The methodology for defect quantification in concrete using IR thermography

Abstract

This paper presents a procedure for detecting and quantifying defects in reinforced concrete structures by using 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 possibility 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 successfully 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%.

Keywords:

• testing methodology
• defect characterization
• IR thermography
• non-destructive testing
• reinforced concrete
• active thermography techniques
• principal component thermography
• correlation operators technique

Additional information

Notes on contributors

Bojan Milovanović

Bojan MILOVANOVIĆ. PhD. Postdoctoral researcher at the University of Zagreb, Faculty of Civil Engineering, Department of materials. He is a member of 6 national and international professional bodies. He is a Level II thermographer, and licensed IR thermography instructor. In his scientific work he is dealing with the problems regarding energy efficiency, building physics, and non-destructive testing (primarily infrared thermography) and has published several papers on these topics. He is finished his PhD thesis titled “Application of Infrared Thermography for defect characterization in reinforced concrete”. He has collaborated on several domestic and EU projects: REPUBLIC MED (Retrofitting Public Spaces in Intelligent Mediterranean Cities), CROSKILLS I Build Up Skills for Croatia (CIP Intelligent Energy Europe BUILD UP Skills initiative), Eco-Sandwich – Energy Efficient, Recycled Concrete Sandwich Facade Panel (CIP Eco-Innovations), INTENSE – From Estonia till Croatia: Intelligent Energy Saving Measures for Municipal housing in Central and Eastern European countries (Intelligent Energy Europe), From Nano to Macrostructure of Concrete, Microstructure of mineral composites containing sheep’s wool. Currently, he is participating in the CROSKILLS II Build Up Skills CROatia: (IEE/13/BWI/722/SI2.680179), CA EPBD IV project as well as SEEDPass – South East Europe strategic partnership in vocational education and training in Passive House Design for nearly zero energy buildings development. He is a member of publishing board of the “CrSNDT Journal” and “International Journal of Energy Efficiency in Buildings”. Mr. Milovanović published more than 70 scientific papers as an author or co-author. His research interests are IR thermography, building physics, energy efficiency and concrete technology.

Ivana Banjad Pečur

Ivana BANJAD PEČUR. Prof., Head of the Department of materials and Head of Materials Research Chair and professor in the Department of materials at the University of Zagreb, Faculty of Civil Engineering. Prof. Banjad Pečur has experience in national scientific and technological projects (Energy efficiency, Special types of concrete, Prefabricated construction using MEPS concrete) and international scientific projects (CROSKILLS – Build Up skills Croatia, ECO-SANDWICH Energy Efficient, Recycled Concrete Sandwich Facade Panel, LIFE project CONWAS – Development of sustainable construction and demolition waste management system for Croatia”). She was participating in the project CA EPBD III – Concerted Action supporting transposition and implementation of Directive 2002/91/EC of the European Parliament and of the Council and its proposed recast, as expert on building physics and implementation of measures of improvement. Currently, she is participating in the CA EPBD IV project as well as SEEDPass – South East Europe strategic partnership in vocational education and training in Passive House Design for nearly zero energy buildings development. Prof. Banjad Pečur is project coordinator for CROSKILLS I, CROSKILLS II and ECO-SANDWICH projects. Prof. Banjad Pečur published more than 70 scientific papers as an author or co-author. Her research interests are IR thermography, energy efficiency, concrete technology and non-destructive testing.

Nina Štirmer

Nina ŠTIRMER. Prof., Head of Materials Technology Chair and Professor at the University of Zagreb, Faculty of Civil Engineering, Department of Materials. Previously she was Head of Laboratory of materials and coordinating national scientific project “From nano to macro structure of concrete”. She was senior expert in CIP Eco-innovation project RUCONBAR – Rubberized concrete noise barriers, CIP IEE project “Croskills I” and CIP Eco Innovation project “Eco-sandwich”). She was actively participating in EUREKA project “Industrial floors” and LIFE project CONWAS – Development of sustainable construction and demolition waste management system for Croatia”. Currently she is an associate on the EU projects Anagennisi (FP7), CROSKILLS II, and acting as the Vice Dean for Financial Management at the University of Zagreb, Faculty of Civil Engineering. Prof. Štirmer published more than 80 scientific papers as an author or co-author. Her research interests are concrete technology and resource efficiency, recycled materials.