Publisher’s version / Version de l'éditeur:
Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.
Questions? Contact the NRC Publications Archive team at
PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information.
https://publications-cnrc.canada.ca/fra/droits
L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.
Technical Paper (National Research Council of Canada. Division of Building Research), 1957-05
READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE. https://nrc-publications.canada.ca/eng/copyright
NRC Publications Archive Record / Notice des Archives des publications du CNRC :
https://nrc-publications.canada.ca/eng/view/object/?id=6e4d8543-5954-4b4c-b319-5001936d64d0 https://publications-cnrc.canada.ca/fra/voir/objet/?id=6e4d8543-5954-4b4c-b319-5001936d64d0
NRC Publications Archive
Archives des publications du CNRC
This publication could be one of several versions: author’s original, accepted manuscript or the publisher’s version. / La version de cette publication peut être l’une des suivantes : la version prépublication de l’auteur, la version acceptée du manuscrit ou la version de l’éditeur.
For the publisher’s version, please access the DOI link below./ Pour consulter la version de l’éditeur, utilisez le lien DOI ci-dessous.
https://doi.org/10.4224/40001176
Access and use of this website and the material on it are subject to the Terms and Conditions set forth at A review of literature on rain penetration of unit masonry
NATroIvAt nEsxAnclr oou$crl OF OA$Ana
DTVTSTON
OF SIrrI*DrNC
RXSEARCII
REVITW OF trTIERATURE ON
PESEIAATION OF IIffiI' UASOTIRY by
Rltchte and W. G. pLewes
llechnLcal paper lyo. 47 of the
Dlvlsion of Buildlng Researcb
OTTAWA I[av L95T T .
PREFACE
fhe Divislon was mad.e ayrare, soon after 1t was formed Ln 1947, of the exlstence of problenrs ln Canada
lnvolvtng rain penetratlon of masonry walls. Srrbsequently through requests for asslstance wlth sush problems and. through field stuclies lt was establlshed that thls subject rvas one of some lmportance and warranted. serlous study by the Dlvislon. Such problens are not peculiar to Canada but are experlenced ln other countrles, rnany of which are now exchangtng information through membershlp 1n the Worklng Group on Raln Penetration of the Internatlonal Counctl for Bulldlng Research Studles and Documentation (CIB) "
Stris paper presents a review of llterature which was begun as the first najor step ln the }lvisionls prograrn of study on raj-n penetral,lon, TLre 52 references on whlch lt ls based are beU-eveil to lnclude the more signlflcant papers ln Eagllsh d.eallng wlth raln penetraiion of unlt masonry. fhese were selected from several hundred papers lanovrn to the wrlters. There are believed to be nore than ten thousand papers deallng wlth vari.ous aspects of masonry and masonry materlals.
Ihe materlal presented. deals for the nost part wlth masonry made fron mortars ln whlch llme, portland cement or mlxlnrres of the two are used. as the cementlng agent.
Masonry cements have not been lncluded., d.espite ttib fact that they are now wldely used. Almost all of the nasonry cements used are sold as proprletary naterlals and they nay vary wldely ln cornposltlon from one product to another. It ls therefore dlfflcult to relate the results of the : relatlvely linited lnvestlgattons, whlch have thus far
been cancled out uslng them, for grrposes of a stufir such a s thls.
ltrls review somewhat naturally reflects the con-cluslons reached by the wrlters as a result of thelr studles. It is now presented. ln the hope that lt w111 be a useful cond.ensatlon of the work of others as weJI as a stlmulatlng and useful gulde to some of the literature on thls subjeot. Several of the test methods for the d,etennlnatlon of materlal propertles commonly referred. to 1n the ltterature have
been appended., along wlth a selected blbllograptry on the subject of unit Easonry.
Ottawa,
Aprtl, 1957 Asslstant N. B. HutcheonDlrector i : : : i i : i . :
----lFFFrr'r! -I II III IY
v
rI
: I XAppenillx A - trfiortar Flow Test (ASIff Speciflcatlon C91-49) Appentllx B - Inttlal Rate of Absorptlon (Srctro?) - (4!m
Speolflcatlon C67-rOl [A3IE O} CONTNNlS
INIRODUCIION
EOIIRY OF RAIN WAIER II{TO UIA],I,S 1. Passage of Ral.n lVater 2. Passage of Rain l[ater
BRTCK 1 . 2 . 1 . 4 .
5
-6 .
7 ,
g ,c
D Er#;;fi'P;fi;
Masonry
M a t g r l a l s . r . . o Itrrough Craoks analO p e n L n g s . . . r . . M A S O I I R Y - C I , A Y . A I S D S I I A L E B R I C K S . . . i . . " t . . .
Sactors Affectlng the Bonct Between Bricks
a n d M o r t a r s ' . . . . ' . ' . Laboratory llests of Ratn Perretratlon . . .. . , r. .. D l s c u s s i o n o f P e r m e a b l l l t y T e s t s . r . . r i o o o o e o o c Effect of Other Brlck Propertles on RaLn
R e s l s t a n o g o . ' . . . r . . . t WOflmanShlp r r, . . . . . . | . . r o I o i . . . . . . . r . . W a l l n e s l g n D g t a l } g . . . . . . ) . o
D u r a b l S - i t y ) ) . . . f . . . . . r t . . . . . . . Connorts Investlgatlbns of Ireakage j.n Aotual
B u i l d . i n g s . . . . . . . 2 2 2
5
5
t7
2L
23
2 5
50
1 5
47
C O N C R E I t s B I O C K M A S O M T . o . . . a . . . . o . ' . . . o ' . ' . . . r ' o ' + 9 ERICT( IIASOI{RY - CONCRETE AND SA$D-IIME BRICKS ... 49 S I R U O $ I R A I . C I T A Y I I I r E I { A r S 0 I I R Y . . . r . . ' . . o ? t . t . . . ' . ' 4 9 T T I N A g U n A t S f O I I E I I A S O N R Y . . . . ' . . . . ' . . . ' . . . r . . . 5 L YIII SIIRFAOE TREAMIEfIS FOR NAItr RESISTANCE . .. .. . .. ..I ' O " ' 51 R E F E R r u C E S . . . t . e t t t t " t t t " " " ' ' ' ' t ' " ' t " ' t ' t I t ' ' " t 5 +IVater Retentlon fest (ASIS{ Spoclfloatlon C91-49) Satrrratlon Coofflolent (4s1ru Speclflcatlon C62-5Ol Selectecl BlbUogra$l1y ou Unl.t lfiasonry
A RE1IIEW OF ITTERATURE ON RAIN PEITETRATTO}I OF UNIT }{ASO}IRY by
T. R.ltchte and !V. G. Plewes
Slnce 'lts formation ln 1947 mar\y lnqulrles have been recelved by the Dlviston of Bulldlng Research from architects, bullding contractors, and building oumers regarding the causes anil treatment of d.ampness ln nasoilry walls fron raln penetra-tton. These inqulries, alon6 with exarolnatlons of nany builtlln6s by nembers of the staff of the Division, have indlcated that ratn leaka6e throu6h unlt masongr walls is a problem of con-slderable lnrportance trn manJr areas of Canada, as the llteralnre Lndlcates is the case in many other countries.
Many who have studleit the problen of raln penetration of unit masomy nalls have strressed that the, problen ls of constrderabl:e econonic inportance and of extensive occunrenee. Thus ln the ltrnited States Thornton ,(41) has noted, .'lleaky Inasonry walls have plagued the bulld.ing industry and bulLdlng owners for many ;rearstr, Copeland and Carlson (22) wrote that
rrleak;r masonry waIls perslst today as one of the:most per-plexlng problens in the constnrctj-on of nasonry stnrctureslf , erldr "Some of the fLnest buildlngs ha'rLng unit masonry bearlng or enclosing walls have leaked so badly a few nonths after conpletton that extensive waterproofi.n6'and repalrs ,wer€ Ii€-: qulred.tl'. , In,Connorts oplnion (fB), rfMoisture penetratlon through: wal1s above grad.e has been one of, the nosl; serious problems ln brctok masonry constnrctionrt.
fhe report of the Buil-di.ng Research Boa:id of Oreat Britaln (5O) in 1911 referryed. to this problem and noted,
ttlhe'problen of the exclusion of damp lron bulldlngs produces a verJr hearycorrespondence and tlr-ere ls every, justificatlon for the bellef that thls 1s one of ,the ,major d.ifficultles whioh artses ln ordlnary practtcerf.
r:', : It' has' been suggested by workers who :have stnrdled the problen 1n the Unlted States (11) that the problen has become
ecent tiure because of the lldlngsr use of thinner walls ; i n c r e a s e ' l n s p e e d o f c o n
-,' of bulldlng units and. cementln6 ,,.,,',,,,,,'.,. In the last thlrty years the problem has been
lnvestl-!ed. by mar\y workers, both ln the laboratory and ln the fleld, ct,..3lthough urany fastors have been found to have a bearin6 :,,ESp, Froblen there ls apparently not, yet eomplete agreement :r1,a,,Ll"iphases of lt.
- 2
I I .
l:Rai.:r TJater Tbrgugh Soroqg l{,asolr{ ,' h a c t l c a l l y a l } n u s o n r y u n i t s a l ! n o r t a r h a v e a p o r o u s
stnrcln:re
"o if,tt-itna"r
ttre-i-olces of caplllarity and' ex-terrral p""""uril*ri"".is aUfi-io-p"ss.tfrlouen: then' 3he tlme for water passage varies.Sd; "'tEw-*inutes-to hourq o1 days depencpng on-thE pe:meabilli} 6t-ifr" nateria] ancl' its thiclnsess' rt ls senerarlv asreecl (?, il
-";.iur-5gl-however
that where the:materlaLs a:ie of good siiau'il rs rare that they are pe:meable enou8lr that water-pJi""s through them during a iomal rain. '
Paluer (9) te'sted the 'perureabllity of g number' of : relativelv porous brlcks #; il;t;;;-bt
-!pprvine-?
