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MATEC Web of Conferences 149, 01015 (2018) https://doi.org/10.1051/matecconf/201814901015
CMSS-2017
Non-Destructive Testing for Building Diagnostics and Monitoring:
Experience Achieved with Case Studies
Ayşe Tavukçuoğlu
Middle East Technical University, Faculty of Architecture, Department of Architecture, Ankara, Turkey
Astract Building inspection on site, in other ords in-situ eaminations of uildings is a troulesome
ork that necessitates the use of nondestructive investigation DT techniues ne of the main
concerns of nondestructive testing studies is to improve in-situ use of DT techniues for diagnostic
and monitoring studies The uantitative infrared thermography
T and ultrasonic pulse velocity
U measurements have distinct importance in that regard The oint use of
T and ultrasonic
testing allos in-situ evaluation and monitoring of historical structures and contemporary ones in
relation to moisture, thermal, materials and structural failures hile the uildings themselves remain
intact For instances, those methods are useful for detection of visile and invisile cracks, thermal
ridges and damp ones in uilding materials, components and functional systems as ell as for
soundness assessment of materials and thermal performance assessment of uilding components n
addition, those methods are promising for moisture content analyses in materials and monitoring the
success of conservation treatments or interventions in structures The insitu DT studies for diagnostic
purposes should start ith the mapping of decay forms and scanning of uilding surfaces ith infrared
images uantitative analyses are shaped for data acuisition on site and at laoratory from
representative sound and prolem areas in structures or laoratory samples aoratory analyses are
needed to support insitu eaminations and to estalish the reference data for etter interpretation of in
situ data Advances in laoratory tests using
T and ultrasonic testing are guiding for insitu materials
investigations ased on measurale parameters The knoledge and eperience on
T and ultrasonic
testing are promising for the innovative studies on today’s materials technologies, uilding science and
conservationmaintenance practices uch studies demand a multidisciplinary approach that leads to
ring together knoledge on materials science and uilding science
ntroduction nfrared therograph and ultrasonic
Building inspection on site, in other ords in-situ testing in the context of uilding
eaminations of uildings is a troulesome ork that diagnostics and onitoring
necessitates the use of nondestructive investigation nsitu DT studies for diagnostic purposes start ith
DT techniues The uantitative infrared field oservations composed of mapping of decay forms
thermography
T and ultrasonic pulse velocity ith visual analyses and
scanning uantitative
U measurements have distinct importance in that analyses are shaped for data acuisition on site and at
regard ne of the main concerns of those non laoratory taken from representative sound and prolem
destructive testing methods is to improve their areas in structures or laoratory samples aoratory
uantitative use on site for diagnostic and monitoring analyses are needed to support insitu eaminations and
purposes The knoledge achieved on
T and to estalish the standardreference data for etter
ultrasonic testing is presented here, mostly ith a focus interpretation of the insitu data
on case studies conducted on historical materials and n order to enhance the accuracy of nondestructive
structures Those case studies are, in fact, research studies investigations, particularly the insitu ones, there is
shaped to develop insitu use of
T and ultrasonic necessity of using more than one DT testing method
testing methods for specific topics related to uilding and supporting the insitu investigation ith laoratory
inspection and monitoring as ell as to discover their tests Advances in laoratory tests using
T and
potentials and limitations in this regard ultrasonic testing are promising to give the hints of using
those methods on site for uantitative analyses, in other
© The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution
License 4.0 (http://creativecommons.org/licenses/by/4.0/).
MATEC Web of Conferences 149, 01015 (2018) https://doi.org/10.1051/matecconf/201814901015
CMSS-2017
CMSS-2017
words, allow making in-situ examinations based on waves passing along a solid material through a certain
measurable parameters. distance between the transmitter and receiver. he
Infrared (IR) thermography is commonly used for measurable parameter of ultrasonic testing is the velocity
detection of building defects, such as thermal bridges, air of ultrasound waves propagating through the building
leakages or moist spots, particularly in the context of material. he ultrasonic pulse velocity () of a
energy conservation. It measures thermal radiation material is related with its physical and mechanical
emitted by the material and depicts the examined area as properties as well as the state of deterioration,
an image in colours corresponding to a predefined moisture water content and presence of discontinuity.
