application of infrared thermography to the non-destructive testing of

Application of infrared thermography to the non-destructive testing

of concrete and masonry bridges

M.R. Clark, D.M. McCann, M.C. Forde*

Department of Civil and Environmental Engineering, School of Engineering and Electronics, University of Edinburgh,

The King’s Buildings, Edinburgh EH9 3JN, UK

Abstract

Within recent years there has been an increase in the use of NDT methods to detect defects and anomalies in various civil engineering

structures. Infrared thermography, which has been successfully used in the USA in civil engineering applications, is being increasingly

applied in the UK as an NDT technique. For example, the technique is now included in the Building Regulations for the assessment of

thermal insulation for all new non-domestic buildings from April 2002.

One of the perceived limitations of infrared thermography is that in temperate climates it is too cold to use this technique since there is

rarely the extreme solar exposure that has enabled the successful use of thermography to detect render debonding and concrete spalling

utilising solar heating. However, with the advancements in modern technology it is now possible to detect smaller changes in temperature

(down to 0.08 8C). This paper shows that even with the low ambient temperatures experienced in Europe it is possible to use infrared

thermography to identify correctly known areas of delamination in a concrete bridge structure and also to investigate the internal structure of

a masonry bridge.

q 2003 Published by Elsevier Science Ltd.

Keywords: Infrared thermography; Concrete; Masonry; Non-destructive testing and evaluation

1. Introduction

Most materials absorb infrared radiation over a wide

range of wavelengths, causing an increase in their

temperature. All objects with a temperature greater than

absolute zero emit infrared energy, and even glowing

objects usually emit far more infrared energy than visible

radiation. Thermal imaging is a technique for converting a

thermal radiation pattern, which is invisible to the human

eye, into a visual image. To achieve this, an infrared camera

is used to measure and image the emitted infrared radiation

from an object. Since this radiation is dependent upon the

object surface temperature, it makes it possible for the

camera to calculate and display this temperature. However,

radiation measured by the camera does not only depend on

the temperature of the object, but also its emissivity and its

absorption by the atmosphere. Further radiation (e.g.

reflected from the sun) may be introduced by the

surroundings, which may be reflected on the object.

Infrared thermography and impulse radar have been used

together on a number of occasions in the civil engineering

industry for different applications—concrete structures [1]

and on highway bridges in the USA [2]. Weil [3–5] has

shown that bridges, highway and airport pavement have

been tested with both infrared and radar finding a variety of

faults ranging from cracks on airport pavements to

delaminations on concrete bridges.

The technique of infrared thermography has been

successfully applied in a number of other areas; e.g. to

measure the conductive heat loss of infants in the medical

industry [6], in the quality assessment and design of

semiconductors [7], in the printing industry to determine

when the ink is dry [8], in concrete structures in India [9],

identification of buried mineshafts [10], identification of

canal seepage [11] as well as various other civil engineering

applications [12]. As well as many different applications of

infrared thermography there are many different methods of

using thermography; e.g. one-dimensional heat-flux sensing

(which the majority of applications utilise), the quasi-steady

technique and measuring heat transfer in wind tunnels [13].

In a number of cases, infrared thermography has been

used in collaboration with other techniques and has proved

successful. An example of this case is described in Ref. [14],

where infrared thermography was used with digital image

processing and fibre optic microscopy to assess and evaluate

weathering damage on the Medieval City of Rhodes.

0963-8695/03/$ - see front matter q 2003 Published by Elsevier Science Ltd.

PII: S0 96 3 -8 69 5 (0 2) 00 0 60 -9

NDT&E International 36 (2003) 265–275

www.elsevier.com/locate/ndteint

* Corresponding author. Tel.: þ44-131-650-5721; fax: þ44-131-452-

8596.