-l l/8'lnch head of water to one std.e dr-tn.-il!9i*;1;-;"lt n6tin8'the tine
ioi wai"r
to #3":'i"til:l*"-tiil;;E*{*T:'}liiliiliil*
oinens"1"-ii-""dna;-to' e minutes''
lYhen
^::-
l*^;T?+:*:"
il[o]"fi:;*3?'33iii
.
rtion through
rate of water Penetre hls oPlnlon was that reachEd. in a brick be mortar. This degree
lras Pointed otrt '
however thai header I 'in:-thls 1-egard'
owing to the uricxs b gh the wa1} wlth no intelvening mortar Joint'
The above ev lealcY masonrY
wa}ls age not often '11ng- throu6h the
rnaterials thernselves ;s are \rery porous
and are la1d uP ln a as header brlcks;
2. Passage- of Rqtn riTater Th€gugh craclEg a4{ Opgin8l Ihe
z 6
rte 3e-0ary f ime lirs l s n e s s . e - 1
and. cLepressi.ons occurrlng examination of dismantled
by petrograPhic rnlcroscoPe
inr caBillary openlngs at the lnterfaoe betvleen. unrts-a raortar
""ilo"""i"in'a nuilUer of ways although-|!
1" not al-,..,,.i0i:ii"-"""y to tel} in the exarninatibn of a building or test
i.F;fi;l wfricfr faciori have had the most lnfluence in produclng them,
(r)
f l l v l l g v s v v v s v * ' $
-to form intj.nai;-anA couaptete bond over the whole surfaee of the unlt.
mortar ln
(11) T{orkmanshlP
Eoles ancl channels left bY filling of the joints are lmBortant nay result from faulty technique in ori carelessness.
III BRICK I,IASONRY BRICK I,IASONRY F-- CLAY A]lB _SF,A.IE BEI-C'K$ track of bo-4llqUryqqn unlt aqd--lugrtar rous :lnch tlme Ly 9 s frlhen s t . rlre and. b e iol,nlqg r b y rt wi.th t k $ , rtremelY k and ! t d ttr no
(iil) ryt"+TTlpi rqr::€
:
,Ehe :raln resistance of a masonry wall depends a1-s9 9n lts durablli.53'l-- liif""enttal volume eha4ges _causecl py noislUre or-tenperatur-e set, uP stress6s thet tenit' io d'estroy. the-,bond ana
"iiclc:the units ind mortaL. Sound'ation movery-ent" 9{ Apa*ion of .ufipfiorti"g
"tgg]work-rcin trave a sinilar
effsot. trrost aetlon o*-itt"riclt attack may cause disnrptlve^expansion
ii-iri"-Uri"l*"ir.
;nd result in crabtri, destruction bf bond',
or general d.eterloratlon of the wall. (iv1 FaultYj.esign detalls
fiashi$;;;il4-openin6s, parapets, oopin6" *$-spand'r€1 beans iE often the*caus6 of-leaks ln masonry wa11s.
at the iunction
buildings' tests on brickwork and
exanl-all support thls
unlts and
With some coroblnatlons of materlals, the nortar faiLs gfris can resuii 11.or the propertles of the unit. and
This can tresult l1'9t the propeX:fl-es or llle ullrl,.a& co*Ui""iion, aud to the nethofl of laylng the units.
the .mason clue to lnconPlete sources of }eakage. [heY laying the unlts, aeclilentt
Y AND SHAIE BRICKS
;he lous :ks '
1. Factors Affecting the
,,(n) Y,Iutual. sultalllitv-of materlgls
rii::::, In preced.ing parag.raphs it.was lndicated that lealcy
',,,,ppsorr.rv
*"ri" ui"-tii"1r . Ep"-
19q"1!
jI*:t""H: ^::d^:::1**9"*
4 ,naLn].Y
,,,..,.,1';,l$'e,:ciu1""i-tv-r"Jr.
or-r"riiar
contact, d'es-truetion of bond
,iiiii:i,1.: ious ioibes, or some d'ef ect in the workrnanship'
Bond Betrareen Sricks ancl Mortars
at tray by
( l i i )
workabllit
(iv) Illate5ials for norbars of hlgh vrater retaining capaclty
anrl worlcalbilit y--*G
I,[or-bars are rnad'e Prin<
of ihe ttilo.
Relationshlp betl,?een water retainlng eapacity and nortar
-)9 Proprietary masonry cemen,6s are also rrsed. irrs.bead of cenent and line, irut-are not stirclted' ln this report'
5
-the yrater retenti,vity of mortar h_e propertles gf t?re iine, ild--xuees mortar of high u,ratei
re-r sone nore-rtare-rs hleh ia,Bore-rtland .astlo linr-e. - Statrer e4) ob-.-,an be worked and. placeO lvittr parsons (26) found. that hlgh s gave rlleh water-retainln6: es gave .Low lvater_retalnin€
'i:,., his;'l.v
"{::lff.'
J19l H*}:d_9ut, r}qat gtly sood qualrty,
:
i',ii;',
hlehlv
pi."ii"'lil;; s1"y1g_d";";f;:,"-
fif;t"-ff3$
3:?:*-l{;rr"
+i,,,'
' water :retentrvryy,oi
fiIr3,tlT::::p:Tl::*-if-ab-p"iis*!i
:th"-ii;;:" ril"*;i{i8-J';:*T;i"rootir"
; I;;;*";;itri'oo, the
was also eonsLd,eied important.' l
uent sand :mortars are low ia ferryraan (6) stated that sand leltr gracled.. Anderees re-rsts that sancl should-be lress and. that there should rn qulte fine to coarse. I{e 'kab1e mortars are obtalned
^ t
l .
poor bond mey be caused by l_ tbelr water agalnst the
layer of mortai tn contaot rfore lt can,set properly.
;an bricks of a low Lnitlal 'or
thts was indicated by shorved. that the trhj.gher the
B
-t
healtnS of a tond layer
r\rrtlrer
"sd919",81',*ll
f$*?"i"ig",-lti*f"lt
waspres:,'e,:{!{:H"}?'",?1*fu
[3i.'.'ffi
..i.'a'?iffiili:t,1!p'
;1i!i"!ll#:1;;'iit'.tfi
[i[t'fl
"i3i#T'ltni:"uimi""t"i
.:;i"1iitl"'9"
n$k{l.rut?ttr:'rtffi
f tt#"lT:{"t#"pi'iil?ii"sauto*enous
( v 1 1 ) Desirabl-e u e s t wat_er retalql,ng 9a shoulcl'
ed that..no*?11
o'tf
ous,|^ll.ti.f;
"ti'?llt.?F?i*i'ii:1i"1"q":"itf;
caPacitY givlng ^ 5;-i.t 'r ir Of
9
-.ck absorptlon rates . HIgh l_lme contentecosni_?9d requirement tn"ltme_eeilent mortars does not aefi-n"-"i"rrf .y t:nC meanlng of the
a lime content
ar mixed. usi_ng dry-lty than a cement-anount of a more
.. ,in a fnortar is to iobably &ore satLs-,lne content as the ; wlf,l _glve the nortar rater than a speeifi;d 'rtar ,wlth flow
flow before suction hod outllned in ity. Palmer (1J) properties a mininum He conslderxed thls rs and users of of the results U/I St?ndard. Speclfi-,he minlutln flow I before suction. ) ( v i i t )
f br1ck absorptlon nt of bond, wltir --r-t for best sunner nch of water should elght of, the brlck (15) stated that rnd 10 per cent It f,avourabLe to
fhe rate of
ab-. for several hours.
A property of
llpfron
13_uiualiv-..
;laI rate of
ab-suctlon. It is tire 'l easure of br.Lck
by 3o square inches-oi d. in one nlnute
I g r a m s . ' t . . ' . r r . r . a f m o f t a l t i i ji i t : t ; r: i l . i L r i .
(. r -a*io.lr absorptlon *1 T:"il-.roatstl
l i , t:
The followlne
evid enee. regardine-t'te can be stated lnstrength aspects sunmary of the aboveof mortar bondl (a) !T+th high absorptlon
grve poor extent of .'bricks, _ straight cement nortars bond and lovrr UonO strengifr]- .q. hlgh p-rgp.ortlon of ffloe-jn' tire and a hlgh weter retentivilv
str_ength because of a tettbr
(c)
+t 2o'gr?ms abgorpti.on, ?ng- below,- the eitent of bonil
H"g?:3.i1^To:I-:::::
"1* Jl;.-!;+e #i"Sj!-'iu-*
vvrr
For an
1.2
ConnoT tn a d.lscussion of a paper by Palnel and Parsorts (Il ) stated tfrat- with very low absorption bri-c1s there is the posstbll1*ty that the bond- between brlek and mortar nay lol .. , ["-"" eood-in the'liefA as in tle !ap9ra!o1tr.1 Mortar !]at.is laid out'for sqtne. distancg qhead of the brlc}s 4a;,r s.egregate I"a1nl.{ur=coning to the suritac6 may prev,e.nt boird'.- Thls d'oes ilt ilil;n so rEadily ln l,aboratory wgr{ where the tlme
i;;"#;i'tufr"ur
siibaaine'{h"-*ortLr and laylns the brlck
ls shorber.
