties of material make it difficult to image concrete, which has low thermal conductivity and is thermally inert This means that it takes a lot of energy to manipulate temperature change of RC structures, i.e. initiate heat flow in order to use active IRT to detect and/or characterise defects. Weiser et al (2010) are careful with the conclusions and state only that increased reliability for quantitative prediction of data is possible It was noticed by the authors during literature review that there is no established methodology for determining defect’s size by using active IRT in the field of concrete structures. The possibility of active IRT application to RC, development of testing methodology and analysis procedures that enable defect quantification is being presented in this paper
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