Part 34 - cd3wd434.zip - Offline - Brickmaking in Developing Countries

Part 34 - cd3wd434.zip - Offline - Brickmaking in Developing Countries
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Brickmaking in Developincj~Count~i~> *' .
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-Building Research Establishient * . UNITED KINGDOM
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ai-Available',from:
I&ermediate Technology Pubkicatiqns:'
9 Ki'ngStreet
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Reproduced by permission.
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I’AKISTAti
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OTHltF??ASIAN
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PAKT E I’KI;RlTII3
FOR RkSE.AK(‘II
(kn’cral conclusions
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AMERI(‘AN
to clay winning and preparation
to brick moulclin~ methods
.
STATES
75
AND DE~ELOf~MENT
Illll3rovcnlents
to drying systks
Iml~rovcmcnts
ty rncthotls
of firing bricks
lml~rnvcnicnts
to Ilanrllin~syst~Il~~
f’riority projects
.
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58
61
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THfj.(‘ARIBBt:AN
C)Tf:jtK <‘l:N.f‘KAL
fiiiprov~knt~
fmprovcme~~ts
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and thcfe~,re
considcrBrickmri&ing In one form or another
l!as cxistccl.in a mlli&-ity 01‘ couhirics
able similarities
in,many tit’ thu methods
~mployccl.~Thc
main scope of this study includes some
~concentrated
descriptigns
pl;q~rocluction
methods
cmployecl
in twclvc samp)c countries
t:rom
areas of East, West, North and Southern
Africa. East and W>est Asia. Latin America
ancl the
featLires in sevctral othcrcountric5
outside
this
Caribb can, wiJh briefer ret‘crencc to particular
group.Qetsilccl
technical
matters such as clay unal’ysis or topographical
Icatb;rcj, of individual
relevant to,.an overall
loca k ions are ~iol.‘~ncoml~assccl
ilg this study ;IS thcsc arc jot gcncrally
f ”
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review of this kind.
.
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I
PART & ,INTRODUCTION
Background and apprhach D
’
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The approach
usccl t,o help iclcntil‘y prioriticsJo[
rcsc;Irch ancl’clcvcloprncn
t has hccn first to
assess working nieihods
ilncl cohclitions,
loolt; and c’cluipmcnt. ?cale ol‘opc‘r31jon and wnr~~;lace
of countries
with iommcnts
on pro’ductivityico~~suml~tio~i
I layouts in brick p~nts%-5%ririy
of
fuel
and
o%cr
rcsoLirces
rclatcd
t?
output..
and
Ihe
limitations
to quality of product
tlrrived’
: .
frori? choice of technology:
‘1‘0 relate 4hcsc clcsci-iptions
to’fuc;;I-ch
2nd clcvcloprrrtiilt
needs. ;I
summary section has been prcpurccl duscribin c circuin5tan’i;cu ib thi;‘diffcrcnt
c;ountri& in order
/
I- .to identify’tcchiiiual
ina[lc~lua~icswhich
o~~~~uvcr ;I significant
put of the ficlcl and which hold
.’ out promise qf being improvccl by Ltppropriate
rc.qcarch and rlc‘vclopmcnt
effort..
-
. i.,
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i
Experiehce
.
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I
i
The main source 01‘ inl‘orma(ion
incirrporatcd
i‘icldwork Llridcrt;lkcn
by the author,
ol‘tcn
*
in this qtudy is I‘rom I;r-cvious survey and practigal
in lllc course of conutruc’tiiig*or
iniprpvitig. brick
productioir
facilities in the clcvcloping
wo,l-Id. Most of the technical
&nsiclcrations
surrotiniling
Ftraditior;al. brickmaking
industries
have been found to have clircct rclevancc and similarity
to
circumstances
in hcuvily capflal-in tcnsivc hrickmakin g iii LYuropc and the Unitccl StatCs,‘3ncI
espcricncc
ha5 hcen Clrawii from both sectors in juclgiiq! i-cquircmcn.ts
for rcsearCal 2nd clcvelop0 mcnt.
.
.
Althoklgh primarily
a dcskwork,cscrcisc
reprocessing
illustrative
and factual inl.&m;ltion
already
to hand. all of the views csprcssccl
iI7 the u~l.limcntary
and the rccommendatio~is
for future work ’
are qbalificcl by direct and recent practical cxpcricncc
in most 01‘ the coiintrics
clcscribcd in the
survey. While the study conccntratcs
on th: indigenous brickmaking
tccjlnologics
cmploy~d
in
dcvelopir;g
coq trios. rcfcrcnce
whcrc appropriate
is made to the occasiona&hi$~ly
mecla~r$ed
factory-which
has hccn installed in,tl?cse countries.
The source ofi information
about these pkints
inclL!ding how they opcratc is utain mainly rlcrivccl from clircct cxlx%icncc and from published
inforrria.~ioii.
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The descriptions
of brickmaking
prc~ucsscs ~ncl some 01‘ Ihc prohlcms
associatccl witl? them are
mainly drawn from Bv”‘ork111the ficlcl .ancl ackliowlc[lFclncllts
arc COLIC
thcrcforc
to’thc local
.counterpart
organisations
with whom the atithor colla)orated
and to the overseas aid un~~clcvclol~p
ment hod& and‘privatc
cornpanics
through
whose aus$ccs
it was possible to visit the v;u-ioLis
countries:
__
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UK Ministry of Overseas Devclopmcnt
Y.
Koyal Netherlands
Govcmmcnt,
Ovcrscas Aid Ministry.