(x) E'ffect ofJettlng .bTtgbp on lond,streng.th
l \ [ a n y a u t h o r s ( 1 , 6 , 8 , \2, 2\, ?5t 77t.!? ) b.e]leve that cogsia-erable benefft fi t6 Ue gained by wetting 419!
absorptlon brlcks to reduoe thetr suction rate to a cLesiraDle ranSe
Fnom the work of PaLner and Parsous lt was fouud that the differenoe ln bond strengttr bettreBn brlcks cuitli absorptlon rates ranging fron 20 6rans to I
Althougb from previous cllssusslo ls impioved by-usl4g mortars of there ls the possibL1lty that re by vretting may Broduce evea 8r€ Foflcn.er et al, '$71 found with bricks of orlglnel relatlve
substantlally by adiustlng these before , layfug. Ttrey did find na1 relatlvely Low suction rate sbrength than brlcks of original to the sane 19vr value bY wetting.
?aImer and Hall (8) foul with hlehlY absorbent brlcks war 80 per cent sa1;urated and.'lovlegl absorptlon rate d ld not show st with some such units the bond sl Suoh a result would be t Palmer and. Parsons as Previousl ratlng a hl.gh abs.orption brlck 1 absorption to say 20 grams woilI( strengttr conslclerably with all would. lorner. the absorption rate
Sti€ht v'rettlng of a brick of :rooi reduelng.lt to 20 6ranns, would r bond strength. Wetting a brick about 15 granos woulct reduce lts a stlll lower value and result :
bond. :
Neurunan (6) warned a6atnr Cocle of Standarcl kactice CP li lf too much vrater ls usecl, brlcl bed and there may be d.ifficultY this is parttcularly lLlcely to I
- 1 1
, Collin (21) repor:bed, that there .ls no beneflclal' effeet from wettin6 bricks of moderate to lorry suctlon but a substantlal lncreaie ln bond strength can be. expecteil from wetting hieh absorption bricks. He obtalned data by wettin6
brlcks untll. they ltl fraA substantially'the sanq.'suction rate. Ilettlng appeared.- to have benbfLtect nortars yrj"th"hiSh cement contents qUite stri,klpglyr, No partlcular b€nefit resulted with the ielatively hleh llne nortar whlch lndlcated.:that
this nortar bonded we.lL wtth th Iatd d.ry anit the bond strengths tensile strength. In such a cas strength would. be expec,ted.. lVet
brlcks appe4rs to have been detrlmental ln sone cases. Pelner (13) stated. tbat
mortars sf ,such high vrater retal war:raot the general reooqqebdatt brlcks shortly before 1a3'1nU thu conclusiou. was based on'data whi
concluslon.as was d.lscuss.€d'1n the precedlng paragraph. With high, absorption briolcs and mortar rlch ,i.n ce4ent, wettln6.; ereatly'im-proved bond strength but with nortbrs rlch' 1n lfme : ttre stiengtfr was not naterially Lncreased, and, ln some cases was evgn red,uced., Certain masorury ce
d,isougsed in thls report siruilaz wlth hi.gh absorptton brlcks vrher:
lDre data also inilicated that wet brleks uras of no bdneflt and nay
llhe evldence that has been presented seems to lead' to the f,ollowing conolustons, relative to bond strength conslclera-t l o n g .
(a) Brlcks with moderate or low tnitial ra-be of absorption' should not be wetted,i
(b) Wetttrng brlcks of hlgh inltial rate of absorption ls lllcely to greatly'increase bond. strength where the ,. mortar ls low in water-retalning capaclt5'. llhere the 4o:rtar is highly water retentive (l eernent i 1 }lme:
6 sand., or rlcher ln Ilme)'the value of wetttng ls
ctoubtful; ,
(c) [he wettln8 of brlcks causes extra trouble and must be earefully controlled for the best results. In freezlng , ureatlrer it rs li.ke1y to be dangerous. llhe -r9la.t-ive.
beneficlal effects of wetting and the use of 'hlgh ltrater-retalnlng mortars shoulil be furtlieri lnvestigated
The value of vrettlng bricks, from the aspeot of water p e : m e a b i l i t y , w111 be discussed later in:th16:repoft.
_ 1 4
_ 1 5
I
i
t ,
I ,,::::i:'
mortar as the initial rate of absorption of the bricks 1n-creaseC the bonrL strength increased. so that the brlcks of highest,absorptlon rate gave the hi,ghest,strelgth. .It seems likely that mortar$ of such v'letness viould be lmpractical. io use ln actual bnicklayln8, but the above obsenratiotrs do
serve to poiat out the lmportanee of the tnetness of the mortar an-a tirat the effecf. of roortar consistency reQulres
further investigation.
(xi:.) Imporbance of bond strg.S!!
-It is important that the'bonct between brieks and mortars be strq4g bottt for strer
work. One orrght to be able, to J tensile bond strepgth can be,elq ln order, to set values for desl6 and other load-bearlng stnreturt lmportant that the extent of bor asf ect of durabl,l-Lty-Efpermea,l
mortar and. tre tensile strength te:mecL the tlbond efficiencyll, I from conbining several desirablt htgh sf,re4gth atrd. good extent o1 inportant. ' Data presentgd bY Pe richer,in lime than 1:I:6 Save E efflciencles as nortars hlgher i
brteks.having a lrid,e range of propqrties,. $h:is tndicates that. high l-lne mo:rtars tend to bond better to a'greater dlverslTy of bricks 'thaffircent morbars.
. : .
lhe results of tests on mortar bond bJ' PaLmer drrd
Parsons (1.2 ) show tha! with pu{e fitlg -rqortars the bond strengths d,o not va.rJ'over 4 v"llde ra4ge for dlffelent- briclES, llmes. or, absorptlqn rates. They ar€; ho';vever, uniformly relatlvelf
louu in strengtho
Irorr thetr results lt is evlclent that the bpnd strength for high cement mortar
to almost zero evs.n u.riih the san cU-tlons. lTith diff,erent bricks for this mortar only over a narl The high strength of the mortar the curve of ilecllning bonC strt absolption hlgher than about 30 'extent
of bonC ls good only over a smalJ rtrnge of suction r a t e s ,
From the work revietted i contairring a moclera-be quanttty c by volune do not give as large straight cemenb mor:bar el-ther utj the ran6e of absorption rates.
1 6
-tend.ency of the moderate fime nortars to produce .a greater
e x t e n t b f b o n d w i t h ' a L ] u n f t s - r : r : i : " ' ; : " : ' i i ; : .rt inch. to (xi.v) Eumroai.Y_ i:;;;: ,r
and nortar propeftle$ g.r.ive,the
'trio hes tr*66:' rsvr-rei'.red' because :Oas;a.t ihe 6rnck'ancl rnortar
.arg6 ;ettent ;,for,: rnhsorry, : lealrage ; len :revlevled r" : plartly.'because l,t
of masonf$,:naterialls, anci aLso larch'has ,'been dCvo.tecl' to the leeh :cleS'igned speciftcell..v:' t,o' I 'bhe avai.lable: 'lnforrtation has
tests. Str.gngth of bon{ and col
w h l c h h b s a l s o b e e n ' d t s c u s g e c l , n , , e abillty of bon.d end bpicl;wor'li :1r
_ L 7
:phnr.e1s:,'5qt jSerce,b,rXok panels'fr-ere ino-tu<i.ed.
Drtelwvork
,, ,1,, ,,.,, .,..: :. I - general r: the: higher the :brlefi: .suction rate tbe
,:,:greafier rras the.'leakage but the rate of, transmission nras
:,,,,d-$mihlshed.,rif' norta.ri,of,,htgh t:uaf,sr;astg,ining capacliy andwater.r€tg,ining ne rate or xransmrsslon Flascapacliy qnd.
lflOlv,,vrasi:used,.,'r,fhi-s was plitlculatly tn.-e ior hrry p6rous
rou,gh surfaced. brlcks lairl dry. l.'iith all bricks. of hj.gh
aspof:pt-lon, the Brea:test'redustlon i.n leaka6e v''as op-talned
lredlrclne:,:the',suot:Lon rate t6 a loul val-ue by wetl,lns the
"1e,.du.ctng t-tre suotj.on rate t6 a lsn,.value by wetl,lng the
Sri;eks imnie,tttateilv: before layine. teily'r o. efo:ce laytng,r :
hlgh,
or by
(:,21) tested masons-y panels hiciqlesses by- 'blornilng wator an'air d.uct and noting the veloctrty usgd. fo; nost tests thoughtl':to represent about rithe
maxinum-;, oonditlon," of conti.nuous .hea115r,raln,rfi1.th high'' wind
'althoti6h
not, neoessari'l;r ,the exact eclulvalent : of ,natural
gohd.itlovlg,. : :iTes:tS were raade pl'tncipally' on eoncrete masonly
1 8
-One of tn-elr concluSXons, WAs that mortar workabltrlty
and walli-$erf6r*A[.4.E
,WAi-6'ifr'$;'['e6.a,,pV'rusr4e:mort31s
:contaLnj-ns
hieh quaLity 11ne.: ,In thls ie6ar{ dry,hy$rated lime was
JiE{u.i .1o-=u-e
i[e'BooreSt;:' qui6fri-friie :pirttg:,!he b_e-st.