E-mail address: [email protected] (M.C. Forde).

http://www.elsevier.com/locate/ndteint

Another example involved infrared thermography, electrical

resistivity sounding and borehole drilling to determine the

seepage of a canal in Nebraska [11]. Infrared thermography,

acoustic imaging, radiography tomography and GPR have

been used together to determine the location and depth of

various anomalies in concrete structures [1]. While Washer

[2] states that radar and infrared thermography can be used

together to identify cracks in highway bridges in the USA,

and that infrared is a useful tool to test areas, which the radar

cannot reach. In the USA the D4788 standard [15] states the

appropriate methodology to conduct an infrared survey of

bridge decks. Various works have been undertaken to

quantify infrared images. Offermann, Bissieux and Beau-

doin [16] have done this by statistical methods.

Infrared thermography is one of many NDT techniques

available to the engineer for the non-destructive testing of

concrete and masonry bridges. It is important to appreciate

the potential applications of the techniques in comparison to

other alternatives and a comparison is made between the

various methods in Table 1.

2. Theoretical considerations

Infrared radiation is the region of the electromagnetic

spectrum between visible light and microwaves, containing

radiation with wavelengths ranging from 0.75 to 10 mm,

Fig. 1. This infrared region is often further subdivided into

arbitrary sub-regions as shown in Table 2.

It can be shown theoretically that peak radiation from a

target at room temperature of 300 K occurs at a wavelength

of 10 mm. Given that bridges in the field may be monitored

at lower temperatures than room temperature, it can be seen

that a long wavelength camera is required for structural

surveys on bridges. This equates with the long wave or far

infrared zone shown in Fig. 1 or Table 1. The short

Table 1

NDT methods for the investigation of concrete and masonry bridges

Defect NDT technique Advantage/disadvantage Relative cost

Concrete Delamination or near surface honeycombing Infrared Non-contact Medium to check

entire structureRemote monitoring

No lane possession

Coin-tap Contact required High to check

entire structureDirect access

Lane possession

Voided tendon duct Infrared Not applicable Not applicable

Radar Plastic ducts only Medium

Infrared Plastic and metallic ducts Medium

Masonry Near surface defect or feature Infrared Non-contact Medium

Remote monitoring

No lane possession

Radar Contact required Medium to high

Direct access

Lane possession

Deep defect or target Infrared Not applicable Not applicable

Radar Contact required Medium

Direct access

Lane possession

Fig. 1. The electromagnetic spectrum (based on Agema Infrared Systems (1997)).

M.R. Clark et al. / NDT&E International 36 (2003) 265–275266

wavelength camera is more applicable to a test environment

with high temperature differences, Table 3.

Long wave cameras are able to detect small temperature

differences. The camera captures the thermal information

and relays it through the PC card interface to the laptop

computer for data storage and processing. By measuring the

emitted infrared radiation from an object this camera can

measure differences in temperature down to 0.08 8C.

Radiation is a function of an object’s surface temperature,

which makes it possible for the camera to calculate and

display the temperature. The radiation measured by the

camera does not depend only on the object surface

temperature but is also a function of the emissivity.

Emissivity is a measure of the efficiency of a surface to

act as a radiator. The equation for the radiation of an object

according to the Stefan–Boltzmann equation is given in

Refs. [13,18,19], as follows:

E ¼ esT4 ð1Þ

where E is the radiation (W/m2), T is the temperature (K), s

is the Stefan–Boltzmann constant (5.67&1028 W/m2 K4)

and e is the emissivity.

Other potential problems can occur when the object

reflects radiation originating from the surroundings. Atmos-

pheric absorption of radiation will also affect the measured

temperature.

There are three methods of heat transfer, conduction,

convection and radiation. An infrared camera is only able to

record the amount of radiated heat from an object. The rate

of heat transfer through an object, which is dominated by

convection and conduction depending on the object’s

material, determines how much energy can be radiated at

the surface. One of the most important factors of each

material when talking about heat transfer is the heat capacity

of the material.

