ungrouted cell inspection tool for masonry walls

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Keywords: INTRODWhen reinecessaryProblemscan signiresponse,portion oessential displacemduring cotwo wallaccumulareinforceconstructthe masodemonstrdevelopin

ROUTED

A. 1PhD Cand

hD, Assistant P

PhD, Martini, M

tudy, a new eloped. The loyed to de

tion defects. ence of the sesign. To exin concrete

mined groutd sensors i

cially availabeld for rapid usually requ

concrete, bloc

DUCTION inforcementy for bond s associated ificantly alte, or lower st

or complete wespecially i

ment relationonstruction(Sls is signifation of ment(Shedidtion of reinfonry construc

rated that sng a proper

D CELL IN

A. Nassr1,

didate, Departm

Professor, Depa

Mascarin and G

technique fconcept, ba

sign coplanaAn analytic

sensor geomxperimentally masonry wted and unin a laboratble portable inspection o

uired by othe

ck,grout; measu

t is introducdevelopmewith incom

er the respotrength, andwalls. The en shear wall

nship of a soShedid et al.ficantly diff

hardened d et al., 2orced masonction industrsuch constrtechnique t

15th Internatio Mason

Florianópoli

NSPECTIO

M.T. Shedi

ment of Civil ECanada.nass

artment of Civishedidmm

George Chair ineldak@

for detectingased on detear capacitancal model an

metrical paray verify the

walls were mngrouted celtory setting.capacitance

of masonry er more expe

urement; non-d

ced in masonent between mplete groutonse of masd may requirengineering ils designed

ound wall an., 2005). As ferent. Figu

mortar dr2005), whicnry block wary (CMDC, ruction erroto detect poo

onal Brick andnry Conference

lis – Brazil – 2

ON TOOL

id2, and W.W

Engineering, Msraa@mcmasteil Engineering,

[email protected] Masonry Des

@mcmaster.ca

g ungrouted ecting the lonce sensors wnd finite elemameters on th

model, dielmeasured. In

lls was con. The propoe meter woulstructures wensive and ti

destructive tes

nry constructhe steel

ting, unfilledsonry walls re demolitioinspection ato resist sei

nd a wall witcan be seen

ure 2 showsropping onh is a comalls. Test res2007), and

ors are notorly grouted

d Block e

2012

L FOR MA

W. El-Dakh

McMaster Univeer.ca , Ain Shams Unca sign, McMaste

cells in conocal dielectriwith high sement simulahe sensor siglectric prope

addition, a nstructed, aosed sensor ld facilitate

without the nime consumi

ts; sensors.

ctions, groutreinforcemed cells, and and may re

on and reconand detectionsmic forces.th accidentan from the fs the ungron the wmmon conssults and furmasonry det uncommod and ungro

ASONRY

hakhni3

ersity, Hamilto

niversity, Cair

er University, C

ncrete block ic permittiviensitivities tations were ugnals and to

erties of varimasonry w

and inspectedesign, co

employing teed for sophing methods

ting of the ent and mas

unbonded result in an unstruction ofn of unfilled. Figure 1 sh

ally unfilled figure, the reouted cells

wall’s horizstruction mirther commusign and con

on in Northuted cells, i

Y WALLS

on,

ro, Egypt.

Canada.

constructionity variationto detect sucused to asseo optimize thious materiaall containined using th

oupled with this techniquhisticated da.

block cells sonry blockreinforcemeunsatisfactorf a significa

d walls cells hows the loalower cours

esponse of thattributed

zontal sheistake durinunication winsulting firmh America.it was kept

ns ns, ch

ess he als ng he

a ue ata

is ks. ent ry

ant is

ad es he to

ear ng ith ms In in

mind thatuse and infor such cpartial orVarious nand to depromisingWilliamsconcrete Sadri (20Ultrasonimedium, collected voids anAlthoughits limiteOther ND(Pieraccinlimited peThe objeaccidentaof materidevelopeand, thuswall betwin develoelement msensor detechnique

Figure

t the techniqnterpret, espconstructionr complete denon-destruct

etect voids ang for their a

s et al. (199block walls

003) to locatic technique

and the nedata. More

d internal ch infrared theed defect detDE techniquni et al. 200enetration deective of thially ungrouteial dielectricd coplanar s, can be app

ween the eleoping the prmodels are esign and ope.