Economic
Commission
IIor Africa. Addis Ahab,
Ethiopia
f’ Unit& Nations Environment
Prograp~me, Nairobi. Kenya
:
The C’ommonwcalth
Sccrctarial,
London
United States Agency for Intcrn:ltional
Development
Government
01‘ Pakistan. Ministry of I~conomic Affair\
Govcrnmcnt
of Tan/,ania,
Small Industries
Dcvelopmcnt
Organisation
9
Basotho Entcrpriscs
Dcvclopmcnt
Corporation.
Lesotho
Building
Christian
Regional
Oxford
and R&cl
Aid/Sudan
Research
Council
Institute.
Ghana
of Churches
Dcvclopmcnt
Corporation,
Southern
Cqmmittcc
for Famine Relief
Sudan
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M‘inistiy of Finance and hdust+l
Dev$~~mcnt,
Ministry of Finance. Botswana
P
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Messrs Phil.lips Petroleum
Ink
‘0
P-E t’onsL!lting Group Ltd, UK
“!
Bercnschot
Moret BOS~~~JII, Nethcrkhils
EPEB. Burundi
*,
*
Drsarrolo
Juvcnil-(plnLlnit~,r’i~~
lloncl~~r~s
The’kambia
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The illustration
of hrickma!i?n~
in (‘l!in? on payc h(\ wasp
‘taken from 211 Arts Coumcil cx’lrihition Of#‘c‘il~~lllt .I’aint.@gs
.
.
‘.
from Sliansi Province. Chili-2..
e
tbunks arc also due to individuals
who contributed
written.o& illustrative
material or
~~pe&ce
and views whi& helped in the jjrepkation
of this study, to menjbers
of
l
‘,
_
Grateful
personal
ITDG’s Bf~ildin~ gnd Buiidinf Materials
Panel: Nicholas
Grccnacre,
Liveq6ol
School
T‘rol>icul f\lcdicins:-Dipi
l!~g Jtiles Jansscn. Ullivcrsity
of EindhoVcn:
Dr Robin Spencc.
correspondents
of th& Panel itlcl~ldin~Mc%,rs
of Cambii i igc; and to $ther associates%and
de Groot.
her
Bekker.
Ken Shehilt.
Desmoncl
Trigf
and M D Simpson.
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of
.
University
Caspar
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1 QART B. ECONOMI \&5S. OF a CHOICE i)F TECHNOLOGY
Range of brickmaking\technologies
availably-
.
-
.
A v~~ry wide choice of technology
is avaik~hle to any~one conteinplating
k~rick manufacture
although t;he higher the capital intensity,
the more restrictive
the !process is fqJKe type of
clays which ~a11 bc hai~dlccl. lligli technology
brickmaking
is also restrictive
in the foi-~ii the
cnqsb
rcquircd
can bc ~1x4. The very high mechanised
and :butomqted
plants rel>, on
clcctric power xncl,thc higher grad* of fossil fulls such as ;1atL$al gas 2nd propane while
trklilional
planls may Llsc scrub wood or cvcn c&ncl~cl~~ii g as their onlv soLircc.01‘ prbcess
cncrpy (olhcr.than
hu~&n .niusclc-kbwer).
,
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O.peratingrosts
Al the hi&cst’lcvcl
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of I%cllanisatioll
and aulonulien
which II+ hccn attained k the clay
‘*
,
hric!i-iniluslry
tlic input of labour is less thaii onc.niaii hour per thousand
bricks. aro\i~id‘
1
otie twentieth of a minule’s work per brick produced.
Al tkc In$lle~l Ievcl ofl,;fbour intensitj,
iri unmcchanised
tirick plants. tlic lahour~contcnt
may hc 35 Iijgh as IO mjriutcs work per
,
_ . ,,
.briqly;:
167 manhours
pc’r thousand
bricks. Il6wcvcr.
the rclativc cost of lubour also varies
uvcr almost as zrcat i range with some brickworks
labour in the United Stat,es carniny as
’ ”
mt~ch as f5 an hour while in parts 01‘ Africa t’hc hourly wugc may bc as low as 5 pence.
o
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’
4
However. in spits of the fact that the’ relative
heavy mcchan’isutioli.
;I considcrahlc
Iumbcr
have hecn estahlisliecl
in clcvclopin, 17countries.
skill4 labour. most of these plants encounter
bit’as high-as those in America or liuropc and
.
.
,
*
*
madc~ bricks is only
cannot Rc scrv’ctl by
-
traditionally-lnad~~
hric~ks; loaclhcaring
brickwork
in high-rise
huildinps
amI acid rcsistunt
ware. for csumplc.
Unl‘orlunatcly
Ihis type of application
is far less frqucnt
than the need
for brick fur ordinary
housing, schools and industrial
construction
and so many of the
mechunised
I‘actorics which have been unstructcd
have had to struggle to find markets and
.
frcqucntly
run at only ;I fraction ol‘dcsigncxl
capacity and usu;~1ly at ;I loss.
.
1
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inclu~trics. This is hardly
bricks :Irc’intfrchangcablc,
so t,hc fgrmer always win on price. The higher price ol~,mc~llanicnlly
justifiahlc
whcrc thcsc bricks c.;In I‘ullil special appliculions
;i;hich
.
I
Implications
of alternative
technologies
Capita! intensive
highly automated
brickmaking
has largely scttlccl clown into 3 familiar
series ok proccsscs
SO that anyone well acquainted
with the industry
is likely lo immediately
recognisc
th~b’saiuc‘ type of equipmcnl
in4tallfd in mcchanisctl
factories operating
in, say.
’ Australia.
Germany
or Algeria. Thcrc is ~111intcrcsting
corrclalion
hctwqcn
the level of
*
mrchanisation
and aulomatinn
2nd tlic scarcity rather than the cost”of labour. Once a
Pj
.
cal)ital-intensive
factory
has hc~~rl clccirlctl
up011 it is ;I colatin~lal
ihrcat‘ IQ the prosperity
1%‘ .’