3. Practical considerations

3.1. Methodology

Thermal imagers offer an excellent means of making a

qualitative determination of the temperature of a surface,

but absolute temperature measurement is fraught with

difficulties. This depends on many variables, such as the

temperature of the surrounding materials, the atmospheric

temperature, the ambient temperature, the weather, the

object properties (i.e. the rate of conductivity, convection,

the thermal heat capacity), stress-induced temperature

change and absorption of infrared radiation. Consideration

needs to be given to the fact that outdoors many factors alter

the surface temperature of the object under investigation.

The weather can have a major effect as sunlight may

increase the temperature, wind may decrease the tempera-

ture of an object. Rain, which will lower the temperature of

an object through both conductivity and evaporation, will

also cause a change to the emissivity. However, any factor

which highlights changes in temperature actually helps

identify anomalies and features.

The advantages of using a thermal imager to measure the

surface temperature are: remote sensing, two-dimensional

data acquisition, rapid response, non-contact, high resol-

ution, large temperature range, post-processing versatility

and portability. The use of thermal imaging to detect heat

loss from a house is shown in Fig. 2.

3.2. Advantages of thermography

† Remote sensing 1. No direct contact is required between

the camera and the object under investigation. Camera

and object separation can range from a few millimetres to

several kilometres thus allowing measurements to be

Table 2

Infrared sub-regions

Sub-region Wavelength (mm)

Near infrared 0.75–3

Middle infrared 3–6

Far infrared 6–15

Extreme 15–100

Table 3

Choice of infrared camera wavelength

Test environment Example Camera wavelength

High temperature

difference

High voltage electrical

environment

Short

Concrete pavement in

hot desert climate,

e.g. Arizona/Nevada

Short

Low temperature

difference

Concrete or masonry

bridge in the UK

LongFig. 2. An infrared survey of a home can be used to highlight areas of

excessive heat loss (Agema Infrared Systems [17]).

M.R. Clark et al. / NDT&E International 36 (2003) 265–275 267

made identifying potentially hazardous areas. As no

external source of illumination is necessary, both day and

night operation is possible.

† Remote sensing 2. Due to the separation between

camera and object, measurement by thermography

should not cause interference with the object and,

hence, acquired data. In reality, some interference will

be caused by the camera shielding the object from some

radiation, which would otherwise be incident upon it

and by the radiation reflected and emitted from the

camera itself. These effects can normally be assumed to

be negligible.

† Large monitoring capacity. Thermal imaging cameras

are capable of monitoring temperature at many different

points within a scene simultaneously.

† Visibility. Since thermal radiation can penetrate smoke

and mist more readily than visible radiation, visually

obscured objects can be detected readily.

† Range of measurement. By altering the camera lens

aperture and by introducing various filters, the sensi-

tivity of the system and its response to thermal radiation

can be altered to suit. Typical temperature ranges are of

the order of 220 to 1600 8C.

† Fast response rate. Thermal imaging equipment is

capable of detecting and monitoring rapid temperature

fluctuations to an accuracy of ^0.08 8C.

† Portability. Thermal imaging equipment is lightweight

and can be easily transported. It is also possible to use

the equipment whilst mobile.

† Data manipulation. The recorded data can be monitored

and processed on a standard PC running dedicated

imaging software.

3.3. Problems in applying thermography

† From the above, the radiation reaching a thermal imaging

system is not only a function of the temperature of the

object but also of its emissivity. Since emissivity varies

from material to material, the brightness of different

objects within a scene do not necessarily give a clear

indication of their relative temperatures.

† Any material with emissivity less than one will reflect

radiation from surrounding objects as well as radiating its

own radiation. Thus, the temperature obtained for an

object may be influenced by other objects in the

surrounding area.

† Attenuation of radiation in the atmosphere caused by the

absorption of energy by suspended particles and

subsequent re-radiation in random directions can affect

the obtained results. These effects can be assumed

negligible for cases where camera–object separation is

small.