temperature scale. he application of a hot or cold source
ny discontinuity within a material or increase in
to a specific area results in the warming up or cooling porosity is expected to increase the travel time and,
down of the surface area under examination at varying conseuently, decrease the pulse velocity. he
rates. inal surface temperatures differ depending on the measurements can be made by positioning two
thermal properties, specifically thermal resistance and transducers (one transmitter and one receiver) on
thermal inertia characteristics, of the surface and sub- opposite faces (direct transmission mode) or on the same
surface layers. or instance, entrapped moisture in a surface (indirect transmission mode) of the material
porous material increases its thermal conductivity, sample.
therefore decreases its thermal resistance and creates a he measurements taken in direct transmission
kind of thermal bridge. uch a defect is visible in infrared mode ( ) are used for assessing the state of
IR
images as cooler areas. In addition, exposure of wet deterioration of a material and non-visible
surfaces to mild wind or sun increases the evaporation failure discontinuity at deeper layers, such as invisible
rate, therefore accelerates evaporative cooling. It means cracks. he measurements in indirect transmission
that heating the surfaces or wind effect may also enhance mode ( ) provides precise data on estimating
IIR
the visibility of moist areas in infrared images. the depth of a visible crack while investigating surfaces
he IR scanning is useful and time-saving for the in- in layers only accessible from one side. ifficulty in
situ check-up of the overall structure, especially with a access to mutually-perpendicular faces of a building
focus on visible and invisible materials defects, moisture component limits the applicability of direct
and thermal failures, and various materials use. owever, measurements on site. In such a case, there is necessity to
during the in-situ examinations the uantitative analyses establish the reference data obtained from control
of the representative areas are obligatory for the correct samples and correlate the data taken in direct and
interpretation of the problem areas detected in single IR indirect transmission modes. hat correlation makes it
images. hermal monitoring of the problem area by possible to interpret the in-situ data correctly in
means of seuential thermal imaging is a favourable reference to the control data.
techniue for uantitative analysis of the problem area. he combined use of infrared thermography and
his techniue allows taking infrared images in ultrasonic testing enhances the accuracy of the non-
seuences from the target area during the periods when destructive in-situ examination, especially the studies on
the target area is exposed to heating and then cooling soundness assessment.
good correlation is determined
conditions as well as producing differential thermal between the state of deterioration of stone and its thermal
images which show surface temperature differences inertia characteristics. he deteriorated stone samples
between the initial and the last IR images for heating or present lower values and faster warming up and
cooling period. ue to the changes in physical and cooling down rates than the sound ones.
thermal properties of the defect area, the impact of any ome research fields where IR and ultrasonic
failure can easily be followed in differential images. In testing can be useful are summaried as follows–
addition, the temperature evolution in time under heating – detection of visible and invisible defects failures in
and or cooling exposure conditions can be examined by materials and structures, such as deep and surface
the graphs showing changes in surface temperature as a cracks, detachments ,
function of suare root of time. he slope of the linear – detection of different materials use hidden behind the
regression presents the rate of warming up (R ) or the surfaces or buried within the section of building
rate of cooling down (R ) for each target area. hose components
rates are the measurable parameters related with the – assessment of the state-of-deterioration of building
thermal inertia characteristics of materials. hermal materials and their distribution in the structure ,
inertia characteristics of the problem area can also be
interpreted relatively by comparing the warming – failures in functional systems of historic structures,
up cooling rates of problem area in reference to the rates such as water supply and drainage systems -
of sound material (reference area). – assessment of thermal performance of structures as
In short, that investigation techniue is sensitive to well as thermal and moisture failures in structures ,
thermal characteristics of materials. ince thermal ,
characteristics are very related with the physical, – in-situ monitoring of the existing conditions before
physicomechanical and or mechanical properties of and after treatments, success of conservation
materials, changes in those properties can be monitored treatments in historic structures , , .
precisely by uantitative IR thermography. he advances in laboratory tests using IR are also
ltrasonic testing of building materials is based on promising to determine the thermal properties of
measuring the travel time (transit time) of ultrasonic materials and building walls while give the hints for in-
2
MATEC Web of Conferences 149, 01015 (2018) https://doi.org/10.1051/matecconf/201814901015
CMSS-2017
CMSS-2017
situ QIRT investigations to assess moisture content in 4000
y
t
i )
materials [3, 11, 14, 15]. oc s 3000
el /
V m
(
c 2000
oniues
as al1000
r V
t
l
3 Some case studies: prominent U 0
findings and advancements 56% 75% 90%
RH (%)
Here, some case studies are summarized under respective Parallel-To-Fiber Perpendicular-To-Fiber Direction
sueadings it a ocus on te prominent results o Fig. 1. anges in ultrasonic velocit values o timer samples
tose studies and guiding remars related it non due to te canges in moisture content [1].
destructive uilding inspection. Te
measurements eiit te anisotropic
eaviour o timer in relation to ier direction [11].