1: Envelop

que should bpecially, in ren problems, temolition oftive evaluatind ungroutedapplication i97) used imps, and in a me voids, and

es have seveed for highe recent resecavities in mermography tecting depth

ues such as m7) were alsoepth. is study is ed zones in c signatures sensors havelied to the m

ectrodes. In troposed capalso used foptimization

e of the load

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-200

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100

200

300

400

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Florianópoli

be quick to aeal-life applthe associatef the walls wion (NDE) td zones in min damage dpact-echo ulmortar-filled

d to evaluateeral shortco

hly experienearch projectmasonry wafacilitates inh, as it is omicrowave

o associated

to present masonry conusing pract

e the benefitmasonry wallthe followin

pacitance tecor the propoprocedures,

d-displacem

60 -40 -20Latera

.7 -1.1 -0.6



apply, inexpeications. Alt

ed cost and dwith such def

techniques hmasonry walldetection in ltrasonic ford collar joine the bondingomings suchnced operatots have demalls using innspection of

only effectiv(Bois et al. with difficu

a new in-sinstructions btical and cot that the senl from one si

ng sections, chnique is hosed capacit and experi

ment for the

0 0 20al displacement (m

6 0.0 0.6% Drift

d Block e

2012

ensive, and mthough repaidetection limfects. have been uls. Ultrasoniconcrete anr detecting vnt. The samg quality in

h as the reqors to prope

monstrated thnfrared thermf large areas,e for detect1998), and lties in their

itu NDE tebased on detst-effective nsor electrodide, instead the theoretichighlighted. ance sensormental verif

two test wa

40 60mm)

1.1 1.7

Damaged w

Reference w

more importir techniques

mitations typi

used to evalic techniquesnd masonry voids in groe technique stone mason

quirements oerly acquire he possibilitymography (M, the main diting near-surground pen

r results inter

chnique fortecting the lcapacitancedes are in thof having tocal backgrouAn analytic

. This is folfication of t

alls(Shedid e

80

2.2

wall

wall

tantly, easy s are availabically result

uate damags proved to bconstructionouted cells

was used bnry structureof a couplinand interpr

y of detectinMeola 2007isadvantage rface damagnetrating radrpretation an

r detection local variatio sensors. Th

he same plano sandwich thund employecal and finillowed by ththe develope

et al., 2005)

to ble in

es be ns. of by es. ng ret ng 7). is

ge. dar nd

of on he ne he ed ite he ed

)

Fig COPLANThe propmaterial different capacitanelectrodegrouted csurface o

The same

air which(Gevorgi

o effC

where o of dielectfirst kind

MaLay

GroLay

gure 2: Unfi

NAR CAPAposed techncompositionparts of the

nce.The propes of width, cells, two layof the face sh

e model is u

h is equal toanet al. 2003

'( )

( )o

o

K k

K k

(the permitttric permittiv

d, k is the mo

Figure 3:

sonry Facyer

uted or Eer

illed cell inf

ACITANCEnique relies ns of concree masonry wposed coplas, with spa

yers of grouthell and diel

used for unfi

o 1.0. The to3) can be com

tivity of freevity of the twodulus of the

: Coplanar

Emp

ce Shell

mpty


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formation in

E SENSOR Ton detectin

ete block wawalls, as a reanar capacitacing, 2g, ot and masonlectric perm

filled cells, w

otal capacitamputed as:

e space) is eqwo substrate e elliptic inte

capacitance

pty

s



n one of the

THEORYng the variaalls. The chasult of defectance senso

over a layerenry face shell

mittivities ofwhere 1 is t

ance per un

qual to 8.854layers.K(k)

egral as descr

e sensor mo

2g

d Block e

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test walls(S

ations of theange in dielcts, producer can be med media asl with height

1 and 2 resp

taken as the

it length for

41x10-12 F/mis the compribed in Nas

del over a la

Reinforcemenin empty cell

s

Shedid et al

e dielectric lectric perms change in

modeled as s shown Figts h1 and h2 pectively, ar

e dielectric p

r the two lay

m, and εeff islete elliptic i

ssr et al. (200

ayered med

nt un-encased w

h2

h1

., 2005)

signatures ittivity withthe measuretwo adjace

gure3-(a). Ffrom theoutre considere

permittivity

yers substra

(1

s the effectivintegral of th08).