There are additional problems when applying thermo-

graphy outside. The external presence of items such as

bridges, trees, embankments and sewers, will affect the

temperature. Other factors that may affect the temperature

are the time of the day and whether the object is heating or

cooling also affects the results. Also, overhead electric lines

can limit the height from which a survey can be conducted.

However, the thermographic survey can be conducted at

speed, as no contact is needed.

4. Practical applications of infrared thermography

4.1. Case history: investigation of a concrete bridge

4.1.1. Introduction

The focus of this investigation was to detect delamina-

tions where the current practice is to ‘tap’ test the underside

of the bridge deck—coin-tap test. This is a time consuming

and labour intensive technique, which requires contact with

the bridge deck—which can be difficult if the bridge is over

a live highway, requiring lanes of the road to be closed.

Infrared thermography has been proven mainly in the USA

to identify delamination of bridge decks [4,5]. There is an

ASTM D4788 (1997) standard, which describes the

conditions and suitable approach for an infrared survey of

a bridge deck. Infrared thermography will measure the

temperature of the surface of the concrete; and delaminated

areas should show up as areas of different temperature

compared with the bridge deck as a whole. This technique

can be carried out from a distance from the underside of the

bridge deck, e.g. from the hard shoulder in the case of a

motorway.

4.1.2. The project case study

The objective of this project was to undertake an infrared

thermographic survey on one span (span 5) of a bridge on

the M1 motorway in Northamptonshire in the UK. In Fig. 3

the point labelled A shows where the site is located. Fig. 4 is

a picture of the site showing the highway and nine spans.

Fig. 3. Location of site.


The spans investigated were the five right–hand spans. The

arrow points to the main span under investigation with

known areas of delamination.

4.1.3. Experimental technique and equipment

The survey was conducted over a 2-day period

(December 2000), to see if the temperature conditions

were more favourable on either day. The survey was carried

out stationary from ground level. Infrared images were

recorded along the span of the bridge deck from one end

using an Agema Thermovision 900 Camera fitted with a 208

lens and connected to a laptop computer using imaging

software. Visual images were recorded with a digital

camera. The experimental set-up is shown in Fig. 5.

The infrared camera was used to record the temperature

of the surface of the bridge, looking along the length of the

span. Identifying surface temperature anomalies may show

areas of potential delamination.

4.1.4. Results

Due to the time efficiency of the infrared thermographic

technique, spans 1–5 plus the south abutment were scanned.

In some figures hotter areas were noted near edges due to

direct sunlight—this did not indicate a delamination.

4.1.5. Span 5

Figs. 6 and 7 are looking down (west to east) span 5 (with

known delaminations). In Fig. 6 the camera is set to

include all temperatures in the frame. Fig. 7 is set to

exaggerate the temperature differences on the bridge deck.

The following parameters were entered into the set-up

Fig. 4. Photo of the location of the site.

Fig. 5. The infrared camera and laptop.

Fig. 6. Infrared image looking down a span while tap testing was

undertaken.

Fig. 7. Same infrared image as Fig. 4 but a tighter temperature range.

Fig. 8. An image of all three areas of delamination in this span.


software: the distance from the camera to the object to be

12 m, the atmospheric temperature to be 11 8C and the

humidity to be about 70%. It can be seen from Fig. 7 that

there are 2 bands of concrete that are warmer than the

surrounding concrete temperature—this is shown by the

light colour (where the yellow arrow is pointing). The band

directly above the scaffolding is an area of known

delamination. The other area was ‘tap’ tested on the 5th

December 2000 and found to be an area of delamination not

previously found.

Fig. 8 shows the two warmer bands as shown in Fig. 7

and a band/area of delamination closer to the camera. The

areas of delamination are shown more clearly by using an

analysis tool of highlighting a temperature band with a

certain colour, in this case green. This closer area is also a

known area of delamination—Fig. 9 shows a close-up of

Fig. 10. Span 4 showing no areas of delamination.

Fig. 11. Span 3 showing an area of delamination.

Fig. 12. The south abutment showing an area of damp and the pipe.