3.1 Soundness assessment of structural timber Te
IRT values parallel to ier direction are
elements on quantitative basis consideral iger tan up to 3 to 3.5 times iger te
ones perpendicular to ier direction. Te
IIRT
compreensive stud is needed or te insitu values are muc loer tan te
values it a
IRT
soundness assessment o structural timer elements tat ratio o .3 in average or te measurements taen in
involves parallel to ier direction. ased on tese relationsips,
– preliminary laboratory tests on control samples te
values measured on site rom timer
IIRT
deteriorated and nondeteriorated timer samples to suraces in parallel to ier direction can e used to
produce te reerence data on
and termal predict te
IRT values, tereore, te soundness o
caracteristics, timer.
– field measurements taen rom representative prolem In literature, te
values or sound timer
IRT
areas, and are given in te range o 1 to ms [1, ]. Te
– evaluation of in-situ data in reference to the control ultrasonic data or te sound timer control samples
data. measured in perpendiculartoier direction correspond
uc a stud as conducted on to tpes o structures it te data in literature it te
IRT value o
[11] 14 ms in average at 5 RH igure 1 [1,1]. Te
– Te 1t centur traditional timer dellings in same control samples ave te
value o
nara elonging to ttoman
eriod, namel aş IIRT
143 ms in average, measured in parallel to ier
House in te ton o aş and Istilal House in direction [1].
Istilal district Te timer post and eams orming en te timer deteriorates, its densit decreases
te timer rame all o traditional dellings ere and its arming upcooling rates increases. Te sound
eamined insitu
measurements taen in pine samples control samples ave te loest arming
direct and indirect transmission modes and upcooling rates and te igest densit, indicating teir
seuential IR imaging during cooling conditions. iger termal inertia. epending on severeness o
– slanane amii, 13t centur mosue, elonging to deterioration, te visualldeteriorated pine samples
elus
eriod Te timer pillars supporting te roo arm up or cool don aster tan te sound one control
and timer ceiling o te structure ere eamined sample in te range o 1. and 1.. easuring te
insitu
measurements taen in direct canges in arming up or cooling don rates o timer
transmission mode and IR scanning. samples allos assessing teir state o deterioration in
Reerence data estalised te laorator analses comparison to sound reerence samples.
on control timer samples ere used or te precise
interpretation o insitu data.
3.1.2 Evaluation of in-situ data with respect to
reference data
3.1.1 The reference data achieved at laboratory
ome timer eams and posts in timer ramed ouses
Te old and ne pine samples, visualldeteriorated and ad
IIRT values in te range o 133 to 11 ms
sound ones, collected rom te structures ere eamined taen in parallel to ier direction [1]. valuation o in
in terms o densit, euilirium moisture content at situ
data it respect to te reerence data as
various RH conditions,
taen in direct and indirect son tat tose timer elements are still sound. Tat
transmission modes and arming up and cooling rates. result as also conirmed it insitu
IRT
Te
values o timer samples decrease at ig measurements taen in perpendicular to ier direction
moisture conditions [1]. Tis means tat erever cross arrangements or te transducers could e
psicomecanical properties o timer elements eaen made. Tose
measurements in te range o
IRT
en te get et igure 1. Te relationsip eteen 141 ms are in agreement it values given or te
te
values and relative umidit conditions so sound timer material in literature [1, ].
artial
tat microclimatic data is an important input or correct deteriorations on some parts o timer posts and eams
interpretation o te
data, particularl or te insitu could e detected it
values elo te
IIRT
ultrasonic investigations. acceptale range. In sort, insitu
and
IIRT
IRT measurements ave assured te soundness o
3
MATEC Web of Conferences 149, 01015 (2018) https://doi.org/10.1051/matecconf/201814901015
CMSS-2017
CMSS-2017
structural timber elements in some parts and extensive – The deeper cracs at masonry wall, on the other hand,
deterioration in other parts of the structures under presented noticeably slower warming up and cooling
examination. down rates than the sound stone surfaces.