dia

with grout

in hin ed

ent or ter ed.

of

ate

1)

ve he

CAPACIDue to thdimensiomodel, wsystem. Uedgesof tpredicted Thavailable results ofdevelopea set of proportio

Figure 4

SENSORFor an acoptimizedcompositsensor decells shogeometriccells was SIGNALThe signasignal strstable and

ITANCE SEhe general uons of the prwhere (l >s),Unlike 3D mthe electrod

d and measurhe 2D modfinite eleme

f the FEM ad coplanar ccurves (fiel

onal to the fie

4: The electr

R DESIGN Accurate detecd. The capactions, materiesign, differ

ould result ical paramete identified a

L STRENGTal strength irength leadsd robust resu

y

E

Masonry fac

Grou

ENSOR FINuniformity ofoposed copl, a 2D finitemodelling, 2

des. Howevered capacitandels consideent modellinanalysis withcapacitance sld lines) aligeld strength.

ric field and

AND OPTIction of ungrcitance acrosial thicknesrences in mn a significers of the c

as the govern

TH is an imports to a high ults. Figure 5

x

Equipotential

ce shell

uted cell


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NITE ELEMf the electriclanar sensor,e element sim2D simulatier, these effnce results aered in this ng (FEM) pah the electricsensor over agned along .

d equipotentof conc

IMIZATIONrouted cells ss the sensorses and theaterial diele

cant change apacitance s

ning factor as

ant aspect toSignal-to-No5 shows the

Elines



MENT MODc field along, and in ordemulation waions neglect fects resulteas will be sho

study wereackageMAXWc field distriba grouted cethe local fi

tial lines obtcrete block

N in masonry

rs depends oe sensor’s gectric proper

of the senssensors on ts will be dis

o be consideoise Ratio (change of th

Electric field lin

d Block e

2012

DELLINGg one directier to be conas selected f

the fringe-ed in minor own later. e constructeWELL 2D (bution and e

ell. The electield directio

tained from

walls, the son the dielecgeometrical rties betweesor output sthe capabilitcussed in the

ered in any (SNR) whiche predicted

nes

ion comparesistent with for modellin-field effects

differences

ed using a (2003).Figurequipotentiatric field is rn with spac

m FEM for a

ensor paramctric values o

parameters. n grouted asignals. Thety of detectie following

sensor desigh, in turn, lcapacitance

ed to the oththe analytic

ng the sensins at the outs between th

commercialre 4 shows thal lines for threpresented bcing inverse

a grouted ce

meters must bof the materi

With propand ungroutee influence ing ungroutesections.

gns; as a higleads to moe using Eq. (

her cal ng ter he

lly he he by ely

ell

be ial

per ed of ed

gh ore 1)

with the capacitan

* /C C where C effective

space in (on the cathan the electrode

SENSORAnother how deethicknessexponentmaterialsdielectricfringing coplanar distance beffective (Nassr et T=1.35g+

electrode nce, C, in ter

eff ol

is the actuadielectric p

(F/m). Fromapacitance ssensor with

e width, s.