Fig. 9. Close up of the most westerly area of delamination.


this area. The limitation of this is that there is nothing to

reference this area to. Fig. 9 also has the green band showing

the area of delamination as well as a yellow arrow point to

the area.

4.1.6. Span 4

Span 4 was tested and no areas of delamination were

found, as shown in Fig. 10. This survey was undertaken on

6th December, the image is taken from the east end of the

span looking towards the west. The west end, which can be

seen in Fig. 10, is warmer than the centre of the bridge—this

is due to the heating effect of the sunshine on the west end of

the bridge.

4.1.7. Span 3

Span 3 was investigated and a possible area of

delamination was found—it is highlighted in Fig. 11. Fig.

11 has a different colour scale to highlight the area of

delamination. This area of delamination was on the second

construction joint in from the west.

4.1.8. Spans 2, 1 and abutment

The other spans were tested and no obvious areas of

delamination were found. The south abutment was also

tested and an area of damp was found near the pipe this is

shown in Fig. 12.

Table 4

Results of the infrared survey

Defect Location Previously identified by

‘coin-tap test’

Delamination West end of span 5 Yes

Delamination East end of span 5

(3rd construction joint in)

No

Delamination East end of span 5 Yes

Delamination West end of span 3

(2nd construction joint in)

No


(near far end of span)

Yes

Delamination East end of span 5


Yes



Yes

Damp patch South abutment Yes

Fig. 14. Showing the east side of the Kilbucho bridge.

Fig. 15. Showing the west side of Kilbucho bridge.Fig. 13. Location of Kilbucho bridge.


Some of the smaller areas of the already known

delamination were tested at both ends of the individual

spans. The infrared camera was unable to identify these

areas since they were masked by the thermal end or edge

effects, due to direct sunshine effects.

4.1.9. Summary of findings

Table 4 shows the areas of delamination that the infrared

camera found as a result of this survey.

4.2. Case history 2: investigation of a masonry bridge

The objective of this case study was to undertake an

infrared survey of a masonry arch bridge. Kilbucho bridge is

a single span low rise skew brick arch with stone walls. The

overall width of the bridge is 5.1 m and the arch spans 3.6 m

with a rise ratio of 3. The stone parapets are 1.1 m high and

0.3 m thick. The skew of the bridge is 208. The multi-ring

brick arch barrel is 0.36 m thick, and the fill is 0.3 m thick at

the crown. Fig. 13 shows the location of the bridge, where

the arrow points to the bridge. The bridge was located at

Kilbucho on the C road that connects Broughton and Biggar

skirting to the north side of Goseland Hill. The main use of

Fig. 16. Image showing the infrared camera surveying the bridge.

Fig. 17. An unprocessed infrared image of Kilbucho bridge.

Fig. 18. A visual image showing the same area as Fig. 17.

Fig. 19. The processed image of Fig. 18.


this road is to access the local farms. This bridge, spans the

Kilbucho Burn. The bridge is located 1 mile from Kilbucho,

7 miles from Biggar, 33 miles from Edinburgh, 58 miles

form Glasgow and 77 miles from Carlisle. Figs. 14 and 15

shows pictures of the bridge.

Recently there has been an accident on the bridge where

a vehicle has driven into the north end of the east side of the

bridge knocking three stones of the east parapet into

the water, this can be seen in Fig. 14. The local land around

the bridge is prone to localised flooding and the bridge can

sometime be submerged by water.

An infrared survey of this bridge was undertaken to

identify possible areas of defects, such as the presence of

moisture in the fill of the masonry arch bridge. The infrared

survey of the Kilbucho bridge was undertaken from both

sides of the bridge on Thursday 31st January 2002. The

weather on site was very windy, rainy, cold, and over cast.

These are not the ideal conditions for an infrared

thermographic survey, as the bridge would almost be in

thermal equilibrium.