The sound timber elements present even surface – The deepest cracs allowing air leaage through the
temperature distribution in differential IR images while wall section had the coldest initial surface temperature
the deteriorated ones show heterogeneous temperature and slightly cooled down during the heating period
distribution (figure 2). In addition, the cooling rates of due to the accelerated evaporative cooling in the crac
deteriorated and severely deteriorated timber postbeam cavity.
were found to be . and 2. times faster than the
cooling rate of the sound postbeam, respectively . 1000 Depth of discontinuity at jointing = 86mm
This meant that thermal inertia of deteriorated timber s 800
µ y = 8.9674x - 928.75
,
e 600
decreases due to decrease in density and increase in m y = 1.2338x y = 3.4017x - 106.47
t ti
si 400
n
porosity. a y = 0.975x y = 3.6011x - 155.78
r
T 200
0.0dC 0
0
0 30 60 90 120 150 180 210 240 270 300
-1
-2 Distance, mm
-3 Discontinuity through the jointing at the depth of 86mm
Proper adhesion through the jointing
-4
-5 Fig. 3. The slope of regression lines for the tuff stone followed
-6 by proper ointing without any discontinuity (lines in green) and
-7
-7.0dC the change in the regression slope corresponding to the depth of
Fig. 2. artial view from the timber frame wall of İstilal ouse discontinuity at ointing (lines in orange) .
(at the left) the differential IR image showing the temperature
difference between the initial and the last IR images during the 1.5 1.321.44
1.13
cooling period of
seconds . 1.2 1.06
0.9
0.6 0.41
The values taen in perpendicular to fiber 0.40 0.29 0.31
IRT 0.3 0.10
direction from the timber pillars in slanhane amii were 0.0 -0.22
measured in the range of
to ms , . Those -0.3 Superficial Plaster Fracture at Crack on red Deepest
crack detachment jointing - tuff - crack with air
data falling into the reference values obtained neighbouring d=88mm d=147mm flow
IRT plaster
for sound timber show that the timber pillars of the detachment
ratio of warming up rates - defect to sound
mosue are still sound. ratio of cooling down rates - defect to sound
Fig. 4. The ratios of the R (or R ) of cracdefect to the R (or
R ) of soundreference stone surface .
3.2 Crack depth assessment in stone masonry
n insitu examination on structural cracs with a focus 3.3 Identification of emergency areas that
on depth assessment was conducted on a th century needed conservation treatments and their
ttoman mosue in nara, enabi hmet aşa amii monitoring
. This stone masonry structure with a bric upper
structure suffers from serious cracs observed at its walls comprehensive research involved IRT and ultrasonic
and dome due to the differential settlement of the clayey testing supported by the maps of visual decay forms and
ground following the extremely dry seasons of recent laboratory tests was conducted on emrut ağ
years 2, 22. onument, which is an archaeological site located in
y the study, a nondestructive investigation method eastern Turey in the province of ahta dıyaman and
was developed for the estimation of crac depth in a positioned at the top of emrut ağ at 2
m altitude.
structure by the combined use of IRT and ultrasonic The site is in the list of orld ultural eritage since
testing . The depths of cracs in accessible areas were . The study was focused on the insitu examination
predicted by uantitative analyses of IIRT data of the limestone and sandstone statues in emrut ağ
taen parallel to the stone surfaces (figure ). The thermal onument to assess their state of deterioration and to
inertia characteristics of those cracs with nown depths determine the target areas that needed urgent
were defined by uantitative analyses of surface conservation treatments 2, .
temperature data. The cracs which are not accessible for The reference data on and thermal inertia
ultrasonic testing were then able to be monitored by characteristics of sound and deteriorated limestone and
thermographic analyses to identify whether they are deep sandstone samples were produced (figure ). The
or superficial cracs. relationship between the state of deterioration of stone
The superficial and deep cracs have different thermal surfaces and their thermal inertia characteristics was then
responses to exposed conditions which made them easily used for the assessment of problem areas on statues
distinguishable by IRT analyses (figure ). or surfaces. The deteriorated stone samples present lower
instances values and faster warming up (R) and cooling
– The superficial cracs associating withneighbouring down (R) rates than the sound ones. In other words, the
plaster detachments had thermal response similar to weaening in physicomechanical properties causes the
detached surfaces, having faster warming up and thermal inertia of the deteriorated stone samples to
cooling down rates than the sound stone surfaces. decrease.
4
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