and, p
stiteA' !g::: 6t the poolcgst, q:Uidlil-loe' putty,:::the'
best'and,Fre-"oar<ea
:hl1lraled,,;rine'
:,bt interalldalater,ogalltv.. l{oTl1Tg,:9?:
C O D - ' ,t"iiii"S."i'.lai*-orbfiEh+,'-+a.-[
rii' ,paitl'.Uqdg,
:p+u- presoaked
lildrate
or, qu16h11ile putty:'bquai ,io.',2$;',lperleent 'of ,fhe ceroent v'olqpe or oulckllde putty,equa.L,.to'2'5':per eent'of the celnenf vorqme
had:equal' or t,ettbr,r@en irete*ltvtty.than pure trime no:rtaTs
lllot more,i than' 25: Pe;r. :
:
l l
Good (G,) '
Fal-r (P)'
waC,,darup at:;,,th,r€,' end throu$ : the'Wa11,,, in'
on b'aok.,,of 'tl]e ,wall ,at,'..., '
,Iresg tr1rgn: tO.per gent
damp at' the ieddr' of'.1':d,aY;.
the-waIl.,4t,,tiie.end ,of , ,,.i ,
-':,lryater, vlstbl,e on back',of waLl in,'5 hours '
' orc,",lesg: than 24 hburs.. Rgte''of leakage,'
Iesis- tharr I U-tie per hour at the end'of '
, 1 , , d a y . ?oor (P) ,
: ' ' : : , '
Veryr Poor (VP)
, The following oUserstat:
effect of the brlck and. mortar
of brLck, wal-lS. ALl, u.ialtrs tha't
_ L g _
Filling .: of joints di-d not, howe'
or tlexcellentrl pgrformanges unl
sorption,:v'ras ,Ies:s than 10 to : 2
thfcknesg i6nd: the kind of na er
ratedi,ligoodtl :or'ltbieellentli' urhen the brlelc suct,ion d.id'; not ',,
eieeeA fO, eraue., 'gvve,X$e-i.nch,waLls:vtere ltgood,lf vrhen ther,, briek
iuction,.avE:raged,,,ab6fi,t.,,20,:gians';',, .,T[al}s were hlshly ,perm$able
w}ren:t}.'.'.b"-i."H.'.suction..,exo.ee'deti5o$i'ams.;
: , l'rlatr}s of :frtghly absorptivg '-bqlglrs and nortar of ,s+eh
vsater' rotenti.vity:,were,,better'*h,gn,'walls, of ' the. same : qualtty'
briCkS bu.t,wi.ttr :,tory':watPr:.rete1
ltrne had h:l8h, ptrasttr'etrty,,it, wai
arnEunts: qf,:.,l.1ue r,ARd :cjement,'dfc[
the noritsg,a's: loRg,,gs,,,the :,fIol
particularly true,,f,or ;,htgh suc'
. .
' Tpsts wlth brLcks
loner the absorptl,on, rate pe:meab3.9 :ttre naSonry'.:: :
., ','.'i, ,McBunaey, Copeland and Brlnk (,J.1) tesled::a.sgrj,es of
sunali 'masoi.lry,,pairefsl tn,a mallner ,slnj"lar 'tO that of Palner
and Pa:rssns iii). trnoludeci tn tles,testq were,brioks of:ten
dlfferent iates of absorptton: as well'as three morbal ml.xes,
1 : f i , 5 , ' 1 : 1 ; 5 a n d 1 : 2 : $ ' . ' S o m e b r l c k s w e r e ' } e : ! ; d w e t a s w e l l '
as:alf , th6 Llme used-for all tests vias; a hteh caLciutu quicklime"
:: Regardi4g the effect of, briclc and nortar properties on
panel perraeabllittes, the tests'sholved that the difference in
brisks: had.. much more ef,fect on
f,erences ,i,n the mortars. 0n1y
,of absorpt:ion rate less than L0 gave no danpness or leakage a:f-t b:rioks leld wlth l:1:5 and I:Z:i
and sonte leakage. lfLris tras attr
nbabllLt1f :of t[e morbars themselves, and,to ehannels at the
bliiclc anh mortar lnterfacCs. lUost of the channels appeared
at the verbical joints but their presence was not explalned'
A1L of,the panels:of brieks with absonption rate Srqater t h a n 2 6 g r a l n s 8 a v e 1 e a k a g e o r d a m p n e s s r e g a r d 1 e s s , - o f t h 9
mortar u5ed.. fhe rate.oi Lea[a6e-increased vrith the rate of
absorBtlon of the brlcks but l.'as reduced sone"rlhat by using
rnortar of hlgh water retentj,vl-by. '
The decrease in pernoeabillty with high absorption
(inltial rate of absorptlon greater than 26 g1ary9)
l;he use of mortars witfr higher water-retentivity
rryetted,,befor€,:,ugre, sbioited., t!4t' the
at,the tlne of laYing' the 16ss '..
i::l:::r'l: : . t i + : : i : ; 1 .
brlcks throu6h
__
i.
I
- 2 0 .
was not as great as th.a'b effected by rvetling,,Urr-e ?T)"I? to red,uce thelr aUsoiption rates :'',:4tn; used lvith T.*i| lor-tqr, Uri"t" of mediurn ina ftieh iates,,Of, absorption,. t'rg!!e{before i"Ving, 6ave rnuoh red,rlcedl, be:rmeab-tr1j-ty,: cbrnpared' v';lth t5e
saille bricks laid :clrY. .
after test thatIt was fgund from examxnallon,ofi the_d.isrsentledst that thoSe benols"'$rhio?ii:' ga+e no ileelcage l'rere penbls'" nulrish: Sgve no ileelcage.lr,er9
panels
inai6cteii"*a ny neqiri;, pegrec1,u,,ona:b_6ture9n.Ihq,
!fl:k-t*
Chaftfgtefize6t by negfl;r, peIIeCE OOng' De6lrqen ullti rrrrurr :cirru
;;i6;; :Piners- t;hat lbafted haa bitbnnets q'b the brick:moritar
j-ni':.;i'ilaees, generally ln'the +erttcal {olntsl -M'jil s'orle: very
;ii.tr,,,* trricirE the "waier aubeaie'* to,pbss :rCadtrly through the
pCIrous briclts ttre waterrappeere pbss :rCadll-Y ,through the
b r i c k , ,
(a) ntre , lnLtiai ,;rate of absor-ptton
effests on,the.; ' pesueao*trlities :
:of. the brioks ancl:the mortars had.lmPortant o f , t h e , t e s t Banels,;'
(b)l ,.the lnltial ratUrof absorpti.on of the b::icks hacl the
greatest effbctt
(c) fne uost wabertight_pqnels were obtained. rvlth bricks : ' having a v;ry 10fr abssrption ra'be: l.C grams'or }ess; (<1) The pe:r.reabi1ltl.es of the
creasi;rg absorPti-on fates
panels lncreaseii vrlth
ln-of the 'bricics;
(e)rFor the yange of absorptiop 1qfes-bett'reen 10 and' 25
gralns ttre e-Itect on peinreablllty dgeP not.qeettc !9 b*
frelf' established. and- d.epends sornervhat on the 'vrall'
th.ichregs (ura],l thlelone3s ls cllscussed in a later s e c t i o n ) ;
(f) Above 25 grams (g) l'flth brlcks of
the uraLls was retentlvitYt
all rrralls r,ver',b very permeable;
high suctlon rate the pernreability of
aecleased by usln6 rnortar of high water
' ' . :
i:::i::.i : i : i : i i : : : i : i . : :
2 l
-: r r -: . . -: , 1 'i:: :
: : ' . . ' ' . . 1 r r ' } ' ' ' T h e . : : ' q u a 1 j . t y . . o f t 1 t e } { r n e . a p p 9 a r e - d . : b o - b e ' . $ o r 9 . , 1 m p o r t a n t
', , ' I than:;the airount of }ime used. Highfy plastlc quick- :,
presoaked ,hydrates next best ,', rrest I
ricks the l.qast peruteable uual]s :r-ceroeut lot{-lime mortans,Fro-ls a:good. qual.itY Plastic lime;
: : .
sorption, rates !?al-tr permgabillty
,L'.1etttng, thb bricks j-minediate1y
. : .
T_eslg
F ' . . . . : : r : ; : i : t : ' ' : . ' i : :
r-.reir gi:eate:l impriovenent is rl
:iqlcs*before,e ]afing to' reduce, :
v-aLue; :: .: : ' :: ,
rth on the exteni and qqalltY
' L O O per gent in all cases'
best results for absorPtX,on
bonded. areas ?rere left :'i;o glve r: facts i.ndicate that bond s'trengt
fOr extent of bond or watertlghtness of brLch'tl'torir.
Fo:r bricits ln the ilorry at good extenb of boud anC ze::o 1ee
obtairred, Cire besi results have
lmpervibus bricks of 2 oY J gran lvi?uh ,the. stz'ength. tests'v-'iherr'; cc
obtalneC with glassy bricks. AlI investigator:s have, noted., holveverr:: that: :l'U. qhS: difftoult':to, lay suCh tnpelrmeable brlcks. The brlclts tended,,to' float rtitli h,lgh v'rater'-retalning mor'6ars and "r,hbre''!Tas'exC'e,ssive. : o.-le,e<ling,of ;:bhe mortargi'when the w'a'uer-re-balniirg cbp.aeity. l'ras ,Io1i. ,, Palmer and Peisons noted' frors their olvn vu0:cl<:rthat the,brioks lvere Laitl in the wal-lettes
lI$ , be, :fo:1.1o:uled. .b;r masons ' 011,,,,.'ut 'the,,nortar - n'.ric]r at a: time lvhereas
otrt f,or several d:,: tr5611',,'1tTgo:rk,,ulas done as rapidly untegt between,the hiShlY
porous.;briblrs "and,pOrtarS ::of,,r.:ilorii',:,:trater-r.etainlng ,capdclty and.