‘?
costs of lahour and capital mitigate against
of capital-intcnsivc
automntcd
brick plants
With Lhc csception
of the unskilled and semirunnin g and financing
costs which arc every
so wo~~lcl also realistically
need to price their
products
at clo~~blc lhc prices of the traditional
unniecl!anis~d,
practical~lc’for
tkiges whcrc Iraclitional or mccliani~ally-prollLi~ctl
*
-
If wc iclatc the highest Ialhour rut& to the mbit autoniatccl
factory ;vc arrivk at a labour cost’
01‘ f5.00 a thousand
bricks ( I manlioul; s C5 ). On the other hand tllc~iiiosl I:ihoui-intensive
brick plant\ With rlic lowest uqil lahour ralcs rcsuli i4i ;I lahour cost‘ol‘ IO7 nianl1om-5 x,
.
5 lk~nc‘c a thc~usaiicl bricks: CS.35. only.slightly
higher thaii tlic i:lhur costs Of the ~iioslatitomatcd
planl and lhis CS.35 is tlicir only si~nil‘icaiit cosl and irlcludcs the’ work o<
gathcriny
I’ucl. II is thcrcl‘cu-c lkxsihlc
for qossly
laho<fr-iiitclisivc
brick factories in d~+clopi.ny cxunlricys to‘ 13~11bricks on the market at hctwccn
Cl 0 and C7S ;I thousand.
By c0ntras.t
tllc auloiiiatcd
factpry has ;I wIIoIc’ range 01‘ otlicr costs to csntcnrl. wiJh inclu~iiiiF’t‘~l~l.
pow~i-. \parc parts.. proc‘css ;~dditivc~ atid sGpplcmcnlary
Inatcrials 3s wclias tl;c cost of pro\id~iig the capital 2nd dcprcciatin, ~7the cquipmcnl.
As 2 result hy 1975, brick prices in the
de~clopcil
worlcl were mostly in c*cc‘ss of CSO a Ihokiancl.
more than double the pi-ice 01
lhc dcvclopiiig
countries’
Vricks
-that i5 lhosc midc in llic-very labour-intcnsivc
production
unit\.
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of the owners that
diffcrencchct%ct)
,
’
the plant may not produce
to jts &sign capa;i.ty.
T%c creutrst
illc opcr;lti’c;n ot‘ capital intc‘n\ivc and lalx~ur rntcnslvc plant
5ingle
financial
171
terms is @at jn the Tormcr, most of thz costs are fiscal >iicl ar;‘ incu-&l
whether or not any
bricks Are produced,
whercus in the latter nearly all the costs arc variable and OIICC bricks
also.’ ~lanafcniqits
\\ill increase t‘lic level of
sty being mqde the costs stop bein, 0 incuired
mechanisation
if they fjar production
holdups due to laboilr shortage.
.
/ diffcrcnccs:
t\
I
c
:
I
A;l,J~os
cclloril~ic.
,
td
hllrll
: 1 000
pc’r tonne
(hlc~:l;olllc\J-
‘\
‘4
Ilcat
. rlccd~cl
.I0 huni
- -WaigJit
01‘ I‘ilCl
.cquivalcnt
\;alue
.
4
’
I
(rollllr'\),"
OOQ
IYricL\
bricks
(>IJ,
p
0
.Moclctn oil-l‘irctl
tuijncl kiln I‘actoi-y
1
o off>.!
1
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)
Traditional
wood
f;irccl clamp
bl’ickworks
(Ixst Africa) -
Oil
I:ircwc$~l
i .
43 000
0.1 I
IO 000
I .OO
*
1 SOO’
C”OO0
000
\
c.300
I h 00
.s
.
r
Achieving the hi&cl- dcgrcc 01’ I'LIcI cl?icicnc!
rcquircs ali cxpcnditurc
01’ almost two m?llio,;
pouilds on t!ic kiln and its buildin y and 5,crvicch while vlrt\lall~ ii0 capital invc\tnicnt
is rc’quired I,r”the clamp. II‘ Ilie possibility
ciiic7-gc\ of obtaining
c;c~ntlnuous I‘irinc with ;I much
coal. thcii the cncrgy cast’
lower capital invcstnicnt
and with 2 niorc plcritil.ul I‘ossil I‘ucl
”
.
for intensive mcchanisation
is croclccl. As will lx scc’n in the subscqucnt
rcvIcM.of developing
world brick industries,
continuous
I‘iring is bcingachicved.
sometimes
in what art’ btherwisc
.
’ *
rather primitive
conditions.
Typical fklcl efficicnciq
achieved
arc as follows:
continuous
kiln
(Inclia/Pa’kistan$
‘1
?
Traditional
coal
lircd Bull’s Trench
E @t
Coal
77 000
0.20
,?
~
$
c20 000
5 300
u
Reasonable
fuel economy
is cvcn achicvcd
in manrl!, coal t‘ircscl clamp\
large enough and proaxr insulation
iiicasui-cs acllicrcd to: -
pr-ovitlcd
they
arc built
’
“I
Coal fired clamp
(Intli~ Turkey,
UK, ctc)
z
Coal
77 000
0.32
El 000
8 600
c
f
.,? The quantity
01‘ encry) ~OI~~LIIIIC~makes 111~Bull’\ l’rcucll continuou\
k?ln. (dcscriberl
in a
subscqucnt
section from page 50 onwards).
a very attructivc
proposition.
The snag with this
firing system as deviscc! at prcscnt is the necessity
to run the kiln with a fairly large volume
which may silit market dcmancls in the high population
densities
of the
I of throughput
Indian Tubcontincnt
but may bc too lnrgc for many. other dcvcloping
world locations.