The infrared survey was undertaken using an Agema

Thermovision 900 Camera fitted with a 20 by 108 lens and

connected to a laptop computer using imaging software. The

experimental set-up can be seen in Fig. 16, showing the

laptop, power supply, tripod and infrared camera.

Due to the restrictions imposed on the survey by the

physical constraints caused by the surrounding environ-

ment, the whole bridge could not be viewed in one image so

the bridge was viewed in sections. Fig. 17 shows an

unprocessed infrared image of one section, whilst Fig. 18

shows the corresponding visual image. In Fig. 17 it is

possible to make out the outline of the left–hand side

(south-side) of the bridge. The initial temperature range is

4.8 to 24.2 8C. Within the infrared image the temperatures

are represented by colours where the higher the temperature

within the range in the image the lighter the colour and the

colder the temperature the darker the colour. It can be seen

that sky behind the bridge is very cold. Even on this

unprocessed image it is possible to pick out a number of

features, such as the plants to the left of the bridge and the

bridge itself.

In the processing of the infrared image a number of

assumptions were made:

† the emissivity e ¼ 0:8;

† the distance from the camera to the bridge ¼ 5 m;

† the atmospheric temperature ¼ 4.5 8C;

† the ambient temperature ¼ 4.5 8C.

A reduced temperature range was chosen so that it would

include all the objects of interest reducing the effects of the

extremes of plants and the sky. The effect of this image

processing is shown in Fig. 19.

Fig. 19 shows the processed image of Fig. 18 and it can

be seen that the parapet of the bridge is darker/colder

towards the centre of the bridge, but this is what is

expected as the parapet has a low thermal mass. The plant

to the left of the bridge can be seen as a light/warm area

and the light lines/areas in the foreground are branches of

the plants blocking the view of the bridge at that area.

Fig. 20 shows an infrared image of Fig. 21. Within the

image, it is possible to identify the brick arch as it is a lighter

colour/warmer than the stone.

Fig. 22 shows another infrared image of the bridge; this

image is of the arch to the right of Fig. 20. Fig. 23 show the

visual image of Fig. 22. It can be seen that the temperature

of the stone wall to the right of the arch and the right–hand

side of the brick arch is a darker colour/colder than the rest

of the image. This may be due to the presence of water

behind the surface. It is possible to see the tree in the

foreground on the right of the image.

Fig. 20. A processed infrared image.

Fig. 21. Visual image of Fig. 20.


The west side of the bridge was surveyed next. The

major problem faced with surveying this side of the

bridge was that there was a large tree. This can be seen

in the infrared image, Fig. 24 as the tree masks any

detail below the parapet, Fig. 25 shows a visual image of

this.

The problems involved with infrared surveying of the

west side of the bridge are that there is a large tree in

the way, the slope of the side of the river is very steep, the

bridge is hidden in the dip and the bridge is very small—so

any areas of moisture, delamination, or voids will

encompass the whole bridge.

Table 5 shows the areas thermal anomalies found on

Kilbucho bridge from the infrared survey.

5. Conclusions

Thermal imagers offer an excellent means of making a

qualitative determination of the temperature of a surface, but

absolute temperature measurement is fraught with difficul-

ties. The radiation received from an object is a function of its

temperature, spectral emissivity, and reflections from its

surroundings along with atmospheric transmission. Con-

sideration needs to be given to the fact that, outdoors, many

factors alter the surface temperature of the object under

investigation. The weather can have a major effect. Sunlight

may increase the temperature and wind may decrease the

temperature of an object. Rain will lower the temperature of

an object through both conductivity and evaporation, it will

also cause a change to the emissivity.

Within the case study more bridge spans were tested than

originally planned due to the efficiency of the infrared

Fig. 23. The visual image of Fig. 22.


Fig. 25. Visual image of Fig. 24.