,e I tendeney: of, [orv;r reten'biuity .t6hef ,:rve{'er retentivlty. woulrd ,
ltatG',,:ther.:':f ill'irlg' of , verti;cal' a' tfre;,r.,'csns.lclered : that': lnbxtars _r'rOUL C,l, gtVe, better vr0:rtlmaniShtp
were besd for: :l"mpervionETffifiilAfia:S,E-Ai eernent mor:tars b they,,ttrot€trt that,,f,or;:f,1elld:,,c6ndi't16-n:S'; *'x-re ,the.'worlrirr6
and , therefbre le$s ,;;X,aaliAge 'wi*h,;,,loal',,;;a-bsorpti.gh . br:i.oks. : :
Oorulos (X7) ifound that bricks':havtng: rates of ab-sorp'bion IeSs,'than; l, gqam-s :gave,high :per-Centa6es'of cnacl sorp-Eaon f ess 'Tnan, );,$T€Ffl-s :6ave :ntrgl] pel'ceDTa6es or era between brichs and.;g.r$i mortars an{tr he belleved that the differeace o*etwe:sn: :|shoiatory 'Ffbced.ures . end^, fl6Id prac
f cnacks ed.ures 4n{, fleld. priactlce
1 , ,
I I
i,
re ob;taine<l:in laboratory ' -ned tn pfaqtlce. - Iie flso rryas tf;e ,lzas,used. :j.n laboratarX,,
glve good adhesion :betrveen t6r'tars of ,19,'u rr.'ater retentlvity. rsually be given the bric}.s ln lug$t that brie.lrs in tlte lebora--n 'the:'fi-eld:so thbt even
r1d ha''.re t-heir na'o,funuro airsorption tency to ffoat. Connort s
ti{ith an absorp-blon rate of rtly Broduced. less eracking
his opinion brlcks of rnoCerate .n t-,;ater that' petretra'r;eg ntnor Ured.. l?ith irape::vlous brichs, lcli)-y througlr the i.ral'l if there ig sorae s1J-$hi defec'U i-n l*lorl',manship.
lil"', mi.ri:-nrurn ,,:r, , of limc
'?e1rlrer
ancl, Parsons (11) noted tir.et' 'l n their tests best resrrlts li:ere obtai necl r.rith snoc'bh :impervi.ous' bricits sei dry anci sraootijr: porous brj.olt:s set li"et ','.iheu 'uhe norte,::s,t'rere high 1n: cemenl; anci lc'l in Jine. They consj.dered hor'.iever the.-b ririth rough bri.clrs the nor'uar should be nore trorkable.
Vcss (15) believecl:that briclis should have a cer'uain sric'bion re.-be l';hich l'.ould. d.rel'.t the fine corrstituents to tlre br:ici,: erncl tnor-bar inte::face ancl titt-is fi]l roughnesses in the brj-cii.
- 2 1
I , ', . :,tr.*j-shbu* 11O,) ;noted that: where Low wtite.lr retehtivtrty
mottars rvere used Wi.th briclcs of }orry absorptton rate the laying of the bflcl{b rvas marlied bJr,excesstve b}eedtng o,f water,from
the mortar oi extmsion of mOrtPrr f.rom the jOint; lovr
absorp-tiqn,,,bnfbks, laicl' ,with"high watei: retalnlng mortar were laid
wlthout,diffi:eulty .
' 'Shu above dlseusston Lndlcates that the use of brieks
, may gtve unoer:taln nesrelts,ri,ll ,
;ks shpuld. haVe 'a, nini.ra;rn l
tten :', {n upper, }iait ''bo .'51t* , '
:Iy'eet at about 25 Braios ,
ris' and. pievious sectiong; ,
-n a fater section, '
, , ,
'
: i : :
:: 4' ': 'Elffect of,;:otherr Brlek'PrO.l es orl in Resl,stance
I . : .
le slmllar characteristlcs ,' :'
rrciing the rel,atlve,water
rcteclYof .brlcks',:tneOe of , rllfferent bhods .
$7) founcl that,bflcks nrade
rri.als gave varyi-ng tensLon ,
bypes stuclied', the stiff-nud
rcnd stren6th 'foflolved bY,, :
LaX: Piie, relative iesultgr
[he : rpughness,',oi ,tfie brtcit' :
r :the other:hand, fbuncl that Ln the strengt.L-r',and durabillty res stud.ied by them. Coruror (17)
rservations there was no certai'n
turface-cIay brlck having a
of absorptl.on trould not gi.ve . wlth the proper mortar.
:
eiaclis ln':brlcks. substantially i"ncreased. the amount of leakage
through briclt ancl mortar assemblages. :TheS stated thgt it :
ts'de6lrdble that brlclcs be free <if cracks and unusual su:rfaoe
:Lrregulaiities and be of unLform slze ancl shape. Butteiiivorth'
(45)-dosCribed cer-bain materlals end conditions of manufacture' that, are apt to produce the higfoest incidence of craclced or ' deforned bricks
I
I
l,
_ 2 + _
,
(ri) 44e elrect,g{, ffpn-q e'19 gPFgFi ,, ,
j : r ' : '_ :^
i n s t e a d ' o f
$oue brxsks ,are, fg4ed rrtfr!.flotgg
or 19T:: :
- f a o e s ' r r i ' t h ' t h e s t a t e d . ' p u ' T g o s g o f * ' i n c r e a s l n g . t h e m e c h a n l , c a l
.a*r*a.rl lrri .k and. nortar ,anrl ars6-.ti'";;4il; Er'e tendertcy
a r b e e l ; " ' : :
uo:,no :nuctl evtdenCg in f,avour of
I solid bri+ck faces: ' ',
rils '
'' Bond sirength ls not' hovrever' "* Rb:-913te criterion
,, ,,: ,, of extent of boncl
u"a iiiii";e"i;il;;;:
-i'i*B'trn"v
I
, , - 2 5 ;
{t
I used 1n hls tes.bs the
' ' : : :
: r . : : : . :
tn*tiar;'rate. of ..ap,s9.rption
of'.$ri'cx5'irtaa-the :sreu*e-"i*a-rfect
,$i,Ery"tY,:r $.e to"-rai
=-irnsE'
oi-sii*ti'Jo:',
rut*u rhere *eii=" "
E.ggs
:ptfig t$e, _ :r.qsge,
,os :desrragie_nri"[.",""tioa-
izij-il .zS
EF4lls-:oi.b$Iow),,r'1here'veitatlons t n f eitag;e: seemea to r U.'e
91ry]1,rned
h{ :d+fr-g{encg.q,,ia
,r6ushnes,$,1,,of=dhe-bilefer-'
,fop"rr-&eht$ 'tsrg]ie dbsi:erieil '*naa{'${,rin1:1 r-;r +^ 'i .t -;+^*-r-{ -A+^ ar^ -.
spe,btal tebts indi.sated. that ,water can,be d.raw:a alonE
u ::* lf^ ".lli*I !f _ $tt'y? s e?li " g- " i o"E"e "
-l.ph
iiir,?y u
th e:,
s'rri 6 u' " i . ", uf i,p r- r_:!-;"+;
:i,$";" i'i ;E'-",
ifi I"! 8
"
"13ff
,
*31{F_.ir13n$ea
nri-[{ ;h";;a ty,il ;f;;;; rouch
nore rhan
-Dge;sllrlace
of-a, bgl.ek by whgt rras eall-6d tlsurfa"" *apit,f"r,if5rtt.
Rough or sanded brieks
"iioi"ea this
pffanr rnirzrh yii;?^ +t^*
:Il:F:_tgt_.u'e:re
g,pooi:r
_-urt
otrreCriJ;-"i"iiJ:'"ii:#i,*ll;'
o*,-j$iou of , ]h,e authors the'r wrren
I moit#-t; . pibo
",i
-rrr*Io*f'Jot
ytl:bh A fOURh briok thet wn*ay ic Ayarn* rr.n--{;a.i.r-:r.r: ^r---
!r-l"{ltt. a roush brick tiret yrater is drarvn-n6rriJnt"irF-,i;;;-;d"
|nleSfece;a4d sprea4: out:ou the verticar-Lxterior ou the vertical exterior iace of thiefeae,nr f,l-e
Ilg=pj?l? 6f...o?+tacr
rr,litrr
tiru orier {rr^-t:lo;A ;;"+:5;-i{
prevented. Ii/e!!l"g
?r lgus+ br:tcks "''a-tfiu-o";-;i;iailfy
retentlve mortars ieduceA -ttiis erieeEl
--l3str teqts rndieate that even nhen r,-rre initiar rate
M-Ft" ar* ?p.r..
to be obtainea'aue
io-iiri;;;;;*fi;i";;
fi;ilJii'f;3"lt rected
- h n z l o s ^ * J . . i . ^ { - - & '
-ll_ *:i":gill's, .ur,e_
suirace
_
t;fr;;"" Tilt iil;i#"iinu "[""t
cohdl'bron'for complete bond ano it-titu-"*"" time sufflclent
mechanical key foi strength.
5 ,
( 1 )
: .L,Iost authorltles (1r. 6,
that the nost importanu facibor I?orlsnanshiD
- - - - .
i n .
T,mportance of Eqrlaransir.in in r.ra1l ablIl
1 6 , 2 3 , 2 5 ,
- 2 6
of irrick lnralls is the 1",:orjerrutushrp. '!nhe ;berrn a.S i.L.l" ."?tpo*ly "S"A'"pplies brickg- are laid but also not c,nty.'to :bhe car6' anil rtochnlqye.wi-bh t'"'hicir the-Uo certaj-n fac:bo;:s -bha'i; are ?
-stif
"tty spbaking, pa.rt,:of : tlte r.vall des{.-gn specifica-bioris but l.,ririclr depend on tlie bz-Iclflayer. f.or.pr€per. exegu-Taon.