R PENETRAimportant fa

ep the elects, as shown tially througs nearest to tc permittivitielectric fielcapacitancebetween thesensor peneal. 2008), an

+0.65s

width, s, arms of a dim

al capacitanpermittivity

m Figure 5, itsignals, wheh wider gap

Figure 5: N

ATION DEactor in senstric field efin Figure 6-gh the matethe electrodies of materid sensors (L sensor wou

e centrelines etration depnd can be gi


Florianópoli

and electrodmensionless p

nce in (F), lfor the subs

t can be seenreas a sensop spacing. T

Normalized

EPTH sor design isffectively pe-(a). It shoulerial thicknes have greaials deep in tLi et al. 20

uld depend oof the two

pth depends iven by:

(3)



de spacing, parameter, C

is the lengtstrate layers

n that the eleorwith narroThe capacit

capacitance

s the sensor enetrates intld be noted

ness. Therefater influencthe test spec

004), the penon the sensorcoplanar eleon the sele

d Block e

2012

g. It is coC* as:

th of the ele, and o i

ectrode spacow gap spactance signal

e versus s an

penetration to a test spthat the elec

fore, the dice on the secimen. It wanetration der geometry aectrodes. It wction sensor

onvenient to

ectrode in (s the permit

ing has a strcing yields hl also increa

nd g

depth, T, wpecimen or ctric field strielectric perensor signalss expected t

epth, T, of tand be propowas demonstr geometrica

o express th

(2)

(m), εeff is thttivity of fre

rong influenchigher signaases with th

hich indicatthe materi

rength decayrmittivities s compared hat, similar the developeortional to thtrated that thal parameter

he

he ee

ce als he

es ial ys of to to ed he he rs,

Figure 6penetratinnarrow an The optimthe sensohighest sidepths fo

Figu

EXPERIMEASUThe accuconcrete experimeto determknown th625 mm2

between grips of adeterminecapacitan

from the tested to the measu

6-(b) shows ng deeper innd closely sp

mal design oor geometricignal strengt

or a certain b

ure 6: (a) ThPen

IMENTAL REMENT Ourate measumasonry co

ental data to mine the dielhickness, d, b2), were usedthe materiala non-condued experim

nce produced

total measuobtain diffeured capacit

that sensorn the materpacedelectro

of the coplancal parameteth. This, in tu

block geomet

(a)

he penetratinetration de

VERIFICAOF DIELECurement of mposition isthe predicateectric permibetween twod as a parall and coppeructive clamp

mentally by d by the me

ured capacitaerent data poance, C, as f


Florianópoli

rs with widrials further odes.

nar capacitaners in order urn, dependstry.

on of the eleepth as a fu

ATION CTRIC PROthe dielectrs of prime imed analyticaittivity of a mo parallel colel plate cap

r plates, the as shown ina single c

easuring lea

ance. Therefooints to estabfollows:



de electrodesaway from

nce sensors ito get a sufs on the spec

ectric field t

unction of th

OPERTIESric propertiemportance inl and FEM smaterial is to

onductors. Twpacitor electrmaterial spen Figure 7-(

capacitance ads, leadC , wi

fore, four samblish a relati

0

10

20

30

40

50

60

70

25

T (

mm

)

d Block e

2012

s and widelm their surfa

is achieved bfficient penecific applica

through thehe sensor ge

S OF MATEes of differen order to fasimulation reo sandwich awo 25 mm srodes. In or

ecimens wera). Dielectrimeasuremen

ill lead to b

mples with dionship betw

1520

5

S (mm)

ly spaced araces than the

by the propeetration depthation and des

(b)

e material laeometry

ERIALS ent materialacilitate corresults. A sima disk of thesquare copperder to ensurre placed betic permittivitnt. This is e isolated a

different thicween the thic

510

re capable e sensor wi

er selection h, T, with thsired detectio

ayers, (b)

ls of grouterelation of th

mple technique material ofer plates, (Are full contatween the twties cannot b

because thand subtracte

cknesses weckness, d, an

510

1520

2

g (mm)

of ith

of he on

ed he ue f a

= act wo be he ed

ere nd

2530

leadC C

Figure 7-thicknessfollowingmaterial’were foun

Figure 7determ

TEST SPA half-scfully groexpect foStyrofoamis equal tA coplanand an ecopper tagap betwestimatedUsing thesurface o0.10% aconnectio