The
most efficient
&amp installations
consume
ul~to 50 per cent more fuel than a continuous
.,
kiln hut have thexlvantagc
of being able to LISC a wjtlcr range
of f~~cls, including a numbct
of waste materials
such as clinkcy which may bc freely available- in the local arca.
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Labour productivity
The other crucial determinant
of a choice .of technology
is the hmount of labqur #needed to
operate it. Here again the difference
between
extreme
mechanisation
and extreme labour
intensity
is very large but so too is the range of efficiencies
&countered
in unmechanised
I
brickmaking
as can”be seen in the following
comparisons:
Manhours
Pi-oc&s frdm clay
pit up po and ’
including
formstion
of wet
clay bricks
.
required
.
to produce
.
1 OOOibricks
Process from
‘
‘comme.ncemenf
of
drying operation’
to
completion
bfafired
bricks ‘<
/‘
Total
,
0
Most highly :i~;tomatctl’
brick plant USA
0.4
Moderately
~nccl~ankcd
brick phn~, UK
3.5
Sandmould~tl
brick
production
scmtraditional..Siiclan
, :.
I
0.6
..
I .o
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* -32.0
Traditional
slop
brickmaking,
coal fired
clamp, Turkey
-
:
0
16.0
32.0
&
16.0
.
In the most cxtremc
instance of high LLlbour LISCdescribed
at the beginning
of this section,
a plant was using 18 men to product
less than I 000 briike in a day and accumulating
the
very high labour use of 1~67’man hours per 1 000 bricks. It can bc seen from tiie range of
results in the above table that thcsc more efficient
traditional
brick plants
three and five times the labpur’productivi?y’
of the worst known example.
indication
of the very wide scope that exists for improving.thc
technologies
.I’
in developing
countries.
0
.
Economics
of choice - operating
achieved between
This is a further
of brickmaking
.
”
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:
flexibility
A crucial factor influencing
the choice of technology.
to adop‘t. fo; a new factory
in a
developing
country
(or for that matter in any country)
is the likelihood
of a steady demand
for the products.
It is.the misfortune
of most conventional
brickmakers
that they operate
facilities which perform
best technically
and financially
when run,at a co&ant
output,
while their customers
in the construction
industrparc
more thari usually prey t+econorgic
cycles and varying interest rates. Every tine a surge in building activity takes place, the
L
6
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a
WliaY Ilappens next 15 an attempt
hy management
fdCed witli cash Ilob difficulties
to
rcdnomise
on operuting’costs.
The only significant
ones which are not fixed are tllose
associated.witli
prqdilc?ion
:iiid m3lntenanc‘e
labour, and maintenance
niateriaJ and cornponents.
Almost inevitably
si~c~lleconomic?r begin to al‘l’ect the plant‘s ability to sustain its
dcsigncd outptit.
Whcii 0~1tp~l l’alls. 1‘1x4 unit L”o\t\ begin to rise \b liicli in tilt’ case 01‘ the
Iieavy capita! plants u~~1:111yresult\ in ob~~rrlill unit cost\ going up in spite 01‘ the economies
in variahlc coslj.
Fic4
witll Iliglier lotal unit co’rt4. riiaiiagement
tlicn It,el\ ul~ligerl to try to recoiig pfirt 01‘
tllcse I.rom the niarhet hy raising prices. I lowrcer , ;I building recession is the wrong time to
raise pr?crs and Cti5tomen tend to turn to allernativc‘ materials
or rt’vert to Lising the products 01 tlic traditional
producer\.
l,t i5 alien sale\ 01‘ the ~iie~lia~tisrJ plant hegin to fall at
.tliis stagr’tllat
th< real Crisis begins. Stoc~ks get out ol’liand and managrnient
is forced to .reduce output by sliutting down one hi& il‘ two wel-e installecl or. il only one, running it
at hilf speed wliicli means~tllat nearly as niucli l‘~irl is still II+
but for a reduced quantity
.-r
01‘ hrick5.
_I
A Iieavy capital brick plant running ;jt 11all the [lr~l~ncrl-r)lltp~lt
I‘req&ntly
incurs total unit
Costs 70 to X0 per .seiit higher than when run at noril!al output.
I’ri\;ijrly operated
units
- genrrally
ClO’rc‘down al’ty- wbrking l‘or 2 time under these ~orirlition~. Whether or not public
money was involved
in llie original invt~5tmeiit. Slutc takg:ovcr- may l’ollow hiit wliatever
public corporation is involved; it rarely htands much’cha%ce of butting the factory back on
-its feet. ThrDs because during the runniplg down periQ$ essential staff will often have been
lost and.extensive~-damage
done ‘as a result of forced economies on &&tial
maintenance
”
r -~ i
:
and other services..
* c
%
.,i
;*
_
.
--.*
. ’
.
D
s The traditional plants during this time will‘$+Fuffered
an
but their react@n will ha44 been entirely~different,
which
’ most notable’feature
is common to the
the w.orld i;l:%t,o name juzt a few qam$es
1
d Mexico, Turkey,J$ypt
and,Lesotho. This fe’ature is that the
ex ect to keep gding.,at‘ the’same constan output. In fact&e
-,. P
&oun.tries mentioned op-crate on!y seas’onall.y,,anyway a.(d stop
i?.
season.
:
-5
:
yaving very litt[e”in the way of fixed
if they feel fairly sure there will be a waiting mar&t:
benefit o,f the b.uilding trade which in @my co~mtri
‘. shortage while waiting for the t’l’aditional producers
have stopped and itJs”sife to make bricks ag>in.‘sk ‘. *
,
.<
6s I
i
‘cy does not work tat&--.:.; :- e2.,’
th a period of severe brick? -, :
’
‘{, .‘
heir minds ihat the rams
,
_
_P
I:..
I
t.
.