( il ) Fr.lliq&..of. .'ilt:Littg
Bricirs are often ilaid ,l the verti-c:rl join'os ltiruttered.ll l so :tha-b i.rithln the .vell, tlleJl:, : el
. i : : . . : . . . j :
' 1 1 , ' } 5 ; ' I , 6 : r . ' 4 0 ; l ' 2 5 r ' . 5 0 ) ; a g r e e J. be :sollGlY itill.ed to aehiev.e e:$ts, bf ',Fi,siCbnrn and co'-r'lol1.;er:s
coinpletefy filled 'general,l.y - Sq-r resistanc,es. +ad d.iff ern'rt lcin<ls
relativefXl nlnor effeets in inc;
of uia-ber penetra'cion; :
( i i i ) . ' ' ' . .
In rone tecbnique of briek laying 1;he nrorJ3r -iq si:read al-ong ttre Uea'by Le.vljig. ,lt along the bricks an'd .ihen ff;r1.9tr'iing it niitit,-the poilt oi t6e trov;e}. This is dcae !o spee<i ihg lvork and als6 , in cerrtaiir eases to make it ea,sier t': set-ble the brieks tbo line and leve}.
vra.tertightness"Xncf streti6'i;h of bricll waLlu. Fishburn t'|Ol , on: the other'hand, statecl'that
observed, in,:the penaeahility. of for the beci joini;s vaae 1erre11ed
bricks, sufftcient nortar havin
Llthor;gh the evj-d.ence i s li.rco;rclusive rega:cdir:g
furroraii{-i""[Eitti+oj ls o-r the opLirioS t]ra.-b ii; ilcresses the F;;ibttf'Uy of t:.*a..iine volds au<l ciiennels tlrroitgh '"ririch rrater roay penet:rate.
(iv) TqP"eU
4sss
,
d- on the noriar bed, theY :ar€: ': , em to ]ine antl let-el' ,4n'dglegS' '-6tii:rt "1nto ple'ce brealcs . tltg' ' ,fre mortar . anrl- tirat; lhe e'x'Lent ' -':: : e-ott'trtu tensth of tline Tlqt.t'he ; ,;i"S enA on tfre i-ra1;er-rretatni-n5 ,,
r+l: ' Uulg
It ha.s
previousLv
been 19t:-t-tf:-*:.Hli1lt?ilt35;
I t h a ' s p r e v ] - o u S } J u c i i e . e i a u 1 y : i n a i i v q n c e 'the rsort;; [ed- is rreqq-eit]y.laid,9]i,^3e"1, *r.o rnn"'rar,tosi.rl*;:i, ::
:?
" tflyf;
I' 3f;
t"i i$i]. ffJJli"
i i- i ^' git;. *i *I:".T;,;'T*'
iltfl ,,
fi
5*.lni"til:.t;{1ffi
' o.,tt;il i; ?"-!i;?!-U'-l:
-"1*:
"*}futii1+*'',
"
'rr;i; :
: r ' ' r : : : : . . r . i . . r 4
: i a r:
2 8
-to fill the i-nclen:bations arrrl r
Thornton (+1) thought that thj and recommended that short mor preselve the noi;stv.::e,:itt, tlre ii
i m p e r v i o r r s m o r t a r b o a r . c l s : s h o u 1 d ' : . f o g . ' ; u s g ' d . . . . '
(vii) ifolnt thicknessi , i .' ,
% : i
nes$ ls,.lmpOrtant,, $n::,,securx4$,,a; a$r) tooi tlri.ck 1t':{s ,necessary ti
r'vorhirrg urortar, surj. :'.regJ, llntle
moriar, so, that thei contaet ls :
p rou,t' of, ihe ilertical jctnts,
molstul:e readl.i;r 'Bassosi'" ' ,
anc[ more Fia'Eer rests'cant then thlck :q]r€s. , Es f,owd. that f,hl-ck
jolnts eausecl trouble orif irt,g to saggi:ffi sf the noria:r
,neeessi-t a ' ,neeessi-t i n g ,neeessi-t h e . u s . e - o f : ' i a n . . e x c . e e s J . v e l f l . : d I y ' . . . . B x T . . . '
i6, Ail generall.y agree: thau,; ;reateot resistanoe to rain
r ar:d Pe'eons {26) leqttd 'b};at
;ooletl ;olnts, v,iet'e Iese pe:rineatrle
r-bs btyb th'aip, joi.n:b toOllng ','Ja$
,Ilip j-nside tha wall"
t . :
'
Counoi'(rgl :iolraa froct a lar6e nnnber of buildings .
stud-ied. i;liat concaa:e tooting of rnor-ba=' cinl;s i''ras a highly
favouiao*lo factcll fot- rein reslstaac:e of brlck rralls' : Hq
al-so formed ihe opln:-on 'uhaf f1ai-'i;oo1ed, rou6h-e-ut or rakocl
morbar joln'r;s werE : d.er.{,:--*1.rnen'otaL facto.}'s.
.And-e::egg (2t ste.ted. ih.at 'che roolii:g of : joir:ts assi..sts.
greatl;r in br:l,aglng tl:e nori;a,r and. brj.olig j,t'Go inbinate ccrrtact
but ,that it shoul-d not be clone beforer,the riror/r;ar has stiffened
enougfu to hold its sha3re" [holtrton (45) also thougiri; -b]:at the
tJne efenent ful toolil?g rrf;s liepoiteat:ap-d thai tt 'orol<e the,
bond v";hen cione too soon. ( v l l i )
Accortling to Ner.irnsm (6) cut-flush and ralled joln:bs are
so diffJ-Cul-t to cons''cruct properly thal; he recor.iine:rded thai;
they rro'c be used fcr bUild.in{js accessibi-e -bo 1's14fl-dr;iven rat.in.
l
face, ,Of fhe,wn:Lll,r,:;tbetreby-i:,reduetng the p:cobabllLtSr of :ht-ild'en ' :
: : . : . l j
(,{x}:, 'wortroAushrD: as'"a'.,ffill'atigs,. :o{; tbe;''materlalg "il
'
, fffgh watei.retainln8 oq.pqcity,ls usually- ,agsociateil wlth highiithe oontent gpdz:aacbietrrg to Staley, hlg11 1-lne mortar aan be easllY
ltorked-: (19) also emPhaslzecl the i rbtalnlng workable mortars. rl.fo:rrly=ggaded from eoarse to Itars. Mortans contalnl'ng I to bo harsh;
(x) Mlxtng of nortar ngterLals
f mortar, And,ere ES $\ -rrrn ancl'in1,lmate mLx of the l mechanlcal utxer shouLd be LxLng ls'done bY haqd' lhe gnera-nethlng other 'than a. shovel
IVewman (6) bellqvecl that mortar often sh'ows a-lack of homoeen"Gt i"'trre mixtrrre--and that the.usual practlgq of
;i"'iil-;oi*"""
rri t .or: z nlnutos ls scarcely lo+e eno9sh. - _ _
iiiil;fitioi,
slated,that,,'gl'eater workablllty and lnperylousness
1 0
-can resuL'b from l"onger nrixln6.
6. ty_"1l,Pqgrru;B€l+t#,
: [o 'obtaln a rein-resistant brick,t''ralf attenti.on'nust pald not: OnJ-y, tO {he probl,ern :6f'l,obtbintng imporvlous brio
be pald not: onl-y,to {he probl,ern:6f ,obtbintng inporvlous brtoks
and mortar',iofnts,, bu,t,,also tq dQ,siAr delatl.,s 9f tlie ruglJ: such
( 1 ) l v
fqierS';'arid,flashtngsi She
'af.ufe," contairr the, observations
rii,orrs eutho$tl"es have , nade',of
n6 Leboratory test-s.
rnel-b, nb$e bY Elshburtt; ,lllatstel"n
rat:,.:rt'f ' frJre [rrteftor,'Jotnts, of
;hi br, :,and ll?.,:tnc'lr :,lnrbe6pa3- :
ll-p 'jtO ita:beyend,';''the-fej'wAS nO ,
;he : abs.orptive propertl"es" of ,
great care Ls necessary: to ensJur
j o t n t s ' ' : ' . ' : ' . ' i : ' i . . . : : . . . . :
,:IIa-e above'r oorrcLusion$,sre Ln eg:reeicent r'.it''bh ih.e
milar jdest resuir\s Copelarrd
where the ltor3niiensbtp was poor ;age ii:. a L2-inch 'rryail ot'er an "
0onnor (fB), fieon hls stucly of be'Lclc b$.i.!dings d.e-' '
ternlned, that for reln-resisiailt T'r'a11.$ e. nt:r:irber cf favourable
faetors must be pr'esent in the brioir end uarter. proi)or"ci,es. ron'he f,cund :'blte.t a.'I2-insh :
listr.:='e reqlstasce f,or in-uegrail
i -blriclcrerss lee.ited. lqhen un-, [n a]-J.r the huil<iings: studied ified bu'b'ecoordi-ng' to 'the'
e:rfectiy th-is ?ind- been d.one. It
v,ras apperent that :raLL thiekaess alorre r';ouLd. ino'b ensure
water-tightness. : .