Table 5

Anomalies on Kilbucho Bridge

Location of anomaly Possible reason Surface condition

South side of bridge on the

left–hand side

Water in the fill Dry

South side of bridge on the

right–hand side

Water in the fill Dry



thermographic technique. From the survey conducted it can

be seen that delamination can be identified using infrared

thermography, even though the survey conditions were

imperfect. Two previously unidentified areas of delamina-

tion were found, one of which was ‘tap’ tested and confirmed

as an area of delamination. All but one of the areas of

delamination which were previously found using the tap

testing technique, were identified by infrared thermography.

The area not detected was close to the edge of the slab and

subject to local sunshine. Some of the areas identified were as

small as 20 cm in diameter. The difference in the temperature

of the delaminated areas compared with the non-delaminated

areas was approximately 0.2–0.3 8C.

Acknowledgements

The authors wish to acknowledge the financial support of

The UK Highways Agency, London under Contract No.

3/185. They also wish to acknowledge the facilities and

funding made available by the University of Edinburgh.

References

[1] Buyukozturk O. Imaging of concrete structures. NDT&E Int 1998;

31(4):233–43.

[2] Washer GA. Developments for the non-destructive evaluation

of highway bridges in the USA. NDT&E Int 1998;31(4):245–9.

[3] Weil GJ. Non-destructive testing of bridge, highway and

airport pavements. No Trenches in Town Proceedings of International

Conference, Paris, France; 12–14 October 1992. p. 243–6.

[4] Weil GJ. Non-destructive of bridge, highway and airport pavement.

International Conference on NDT of Concrete in the Infrastructure,

Deardon, Michigan; 9–11 June 1993. p. 93–105.

[5] Weil GJ. Non-destructive testing of bridge, highway and

airport pavements. International Symposium on Non-Destructive

Testing in Civil Engineering (NDT-CE), DGZfP, Berlin, vol. 1.;

26–28 September 1995. p. 467–74.

[6] Adams AK, Gill AS, Ek JR, Nelson RA. Contribution of conduction

to total infant energy expenditure. J Thermal Biol 1998;23(5):

267–72.

[7] Talwar DN, Jogai B, Loehr JP. Novel type II strained layer

superlattices for long wavelength infrared detectors. Mater Sci

Engng 1998;B51:12–17.

[8] Can M. Simultaneous convective heat and mass transfer in

impingement ink drying. Int Comm Heat Mass Transfer 1998;

25(6):863–74.

[9] Kulkarni VK. Use of infrared thermography in the restoration of a

building. Indian Concrete J 1996;323–5.

[10] Donnelly LJ, McCann DM. The location of abandoned mine workings

using thermal techniques. Engineering geology, vol. 57. Amsterdam:

Elsevier; 2000. p. 39–52.

[11] Engelbert PJ, Hotchkiss RH, Kelly WE. Integrated remote sensing and

geophysical techniques for locating canal seepage in Nebraska. J Appl

Geophys 1997;38:143–54.

[12] Burnay SG, Williams TL, Jones CH. Applications of thermal imaging.

Bristol: Adam Hilger; 1988.

[13] Yang WJ. Handbook of flow visulization. Washington, DC: Hemi-

sphere; 1989. p. 531–53.

[14] Moropoulou A, Koui M, Tsiourva Th, Kourteli Ch, Papasotiriou D.

Macro- and micro- non destructive tests for environmental impact

assessment on architectural surfaces. Mater Res Soc Symp Proc 1997;

462:343–9.

[15] American Standard Test Method, Detecting delamination in

bridge decks using infrared thermography, D4788, vol. 4.03.; 1997.

p. 474–5.

[16] Offermann S, Bissieux C, Beaudoin JL. Statistical treatment applied

to infrared thermoelastic analysis of applied residual mechanical

stresses. Rev Gen Therm 1998;38:718–24.

[17] Agema infrared systems. Irwin Research 1.1. Operating Manual.

[18] Drysdale D. An introduction to fire dynamics. New York: Wiley;

1997. p. 32–3.

[19] Schmidt FW, Henderson RE, Wolgemuth CH. Introduction to thermal

sciences. New York: Wiley; 1993.


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