*
D
._ ”
. _
The essence of.t$e resilien~ce of the traditibnal‘brickmakers
and their survival wh$n normal
commercial undertakings
would have gone to the wall,~can.be summarised as follows:
f
id
.
*
*,
Stockpiles of finished
,’ extra facilities.
is even possible to stop outflow of cash beforea clamp is fired, by’leating
bricks stih in the dry form, sheeted down foi protection against rain.
‘.
*
I
‘\\ : .
it with the
~.
._
.
Although the labour laid off from a traditional plant’*
suffer hardship during times
of low market demand’, they do not usually ,expect’or completely
depend on the
P,.
employment
and can .driFt into other work until things i&rove.
This is,certainly
I, I it
preferable to the brickmaking operation going out of business cgffipletely.
\\
: :
TA
-During a time of crisis and prolonged’market
stagnation, if‘alpelse f&the
traditioial
brickmaking
undertaking
can simply ‘disapbear and lie dormant. The only. indispen~
5
sible commodities
needing to be preserved intact are .the technical know&w and
,
-management
ability of the individuals concerned, which can be applied ‘fo bri% about
\
d
the reappearance”of brickmaking when conditjons again become favourable. .Meanwhile
. the mechanised plants being dependent on a complex combination
of resources being,.,
.
‘&‘ x’
.,
%p‘\
present to operate at all, will frequently have to be writte? off.
1 . :\,
Ql
‘~
I
_
” The mbs<commendable
feature of the traditional brickmaking industries therefore is that
‘i\.,%
they regenerate spontaneously:
Only in occasibnal instances have general market conditions
\ x.
or the arrival of mechanised brick production
eliminated the traditional operator. Where this- 1..
‘\,
,: .
has happened the culprit has usually been the sandcrete block which<& easier to makw-” .*
*,
quicker to build with and in the past was often cheaper, prior to the effect of the energy
1 .:
crisis on the price of ccmcnt. Since the time of the big rises in the cement price the&has
been a notable revival in some traditional brick industries and attempts to establish new
.
’
industries by many countries where br-ickmak*mg has died out. inthe past, or never existed
at all. *
a
l
*
.-
Ecol~omics of choice - quhlity and pricing
.
Offsetting
their advantages
of tleliibility
and survival ability.
the traditional
brick plants
.‘
hav; a bad reputation
for quality, which is perhaps understandable
for industries
which in
some cases have operated
for 50 years or more without
technical
controls or R and D input.
Variable quality rellects on price and in some~countt-ies.
the traditional
sector’s burnt clay
bricks at-e bought for as little as a half or’a third the price of a machine-moulded
concrete
brick. simply on the’grounds
that the ot]ler product
is more regulariin shape and more tireJictable
in prcformance.
In industrialised
countries
the position
is usually reversed with the
corntnon
concrete
brick valued much lower’than
clay facing bricks.
7
/
0
Accordingly,
the aspirations
of any organisations
investing
in a I~ghly mecha>ised
brick
e
plaht might in$le
present
cir;umstances
be
,that
a
regularly
shaped,
extruded-wirecut
burnt
_ ._1
clay brick would oL’ercome its cost.dis3dvantagrs
by c&manding
a far higher price than the
.’ _ .
S,.traditionally
made product.
Unlbrtunately
however,“maa)
p.lants have been bought oti’&e
* :. .
assumption
that with their enormously
superior productivi’ty
they should make bricks more
oheSply’than
the
traditional
suppliers
can.
This
will
only
be
the
case where basic tabour
‘,
.
* .costs arb tnore- than about CZ!.OO
per
working
da)i
ot25
pence
per
itour at current factor
a
’ &ts.
As: described
earlier typical wage. rates in the countries
considered
are very much
lo.&er ‘that; this: Where tahoui-costs
are tlwer than C2.00 a day. an itiveslmen t decision to
m
’ ‘opt for a hr~vill-mechanise;i
brick plant will only be valid‘if labour is scarce, or if the
*
m’:
apparent
quality of michine-&tdr
bricks puts ‘a i?rge premium
on their price. The second
justitK._iltioti of co&e
evaporates
if it can be shown that labour intensive plants can produce
.
the betfr;;lldality
bricks:demanded
by .the market. It is on’e ?f the cetltral purposes
of this
4
study-to
it!v>stigatr
the f&of> which lead to the poor quality of most of the Third World
0-r I)
traditional
briFk.rnakers’
products.
To ident$:y means to upgrade quality without
greatly
.alt.ering
the
bazc
nature
01‘
the
traditiofiat
p)aals.
could
significantly
benefit
both
brick. ,
.
,
D
maker and customer
in develb@ng
countrieSYU
-3;, .’
_.
b
J
I_ ‘C .’ - ._ .
.
c
Brickmaking
at tht?tnost’basic
level iS a straighMorward
technology,
not without
pitfalls
0.
ut
011%
wlyich
canSlie
reproduced
on-a
very
small~sc’ale.
To
find
the
answer
regai-ding
the
: ,;
“”
. ,:a
;
a~ppropt’i:Nr
level
01:
?$pital
technoldgy
to-incorporate
in
a
new
brick
project.
the
most
. \
’ practical approach
ie fi:sf to set LLP,,~&~Iall pilot plan’t, employing
three or foLtPn!en’t!laking
;,.*
..
‘.
,
2,
B .
‘&out SOd%ric*~%~. w&ing
day. This-is because the’quickest
and !cheapest’way
to determine
. ““=>
‘_’ .&hether 2 rllw matkrial is suitable t‘ol’~b;rickrhaking ma’y be simply .fo make a&rick with it,
L
.-.
raJ\$~ tljan inveSt in elabofate
a.t?d tiine co,t&ming
lab6ratot-y
testing programmes.