' '
(111 IIE?dof- bFp.-clqg ': , ,
, . : ,
.r.. ' ?"Irrrer and'Parsons (?) and Fishburn (30) found that
wheie the briclcs yrere hlgtr$l .absarptive, header brloks lncnease.d
I
l:::::,i::: rr':r: :
: j j i . : : : : r
,ck v'ia}.l-s by p::ovidtn6:a dlreet ,nd ouier faces of the lvallt uch wall were bond.ed. together rder :llrielis FLshburh observed' r of: ,hi6h a,hsorp'bion br1ck, t'{as uboorpt.ioa ,:bricks there was rothorls of bondirlg.
i
;helre. uaas ,lt3 evideucd- to . lr-holfow unlt as baclc-uP for ( t l i )
of the walls at a'Io',te:r ef.evetion so that ?ot as 1?rS9,?1 arga of, ,thq -r'latrI became :'d-amP
t l 1 e . . i ' : ' . ' . ' ' ' , . . : l : : .
id. briok i^ralls glve sltghtlY n ro'alils wlth backings of
nterio:r iolnts and a relatlvely ference is not likelY to be greatO
(1v) Parsl'
a pargi.ng 1/8 to t lnch thlcl< of the f,aclng lvy'bhe or to the was left be-bween the Pargi.n6 Panels were bullt ln thls vraY
tests on masoffiy pallels in whl--c,h nas applied eitfrer to the back back-uP r'qd;he. A narrotl , sp?,ce and. the:brick in the next wYthe" havin8 hollorv unlts- as baclcing
' Both WPes of waI1 wetre as vri'th 'Ehe slile const]flictlon
. ! i i . : .
3 2
-blghly reslstant to wa'ber penetretlon even though t4u Jolnts
ln-the lnter,lor were not comp'}etely f,llleclr provtdo{ that so}Ld
Jolnts were provlded at the header brLok courses. The parglng
froved, to be-most effeottve.nhe11,,:appllett to tho front face of
ttre back-up wythe, Bi.elrt.tnah wariS of thlg tyP-e wgre Fgr-o
Bemeable howbver, than strmllar:B;i.nch solld. wallq tn yhlclt
the vertloal- jolnis (head and. cOLlar iotnts) were oonplo'bely
ftlled. ,
(v) nlrrumlugps
'w,qi.gq,Qa{#€g
,
Shaw (2O) conduqted'tests ,on-tr6- by.'If,-$oh brlck
walle'Utes, I Lnah€s thioic', ,by tnpounitlng a 4-in9h head of '
water on 6ne faee, .Oue ,w{i1l-,constlireted by fiill4g the sBace
betlreen tvro y,ra}trs each Of stngle 'brl.ek thlctsoess wlth ,a "hot rrqda.'buxrdI:+8..ootrtrtgst'tlorrsgaveno1eaka6oordam.1ry.t-esg.
, Arrd.eregg (f ) suggested us*:rg a4,aepbqlt dam petween the wythes of ,a:wall but ln a later paperr{2} stated"that tests- had shown,,.thlS.,neth6d O be,,,On-lylmodscately 1ef,f,qctLve'
tn preventing leakage. : ::
. ' ' ' ' ' ' ' . : ' . ; ' ' ' ' . . . ' ' . . ' ' ' .
(rri ) ImBenrlous vs, absorTtlve wqLl , , ,
: i
.vely high but clecreases
i. ,f,trls lni.tlal h18h, absorptlon
rqn refe:ripg to brlclrs. After
,e lnore slowly and for sone lace :lt nay ta1ce,, a matter of , Ilntll the blt,olc ls saturated
hs water ls dram ln as a result of the caplll-ary action of
the unfiLled pores. Tlhen the brtck becomes saturated'
captl"-lary foroes are no longer present and tbe water w1ll flow through the bri.ck und.er extenael forces suc,h as vrrind pressure
at a rate determlnecl by their satarrated peru-eablIlty.
Ral:r falJ-tng on a dlry porous brlck wall ls llkely to
be totally absorbecl for t]re flrst few ml.nutes. After the
prel-tnlnary suctlon stage, !f the raln ls,lrearry or perslst^ent.
the ralnfatt nay exoeed-the rate of absorptlon so-tbat mueh of
the water runs dorn and off the wall. Such a waill nay be
leak, free on the lnstile for a oonsld.erabLe Berdod of tlne Ltf nay be as hlsh as 40 Per cent
SaLrner (7) has sJrouqt that wherg ' than one wythe vrlth al interyenl46
, ' . ' : ' ' ' ' . : : .
' ' ' l '
: j : ' r ' : - " ' ' ' : : " ' ' : ' ' | . . . : . j : : . : . . . i
- 5 5
bonct, and gbod workrnah.shi.p. are' therefore :aXsd
favour-:mortar Jolnt'a nuch longer Berloit ls lequtred for watqr to _
penetraie ancl satrrrate ttre wa1,1- than foi conthuous natorl,al
if tne sane thlbhresb. In an 8-lnoh walL vrater penettatiou
usua1].y.occursfJrstat.thqhead'erbr.d'ckswherecont1riuous paths are prorrld.ed t}roueh the walL. .
praetloally .lmBetmeable brlcks andl nortar to provlde' a
-fusitlve uirrrfer to qaln. . Ratri rsping+1g gn.tFls prp9.o{,-we11
wlff nehd to zln off wlthout entertng the brlolimork bu!'!f ,^: ,
arly separatlon. cracks betrryeea -the br'Lolc and. mortar or d.efects in- wortuarrshLB are. prese1t water Inay rrrn throueF then almost Lrnnedl,ately due to tbe X"nabflity of t}e naterials on elther: slcle:of ttre erack to absorb water.
. , . . , . . . : : . r : . .
' bhe''trrorlananshlp Berfestion reguired-loT tnpg:nrlous walls of dense brlcks and norta? is dl.ffloul,t ,to obtaln oA ' the' Job.,because :of the neCeselty of ear:rytn6. orrt !Jr.e wo{< bs . s D e e d i t y a s . p o s s 1 b 1 e " ' t l 1 t h ' . n o r e p o r i o u s b : r i c k s n a 1 t h o r i 5 h
g6od woitsran3trlp ls requl,red,, snalf d,efects ane uot apt to be
sb seriousr . ,, : .
brtcksl (5 'to 25 grans lnttlal, rate of absorptton) provld,e the best cond.1tj.ons,:for conpLete and stropg briek nor.tar bonct, and. eodd workrnab.ship. |fhey are'there'fore :aXso fav abie:for a-high degree of-ra:
pnobable that such brtoksr ll reasonably lmpemeable well, thfougb tbetf absorptlve pro. Bepetration of water;. through
L i . r ' r i . i " : : . l . : : : . i . . i r : : . l i i ' ' i:r,:::r: r l i;', ','
fron the polnt of vlew.of durabllity to frost aotlon tf water Is traBpetl behinit an inperrrious face (f , 5 , 6l .
a moderate rate of absorptlon are used anil other oonstnrctLon and d.estgn factors are favoqrable'eoIld walls of practicalltr any type can be J-eak free.
(vit) Caviti waLls
In Brltaln the experler tlXfflouLt to obtaln a soll.d, wal Suttennrorth (45) states that al
Statdon a rqy large number of 1r raln penetration following an t rain" Some of these bulldlngs
It ls for thls reason that the Brltlsh Co€le of Standard Practloe CP 12},1OI (1951): Bdcta,corE states that only cavlty or slate:hung type ,watrls oarl bg rellect,upgn t9 Provide an absolute bariier-to. ialn. Thl3,.seems to be at varlance wtth the experience of Connor (tr8),. nut lt nay: only leftrect:the.,^ absence of the fatoUrable factors that he found neoessary;,'for raj.n resls:banee of ,so]ld br4e&.rval,ls or dlfferenoes ln
ex-poture. Connori dl"d flnd liowever:,that thlrty of thtr,ty-one unlts frftfr cavlty-watrls lvere,nOtstnre proofr'whlch was much the best record of any type of wa1l ,t .. , . . ,
'
noa"rdgg (a 1 ';*' 111"1,6o; ( 50 ) ' lnclgded cavltl ; walls anong thelr test Banetrs,and foUnd that excelleqt lesults we1.e obtatned lf :the:ce-weri adequate flashlnes 'alrcl dralna$e to
retrrrra to the outside any liat'erlthat,treiks'lnto'the ,eaYltx"'
[he' abooe-nen{ibned gr-i,tish Cod.e'of Standard Practlce elophastaes the oavitY, also, t!4b tJre
losg by'nortar droPPings ' ;he waII t1es. FlashingP and
dlvetrt,water to :*h- outslde ' L n g s ; , , ' , , ' , '
Horlzontal zurfaces should be weatherediand preferably flashed as welL, utj-th d.rLps to keep watel away from the wall
Gz). Gutters ibould be given proper attention ln. cleslgu autl kept 1n:.good repalr.
(1x) Pargpet wqtlg
,, Beoause of their seYere expoaqrer parapet walls requlre spe'olal attentlon. They should be-provlded wl,th aF lnpemeable .caB at the top and. completely cut off ,from the.walil by an
rmiermeatte fiashlug at ttre base (5, 6' 18,
42')-Cop5.ror (18) found that lt was a favouraU|g {ac!91 ,' towards a leakproof wall lf'the parapet uras provlded wlth a
I
3 5
-ctl:bi:off flashing at the base br lf lt was covered. by rnetal ' or felt'on the top and,baclr. It was Nelvrnants'(6) experlenee
of a parapet was covered :bJ l"lkeLy to be trappefl,,behtnd, ft
. llhts fre.qrtenttry promote'd,:: : en€ath the flashing':as a resuLt . : ' , ' ,'',Ar.deregg :(:$'r),:,reconunended, t h a t , s t n c e : p a r a p q t s b e g o n e '
satureteA'at tirnes that they be made hollow wtrth:weep,holes draLning ,tor :the roof,''just ab-ove the damp-proof co,urse at , l the base.