Material s

o r

1A

d

-(b) shows ts, 1/d, for theg section. Fos dielectric nd to be 5.21

7: Evaluatinmination set

PECIMENcale square mouted columnor one cell m during theo that of air)

nar capacitanlectrode len

ape and mouween the coppd to be 25 mme coplanar seof the wall. ccuracy. Thon to the sen

Coaxial c

specimen

the capacitae concrete blor each matepermittivity1 and 5.14, r

(a)

ng the dielectup, and (b)

masonry walns, C-1, anin column Ce grouting pr). The rest of

nce sensor wngth, l = 50 unted togethper electrodem. ensor, the 29Measureme

he LCR mensor by coaxi

Cla

cable


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ance plotted lock and grorial, a linear. The dielecrespectively.

ctric properthe capacit

thi

llet, 4 block d C-7 (see C-5, and twrocess to simf the cells w

with an electrmm was faer on a thin es. The pene

9 grouted anents were coeter was prial wires.

Cap

acit

acne

(pF

)

amp



as a functioout materialsr relationshipctric permitti.

rties of matetance as a fuickness

wide by 8 bFigure 8).

wo cells in cmulate air (th

were kept ungrode width sabricated. Th

plastic sheeetration dept

nd the 35 unollected usinrovided with

In30

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6Gro

Ma

d Block e

2012

on of the res used in thep was plottedivity of the

erials, (a) thunction of th

block high, wAnother twcolumn C-3he Styrofoamgrouted, as sh

= 25 mm, ahe sensor elet to maintaith, T, of the

ngrouted cellng an INSTEh a test fix

verse dielectri40 50

out, grout = 5.14

asorny, block = 5.2

eciprocal of e wall test did with a slopconcrete blo

(b)

he dielectriche inverse o

was construwo columns

, which wem’s dielectrihown in Fig

a gap spacinglectrodes wein the constasensor, from

ls were scanEK 816 LCxture that f

ic thickness , 160

21

(4)

the dielectrscussed in th

pe equal to thock and gro

permittivitof dielectric

ucted with twwere groute

ere filled wiic permittivi

gure 8. g, 2g = 8 mmere made of ant separatio

m Eq. (3), w

nned along thCR meter wifacilitated th

1/d, (1/m)70

d

V

ric he he

out

ty

wo ed ith ity

m, f a on as

he ith he

80

d

R-1

R-2

R-3

R-4

R-5

R-6

R-7

R-8

TEST REFigure 9-measuredcapacitanlow value

5.14. The1.52 pF ungroutedfrom the Figure 9-grouted cobtained the expertheoreticabetween FEM doelength. Insensor/wa

Table

GrouteUngrou

Sensor sesensitivitywith grou

C-1 C-2 C-3

ESULTS -(a) gives thed capacitancnce decreasee of the diel

e mean valuerespectively

d cells of 2.5measured ca

-(b). The vocells appear to verify thrimental datal results ovexperimenta

es not accounn addition, dall contact q

e 1. Compar

ed cells uted cells

ensitivity is y is an indicuted cells. Th

C-4 C-5 C-6

Figu

e capacitancces were afd in these relectric permi

es for the mey with aver56 %. The capacitance oids and ungas light reg

e experimenta, analyticaver-predictedal data and thnt for the fri

disturbance fquality had o

rison betwee

Experimenta

an importancation of hohe sensor sen


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C-7 C-8

ure 8: Maso

ce measuremffected by thegions. The ittivity of ai

easurementsrage coefficapacitance p

obtained fromrouted zone

gions. The antal results. Aal model, and the experimhe theoreticainging end efactors such ther contribu

en the exper

al Measurem2.63 1.50

nt factor usew much sennsitivity is d



Grouted Cell

Ungrouted Cel

nry wallet s

ments for diffhe presencedecrease of r, air =1, c

s of grouted cient of variprofiles fromm the three ss can be ide

analytical anA comparisond FEM simmental valual results maeffect as elecas the stray ute to these d

rimental an

ments (pF) A

ed to investinsor signals defined as:

d Block e

2012

l

specimen

ferent cells oe of voids af the output sompared to

and ungroutiation (COV

m the measursensor configentified by thd FEM simuon between mulations isues by 9% oay be attribuctrodes werecapacitance deviations.