These
, :,
*wo@ ‘orj-ly :ne& io come later
of labour called for
* if maiket needs. or the. COSTor scar&y
0
_,
“,cT
,* ,L..’
with e\petlJiture
of a millipn pounds or so
proje’ct
.“>
a ~’ j. hea~‘lty-t~e.chanised”~;ickt‘aking
*
-.
I it would lie ynyise to’ przoi-eed wi&oLit dedai!,ed prior*exAmination
of clOay deposits.
However
PC ,:
“a,.
,
a.
Yor
most
projt?cts..
;I,
pil’bi
.plant
ai.tLtally“;Ua’kit~g
brick3
shoul<i:
su$ply
al’l
‘the
ncoessarq
,.Y
9 i
7. ,infomiat&
~n”2i.+tding a &ali$ic simulatioo
,of production
e’conomics.
* .
’
.+ .*
,,,
-0
0
CT:_,, .._s 2 J:, f 1”a’. ,, if- ,e :.
., :
:5.
5
J
i
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O.?
:
:.s!
-..- .
“-,“
o
-. ::‘>g$,, lfletho? and approach
$&t. ,_ in the descriptidh df brickmaking proc&,es in de&lopigg countries, frequent reference will
-*y,- @y-J .to b e made-to defects in raw materialsand
productiori processes which resultJn poor
finished brick: or outiight $ss. Rather’than attempt..to analyse the te&&~~~ackgr@-$
H
it will save time an4 mu&&e’&itibn
I ,” ,to each fault each t.ime it occurs in the commentary,
.? to devote a pAor section to the subject&f production defe’dts and ho? they occur.
.
,,’
’
:.
-.
‘.*,
I
b :
“‘,l#or a relatively simple object, a clay brick can &?o~por~&?a remarkable number 6f defects
‘.
in
d, hich in t’urn. detract from the product’s ability to carry out its functions in its en&
a, ,built will.
*
3,
~
c
Thb quality required’of a brick depends upon the use to which it will be put and is well
6
described in British’ Standard 392 1 : 19?4.
.”
n
-q
n
. ’
:
.
‘Iiterfnal bricks de&ibed.as
internal quali+ty’are suitable for internal use only and mayneed protection
on site during’winter’.
: y1 8 ._.
: k;
‘Ordinary b+ks,octidinary
quality arl less dvrable than special quality, hut normally
durable in-t%e external face of a building. Generally they do not n’eed protection on
:
\
site..when
stacked during one winter’.‘
.
.
‘.
. 4
‘Special bricks described as special quality are dura,ble even when used in situations of
extreme exposure where the structule may bccornc saturated and br Hozen for
example jn parapets and,r&aining walls’,.
I3
. ..
1
L
_.
.
Problems of frost on bri/ckwork only affect a few developing countries s’uch as those with
moun$nous’regions,
bpt-the extremes of wetaand dry season climates elsewhere tag equally
well disintegrate the fa+s of substandard bricks as can be observed for instance in’Ghana.and
f
’
the Sudan areas with nd‘frqst.
.
,
The Class that, a brick is categorised into relates to average compressivq strength. These .:( ”
range from Class 1 - ‘?.O N/mm’-, adequate for non load-bearing brickwork applications in
single storey buildings;to‘Class.
15 1 103.5 N/mm:, able to withstand maisive compressive
I
@ads, for instance in the footings of very tall masonry buildings. Not only the compressive
strength of a brick is important but also shear strength, a factor not always included in
*
‘standard specifications.
A brick of insufficient sh,ear strength to withstdnd some .degree of ’
loah will be suspect -asa tie betLween. th$ two ‘skins of a 2’25 mm brick wall’and will also _
create weakness in tl$ wall adjacent t.0 openings. BSS requirement&elate.to
{he UK but
in LD.Cs most building designsdo nc$ ass,ume avai!al$lity of strong bricks and compensate
accbrdingly. For eco&niy in appli$tion?
other factors are of importance, namely *regularity
in- size and; shape. Zt ,takes considp t ably-longer to lay mis-shapen bt$ks or bricks whose
dimensions are inconptent.
M?r ver, such products effectively increase the size of thRg+p
&
between tl@bricks +i$h invol$$s a significant increase iti cyst’ in ccjuntries where high
cement prices make. tfie price of &and&l mortar considerably greater than the equivalent
[ .
i/
tivolume of brick:
.:.%
The following catalogue of d&e&s is probably not fully comprehensive
buteshkuld cover
-’
the maili:recu&ng
faults which ;are .a problem, t-o the vadous brick indhstries .arid the{;
custoqers.
Some defects WI o&url,only Wit,h one type of production
process, such, as
extrusion.wirecutting
oi.siop molilding, othlrs can occur in shy type of brick+ Other
faults niay derive from inherent properties, physical or chemical, of the raw m$earials used.
Unless.theffects
of these prope&ies can be overcome by alterations’to
the process, theyW$ be disrkgarded as irreleyaqt to this commentary
as it’ is an entirely different’field
of
tivestigation
to devise how ‘to make reasonabb bticks otit of normally unsuitable mated&.
Foittinately brick earth of adequate properties is one of the world’imost
plentiful materials.
*
,2
c-- .:’
: * .c
,*
a
.~
l
0
,
-
,
i
-.
..:
:
B
.
The’ main classifi‘catio,ns of d
-strength, durability and-appearance.
shape, compressive
-
0
I
Defects of size I
d-?l rAs a rectangular prism, a brick has-three
result of faulty processing:
dimensid”s
,2
I
9
F
.a
strength,
_.
-shear
iI
c
\ .
v
.4
.!
e
“”
any one of which is liable to vary as -a ~~
..
