I want ppt on infrared thermography in concrete engg ...

infrared thermography in civil engineering ppt

Abstract

Infrared thermography is becoming ever more popular in civil engineering/architecture mainly due to its noncontact character which includes two great advantages. On one side, it prevents the object, under inspection, from any alteration and this is worthwhile especially in the presence of precious works of art. On the other side, the personnel operate in a remote manner far away from any hazard and this complies well with safety at work regulations. What is more, it offers the possibility to quickly inspect large surfaces such as the entire facade of a building. This paper would be an overview of the use of infrared thermography in the architectural and civil engineering field. First, some basic testing procedures are described, and then some key examples are presented owing to both laboratory tests and applications in situ spanning from civil habitations to works of art and archaeological sites.

1. Introduction

Infrared thermography (IRT) is being used in an ever more broad number of application fields and for many different purposes; indeed, any process, which is temperature dependent, may benefit from the use of an infrared device. In other words, an infrared imaging device should be considered a precious ally to consult for diagnostics and preventative purposes, for the understanding of complex fluid dynamics phenomena, or for material characterization and procedures assessment which can help improve the design and fabrication of products. Infrared thermography may accompany the entire life of a product, since it may be used to control the manufacturing process, to nondestructively assess the final product integrity, and to monitor the component in-service.

The first use of infrared thermography, as a nondestructive testing technique, dates back to the beginning of the last century [1, 2], but it was only recently accepted amongst standardized techniques. Initially, IRT suffered from perplexities and incomprehension mainly because of difficulties in the interpretation of thermograms. It received renewed attention starting from the 1980s when the importance of heat transfer mechanisms [3, 4] in image interpretation was understood. Now, infrared thermography is a mature technique and is becoming ever more attractive in an ever more increasing number of application fields. This has also led to a proliferation of infrared devices, which differ in weight, dimensions, shape, performance, and costs, to fulfil desires of a multitude of users in a vast variety of applications [5]. In fact, an infrared imaging system can be now tailored for specific requirements and it can be advantageously exploited for process control and maintenance planning without production stops and with consequent money saving. Of course, complete exploitation of infrared thermography requires understanding of basic theory and application of standard procedures.

Of relevant interest is the application of an infrared imaging device in architecture and civil engineering after Building Regulations for Conservation of Fuel and Energy (2007). However, infrared thermography can be used also to discover defects in buildings envelope, to monitor reinforcing steel in concrete, to detect moisture inside building walls, and so forth [6–8].

It is known that masonry structures deteriorate over time mainly due to natural forces of decay, due to thermal stresses, and due to water infiltration; the main degradation effects include variations in concrete compaction and voiding, spalling or microcracking in masonry, and reinforcement deterioration and this may be of great concern if the structure belongs to the cultural heritage. Indeed, IRT represents a valuable tool for nondestructive evaluation of architectonic structures and artworks because it is capable of giving indication about most of the degradation sources of artworks and buildings of both historical interest and civil use. In particular, by choosing the most adequate thermographic technique, it is possible to monitor the conservation state of artworks in time and to detect the presence of many types of defects (e.g., voids, cracks, disbonding, etc.) in different types of materials [9, 10]. It is possible to inspect either a large surface, such as the facade of a palace, or a very small surface of only few square millimetres. The main advantages of infrared thermography when dealing with precious artworks may be summarized in three words: noncontact, noninvasive, and two dimensional.

Long-term conservation of artworks involves periodic inspection to evaluate existing conditions, to discover deficiencies at an incipient stage, and to plan restoration before catastrophic failure occurs. In this context, infrared thermography (IRT), as a remote imaging system, represents a powerful tool to be used for quick periodic inspection. The images can be stored in a digital format and a history of the material degradation can be easily examined and visualized as well as compared to a previous situation by retrieval of archived images. It is known that IRT has some limitations when dealing with deep and low thermal resistance defects, but it has proved to still be useful in conjunction with high-depth techniques [11–13].

This work would be an overview of some of the applications of infrared thermography to the architectural field performed at the Aerospace Engineering Section of the Department of Industrial Engineering, University of Naples Federico II, to which the author belongs. The results shown herein come from laboratory tests as well as in situ inspection of civil buildings and of important artworks such as the mosaic of the Battle of Issus in the Archaeological Museum of Naples and frescoes in the Villa Imperiale in Pompeii.