nd theoretica

Analytical M2.841.72

igate the senchange for u

of the inspecand unfilledsignals is attthat of the g

ted cells werV) for bothrements weregurations andhe dark regiulations resuthe results o

s shown in on average. Tuted to the fae assumed to

of the test l

al capacitan

Model (pF) F4 2

nsor performungrouted ce

ungro

cted wall. Thd cells as thtributed to thgrout, groutre 2.61 pF anh grouted ane extrapolated presented ions while thults were alsobtained froTable 1. ThThe deviatio

act that the 2o be of infinilead wires an

nce results

FEM (pF) 2.70 1.63

mance. Sensells compare

outed cells

he he he =

nd nd ed in he so

om he on 2D ite nd

or ed

Figure

% Senso

where grC

ungroutedfound to b The Signfollows(M

CSNR

where gwas foun CONCLThe desigwalls wadielectricto presenperformeresponseswall contidentifyinresults an

Cap

acit

ance

(pF

)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

9: (a)Capac

or Sensitivity

routed and C

d cells. Thebe approxim

nal-to-NoiseMeola 2007)

grouted ungr

g

C C

is the stan

nd to be appr

USIONS gn of a copls presented.

c signatures once or absenced to examins. The devetaining groutng the ungrnd theoretica

C-1 C-2 C-

R-3

(a)

citance mea

y = grouted

gr

C

C

ungroutedC are

e sensitivity mately 40%.

e Ratio (SN):

routed

ndard deviat

roximately 2

lanar capacit The develoon different ce of the grone the influeloped modeted and ungrouted cells. al prediction

-3 C-4 C-5

R-4


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asurements profile for

ungrouted

routed

C

e the averag

of the cop

NR) is anoth

tion of senso

2.

tance sensoropment of th

points alongut. Both anance of differ

els were verirouted cells.There was

n data with e

C-6 C-7 C

R-4



for differenr inspected w

100

ge capacitan

lanar sensor

her importa

or measurem

r for detectinhe sensor wag the wall sualytical moderent sensor gified using . The coplan excellent a

errors attribu

C-8

d Block e

2012

nt cells of thwall

nce measur

r in the stud

ant factor a

ments for the

ng ungroutedas based on urface and coel and finite geometrical measuremen

nar capacitanagreement buted to fring

(b)

e wall, (b) C

rements for

dy conducte

and can be

e grouted ce

d zones in cdetecting thorrelating thelement simparameters

nts performence sensor wbetween the ging end effe

Capacitance

(5

grouted an

ed herein w

estimated

(6)

ells. The SN

concrete bloche variation hese variationmulations we

on the sensed on a blocwas capable

experimentects, and stra

e

)

nd

as

as

NR

ck of ns

ere or ck of tal ay

capacitandifferent ACKNOFinancialof Structu(ORDCFCanada. PCanada MCanadian REFEREBois,J., Cdetection CMDC (2Technica Gevorgiawaveguidsuperstrat Li, X. B.,electric fSymposiu Maxwell Meola,C.vol. 49, p Nassr, Adetecting075702. Pieraccinmasonry Sadri,A. structures Shedid, Mand impaCalgary, Williams"NondestJournal, v

nce. The rematerials ca

OWLEDGEMl support hasures (CEDS)

F) as well asProvision ofMasonry D

n Concrete M

ENCES Campbell,H

n of grout in

2007) Canadal Advisor, C

an, S., Berg,des on multes," Microw

, Larson, S. field sensorum on Electr

2D, V.10, P

. "Infrared tpp. 228-233,

A. A., Ahmeg water intru

ni, M., Pisanwalls," NDT

"Applicatios," NDT & E

M., Hamid, Aact of incomBanff, Albe

s, T. J., Satructive evavol. 15, pp. 4

sults of thean be used to

MENTS s been provi) funded thros the Naturaf mason timeesign Centr

Masonry Prod

H.,Benally, Amasonry," T

da Masonry CMDC, Miss

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