A brick which is oversize in alI three dimensions
is usually. the result of a rp matee?
or ‘a firing
fault. With the, raw m,ate’rial the fault will prbbably lie in the proportion of coarse as op’posed to
fine particles in the soil. The presence of more.
sand and less clay will reduce the extent of drying and sometimes firing shrinkage of the brick.
In plants where b&ks incur. firing shrinkage as a
normal part”of the process, an oversize brick will
.usually ,indicate that it is undgrfired. This will be
confir.med if,the brick is also lighter thal) usual in
colour and ‘has a duller than normal ‘ring’ (4.he
sound made when two bricks are knocked together).
-I,.-,0
..=
-If the brick is oversize on1.y in width and length,
while the thickness is undersize, this will imply
thatthe brick has been inadvertently squashed .:
”
while still wet. This could occur in the sandmoulding process when the bricks are being set
(‘1
down on the drying rack or floor. It can also
occur in the slopd.moulding process if the brick
,’ drops out of the mould an$j$e operator presses
it to tlatten out the distortion thus caused to .the
shape. Extruded wirecut bricks will not usually
’ s!ffer this combination
of dimensional faults.
Oversize in thickness qnly. ThiiCrfault frequently
. occurs with ‘extruded wirecut b,iicks.,In the cutting process a long length of extnlded clay is
forced sideways through a row of wires. These
q are frequently set at incorrect.intervals
leading
to irregularities in the thi’ckness dimension. If
the other two gretnisize d$ensions
ar’e too
large, this should be a result .of?wear iu the extfision die and will be accompanied
by sbme
distortion of the r$%h&lar
cross:section..
,*e ’
:.
.
‘.’
’
.
.a
x.
Y -L_.
.
.
Those bricks whi?ch after firing turn out to be
‘* ,-- *, era11
.Y undersize in all diinensions can be
.’ *
It&
fesult
of several process f?$s, including
,
”
the” obvious mjstake of &ing undkrsize moulds’ ’
or extrusion dies i.n the first place, Most likely,
’ is inconsistent mixing of the material from the
quarry face with too high a clay content in tl$
.
,
batch concerned or the addition’of top mdch
I
water at the mi?jng=-s?tage, In either event the
und&sizin$ will show up by the’end of the
(
r
L
.
P
5
I
I
.I
_
!
-_
.;
-/
0.’
%
. _
&=
drying stage usually in conjunction with other faults.
Bricks,caj also become undersized during firing.
.y.‘. [
d’tie to over-burning. This’ frequently occurs *it!?
the bricks around the firing lunnel of a tiobb, fired clamp whic‘h should be sel$cted out &a
seoazate grade:
”
R
’
.
1
_
F
I
.
- -
-, .’
4..m ‘. .Q
I
>
.:
I
b
Defects of shape
T&e is a multitude of ways that a brick’s shape can become distorted during the produc-,
tion$5izzssand.,the
following description covers only
hat a regarded as the faults most
Y
tikely: to occur in developing countries’ brick plants.
~
;’2
-
“:.i
Slumping - ifzone stretcher face%f the brick&’
wider wirh a slight bulge running the lengt$,of
Jhe brick, this is. because,
..
:, ,.’
(a) the brick was $3o,softin’the
first plack,&d
so the % otfom spread as ‘a resulf of pressure
+
from the material above, or
Q *
.
(b) the person handling the brick.wQile
it down too roughly.
;‘a
r
weft,-&
1
Rounded co’mers - the usual cause of a
corner is a mistake by the Boulder who
.tp press enough clay into the’mould box
it.completely.
Brick corners are also lost
rough handlin&while-they,
are ‘in the dry
and, are particularly brittle.
missing
failed
tp fill
d’uring
state
B
”
‘1
i
.
B
c
s
Raised corners ,-. this is a’ o.mmon
moulded bricks caused b the corners of the
brick sticking‘in the m $ lld during the release
movement.
I
*
lip dn bet-face 1
caused bz the>.mo
clay cleanly~ ino;
the edge.
~~
noulding fau?
g off the cxccss
‘flasliing’ilrounc
4
,-
3
Flashing o”n sides of top face
this fault o?curs
with the use of fixed bottom moulds usually
in production
of frogged bricks. The spaces left
down the sides to allow air to enter the bottom
of the mould are sometimes wide enbugh for
cla’y to protrude. This de,fect has been eliminated
with the development
of the hinged-bbttom
mould but these are not yet in widespread use.
Distorted or contaminated
under-surface
one
4f the main causes of imperfections
to the brick
shape is the drying 00 r not being smooth or
covered with clean san!I . The irregularities of
the Hoor are transferred to the brick and any
loose lumps of clay or pebbles in the sand become atta&ed to the brick. These faults occur
mainly’ when the bricks are set down flat with
the slop moulding me#lod.
.,
I
*
l.
.
..
:4
Y
4
Stacking marks
hr-icks arc frcclucntly
transfcrrccl from drying singly lo dry ini in hacks in
order: to clear spa& for new pro%‘uction, and it
is a common fault for this to be done too sdon
while they are still plastic;, especially on the
undirneath
face. Whe~i this happens the ‘bricks
incur finger marks and also distortion due to
pressure of other bricks in the hack.
differential rates of drying
‘Banana shapes’
from one side to the other often distort the
brick shape to the extent that it actu~iycurves.
d This defect often rectifies itself automatically
”
when the drying spreads a&o& the brick, but
if the top ‘part of the brick becom@,fully
‘green hard befo<e the bottom has shrunk, the’
distorted shape remains. This problem can be
avoicled by gently turning over the bricks duririg the ini&t.l drying phase before the top sicle
~. has d’ried ‘cdmpletely hard.