( x )
. '. Flt-ehed roofs,. u'rtth. eaves were 'conslderecl excell.ssf, : .
proteotion'ioi tlie top of brfck wa1ls bi''aneure6g (2), :';
Connor (LB) an.d. Buttera,orth, (45:) ;' l Buttewvorth' shrareed s,lso tiiaf,
tn rnany cases iatn ralls neaily,,r vertically:'and ,when ,the , Ouifafngs have adeqirate: eavesl thei,,mal1.:s doi not recelve mush ratn,' 4.r1dereg6, (,?),,,:Stat'ed: that pfui$ged, ;dlstrntogratectr. :or lnadequate eavesiroughs arrd ctovmspouts::' can often sattrrate I w&l-} so' tbat lealtage ,ooeurs. , , l
(xr 1 , qqgFdgel b,E!E #$;r.uioeqxr{I
;o j.nstalL an asphalt fabrte
bears.s .'ta' foi:n, a cut-off throqgfl-I levelg'; T}ts memn"l:ane ls ' , : ls thtBner at the beans
nd lt prevents water from eraeklig'ls llkely to' ooeur itk or novements of the
' ' : . . t ' i
r ' ': connor (l8):lrbuna howeve:nr' that suotr'waterprooflng actually prorooted: eraclcing because tt prevld,ed a cleavage plane where the nernbra[e turhed sut to '*he faee of, the wall" ..Rt ttre roof spanclrel, Barapet movements were found, to take
ipl,ace alon6 thls eleavage plane;,rvhereas i.n bulldtngs wlthout Ilttl,e evidence lvas seen of
. out of 76 bulldlngs lvere ierprooflng FTas not used. but adreLs welre watefBroofed;
t :spandrel beam watetproofln6 obtatrning leakproof walls (xft) Rrrrlng
-that all walls be firrqed wlth, ' ' dry olinates or In well ' ' d.ed that although there are
stereil: directt-y-on the'' lnslde
t:
leakage cavtty: ls
surfa'ce
gain ln mortar : and. i-s best
to 1t
3 6
-of the nasoru.y, furrlng ancl should be used e-\ren often brldged by nortar stated water unwise. vcas not
7. lll'TcH.rft
( 1 ) ( l i )ts :good th$rrrance agalrtst' f,or ,cavi.ty walXS stnoe the ancl debrls;
Strrllar vleurs ale also held bi'patmer (?, tr5) who
that header .bri.clq:'tn solld walie' 'sonetllnes.: transml't ough a waLl naklng plaste.rLhg' on the -brlbk.purfa-q coinor (].B ) found-tiat,; therhiwq-q','erridenoe , ,(tbough concluslve ) 1511 nr:rfng was ,iaes{iabIe,
: , l : : . . . ' i : . i : . :
'
" ,84r1y,.,,131 .'tr[6]}ife,,:'of':,trt:ok f 'lls
al-l..mortarg und'e,r8o'. dimenslonal bhangeq, usually shrLnkageri rchich, take plqce::tn trr,io stages {15,} .: i ghq,',f}rst, ooeurs whlle the mOrtar ehanges' from itd or161nbtr. plastio, state, tg a hardened oondLtton,dug_ ,to loss of wEter t6"ttre ,absorberrt ,br-taks and evaporattgnl _ If
lt takes place too rapldly the mortar nsy become too stlff
tb fowa tntlnate'sontEat'K;ith,'the brtck and shrirrkage ln
looalized spots may prorluce caplllaryiopenlngs through. whlch
w a t e r oalr Benet-:rate 12, 1, 511,9, 12r.59). f t r l s e f f e g t h a s :
previously been diseussed. ln
a f f e c t l u g b o n d , i . , . , l
(111) shrruFgge :Ffter 4s.{g-F$"r.}g
oonnectiou wtth: the faotors
(1v) Crack f,ormati.on and. reductlon ln raln fesistanoe due
, the ctlmensioual changos that take pilace durlng the
above two stages may be ilescrlbecl], as rrear]y shrlnkagel', 14
I as a resuLt of Lack of bond
rqpld sttffenlng of the mortar,
? l l n v e s t i g a t o r s ( 5 , 8 , ' 9 , ] - . 2 t '
- 3 7
1 r n p o s e d b r 1 c } c g r o r k ' . , o ' t h e w e i g h t o f t h e s u F e r J
" a;;;;;tieT=affiiir€xB@-no
sls_
Cfii.rt"ed-:.ti ,th;'hirnrbur. ,'bf ,s,eBaralion craeks as ,
ffiffi;-roii:ui*ilins;nd
n9n-load:bearing.
wallq. . {t ls
il;;i;-"- tfia t i tv'E'
lJrJi)i'J-LrIg V'q e v.rv .et3Y#qt q * . 1 g akap
.e
. 1", 19"Ii 131-
i31*t1..*:
-comparecl.
to horisontaI- Joini
;;t-G
Aue to
:$;;=iiltor-otilei--tnan"restralnt,
such as
work-uaqshiB. :
d.lfference was greAter fOr I llme morbars. tfhese rens east ln metal morllds"
erarly shrinkage than;Pure ceuen the 6frhion tfiat uortars contai hea}lng craoks ln the ioLnts bY t ' , , ' i1'.' i i . : ' t t : : t . : ; : [i., : l::: I t , t : : : l t : irr;::i :i: : '1 i.::::rit:ri:::::..:1'
5 8
-Grystals lq t{r,e'cracks. llho qgpe auttror as well as'Arrderegg $1 , Vosg (]5) ancl Wlss 635) aXSo c[;1r16ered that tree wealcEi llrue.mortars are Dore flexlble anet abl.e to adJust .to sna1l waI} movenents'and that when' the. straia exceededl the.llnit of
extene{on of ,the'nortaf the craeks tenct to be,small anil rnore cLosely spacect than with the -stronger and. more lrlgld, pure e e m e n t n o r t a r s . . . ' ' ' ' . . ' . '
-Salmer (g ) stateil that j ttre bond bet'tegn nortar, and na:sc to remala unbroken.lf the dLff,el thein I,s lrept to a,mtnfnun;. Ehls ls noted tha't he le,ter obserrred,
:denob,:,:ri'nr,'sup.par*,,;of. : thts {s
!ono:was:.ih'it1'al.:1J''eoEp1"*u..*ffiffi$'3,-''fiful.fftl.*e{,'ofiIil}"''...
d.q4age the'streng!]i.,.of.bond or inor6ase wall pe:meablllty.
' . . . i . . , , . : . .
(v) Effect :of noistirre movements . "
After,brlekw0rkl has been La1d up and. the mortar has f'the wbathqr,nray .subJeqt the tlng aad dryipg.- Wetiing ls ransion of the briobnork and
cts of molstrrre novemente on uQ{ed :: ptri,ncipall$,,bf $gderegg
L5).
',
A1l'lnvestigatS,ous have sfrowa thqt wheu nortar speoinens ar-e subjected to several cycles of wgtting,and dryine in--the laboratory, the groatest'obserrred, shrlnka6es ancl expansions take place.in the first one or two cycles. Ior stralsht osment morta:cs these first ferc ohanges in length urey 6o in
ent. Prrre llne nortaqs undergo changes, ' lTltlr 'both types of lng cyeles, reduce I"n nagpltude greater tend.ency to stabllize purg cement mortsrg. A1so, ln
appear :bo clepend on ttre:tfpe Palmer (9) morbars potuposeilrof
extrtblted velry little nols:. tar mtxes uslng dolonltj.c
arylng proponttons of Bortlancl esults between those obtalned
l : : i t t : : : : l : : : : . rlli 111: r.r :
1 9
-trs;irr6 mgrta:es contatutng,,,onl,y orlb of r
nateria:Ls' lri.t;h 'the ,na6nitud.e of the
lnoreaslng ir{ith the :cement oontent.
ths; tlto,, eeftentlng, ,,:::, , itimensi6n-al' chdnge s
., , PaLmer also fbund tha'b :
shrinkagesi ileie not ubually of .,,
Of ,; ngt',, A, : lfUrObe r,; 9f, :, qret| bips, ar.d
s, shsw th:at.,the, uragnltr:de ne. to' roclutiliie'novernents
aix. , In testsr'variatlons .!n
oonststenef ,as rneasured.' by the ff eets, but in gene'r;al1 the ,,; : ed. grea,teti :novenentg. ''
' , Pa1mer (9, 121 reported. the results of. testp made b:r wettl4g, ana ffiifig, bricks] ' wiih hard.-buirred. brleks we*ttng prcodl4ced:. negligible expenslon, but nrith soft-buuneB.blig$Et
even.,of,'the:sane nake, expanslons,uP to the order of O.O25 eer cdnt, :n6re r.ecdrd.ed.. Paliner rsthted that lt was' charaotel
per cegt, nere rec6rd.ed.
was,charaoter-Lsttc that, the specimens whlclr expancl,ed durlng a monthls
iulnerslqn tn. water d.ld
abLe extent when drled. subsequently shflnhone u,leek ln anr oven
aulr measur-about 15oo0. a to at not for
. Sfnce briehs'of good grade alre relatively stable aail
nortars are .sub ject ,to n6asufable dlmenslonaf' chengqs.r '1t '.
woul'd. aeem that tvetti4g and d-ryin$ of btickwork nigtrt prodrrce
differentibl mov-ements batr:{een the brloks'and tloortars thgt
xvpuld tencl. to break:the bond betrseen them. , This does not however :appear to ,bg th.€': cottcluslon reached frop investi'
6at1-ons. -Falmer ('9) stated that ttthere ls'l-lttle dlfferentlal
vol-ume ,ehauge if the nio:rbar con
This stateuent does not apply t
burned briolcs. tt 3alm-er and Pa ls no evldenco that vollrme chan