*
Multiple di%mtions - some bricks inevitably
emerge f;or;l the production process twisted
and generally deformed. This may h&e
happened at the forming stage while the brick
was being shaken out of the mould and such
a brick should really have been rejected before
the firi;ig stage. Distortion can also o+.?ur with
the overburnt bricks at the base of the clamp d
or kiln.
m
i.
0
3
*
’
I
Defects of raw material body
Some ‘bricks although ~~11 enough shaped and accurately sized are still unsatisfactory
because of defects in the body which cause them’ to be too brittle, soft or unable to withstand
‘variations in temperature
or humidity,
1.
Underfiring - is one of- the Commonest reasons
’
for bricks be&g unable to stand up to-normal
;
use;andgan often be* identified when the brick
is ogersize (see page 10 above). Underfiring also
shows in the colour of the brick ‘which in normal
red-burning clay is lighter than the well burnt.
bricks. The traditional test is to knock two bricks
together; if the sound made is a dull ‘clunk’ instead of’s metallic r@g the brick is ~probably
unherfired and will have low ‘compressive
strength.
‘..
;.
9
. ‘,,.
\
\ \ IL.
v
.
Visible cracking - alGo usual!y indicates that
the brick&weak
and may even fall apart during ’
I
handling. Cracks can occur for a-variety of
reason ,.
7
(aj Straight cracks extencling at right-angles from
one of the long faces of the brick l?appen
I .
during the drying process if this has keen
;,4
too ra’pid. These will make the,brick liable
to break even when the-body i’s well COII$81
_ ylr--:1
solidated and fired.
c
J
(b) Multiple surface cracks running ih ral!dom .
directions are normally the result of hiffereritial drying shrinkag: caused by the
presence of lumps of diier material in the
clay which do not shrink as much as the
surrounding material. This fault arises from
insufficient &ixing of the clay before mould-*
ing or.extrusicLn_~PebblkS~in~-th~~y~i-~~--~
have a similar effect and all of these faults
will r&ult in bricks” with unsatisfactory
shear strength. 1
’
i
Large’ cracks associated wi,th 11bulge in the
surfaGe of the bricks are signS of ‘bldating’
aTault which occ rs when a ,l+n-ickis heated
up tod quickly du2%’ g firing and the surface
vitrifies before the chemical release of
’ _
cotibined water or various gases from i’nside the bricks. Although misshapen, such
bricks are often sq:md enough and.can be
* used for applications such as footings.
i
~
7
(c)
c
-.
0
.Ii
,
,
’ (d) Extrusion lamina&ons a,rc ddltcts whiGh’ _
occur only in solid extnided wirecut bricks..
q The problem is due to the turning effect of ’
the auger which propels the clay out of
Jhe barrel of the machine. The laminations
‘occur where clay in the centre of the brick
is being rotated faster than the clay’on the.
outside. Laminations are a’weakness’ and a
bminated brick is particularly susceptiblei
to frost damage or spalling ween corn:$
pressed. This problem &an usual iv.be over\,
come by inserting perforation,diks
into tlk
‘; auger’mouth which restricts tli&tu\ning
!
ovement
of
the
clay.
:“-4
YJ
I
j.
.
‘)
y
I
g
.
,
(e) Another kind of lamination crack can occur’
II with bricks made by the sandmoulding
process. This is caused when a piece of clay
. 0
with sand covering its surface is inadver-.
s ‘. tently mixed into the clay”of the beck.
‘The film of sand separates the clay on either
side of it so the brick will tend to split
at this point,if any stresses occur during
drying or firing. The’fault can also occur
with oil moulding. Avoiding laminations fro&
mould &lease substances is a -._
r@tter of
training.
-
.
5
. :.-
Defedts of appearancei %
When
bricJts
are
to
be
used
for
facing
applications
it is important that the colour and texture
0
of the surface should be fairly homogeneous
and
unmarked
by obvious flaws. It is-also a
i.
poor advertisemerit ‘for bricks of alleged g&d quality to have obvious surface defects on
*;the bed.‘face even thdugh this-will ndt normally be se*en in the beckwork. Several cdhmon’ 5 ;
: flaws &cur with both machine and handmade bricks::
.
\
:
:
‘Spalling’ - a fault to which extruded bricks are :.
especially susce’ptible but which can affect other
:
i
II bricks as well. This occurs during the early
v
phases of firing the kiln tihen drying is still
r
taking place. If the ,$ti.cks are warmed up too
quickly when residual absorbed water is still
in the clay body, this will turn to steam in*‘@
side the brick. and explode. blowing away part
of the surface, the process known as spalling.
‘i.
2’
‘D.og-ear&-arneq~re
a+x+mm+x- -km1
extruded bricks and are caused by poor 1
rication of the clay column as it emerges
the auger barrel. The defect occurs
even with
a well lubricated ‘column if the raw material
is too coarsely graded or badly mixed.
Ragged anises - on the long faces of extruded
bricks can also be a raw material defect b>ut
can also occur if the wifes used for cutting the
bricks i+nd
t’he side cutter are too thick or insufficiehtly tightened!.
Drag marks - occur on the bed faces of ex-’
trudea wirecut ,bricks when the cutting wires F,.
become clogged with twigs or leaves in *the clay.
They are unsightly and, w’hen a particula; large
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Similar drag marks ‘can occur with-sand-moulded
handmade bricks if the bo.w cutter used to strike
off the clay becomes similarly contariiinated.
Occurrence of drag marks on bricks is a sign that some
*
topsoil is being mixed’into the clay which is a
practice to be avoided, as humus and other
foreign materials can also affect the properties
of the clay.
4
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Another kind of drag mark OCCUQwith slop
moulded bricks when the moulder is removing
the excess clay with his wooden or metal
striker. This should be dipped in water before
use otherwise it will pull and tear the clay surface.‘
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Barmarks - on the face of bridks can occur during the firing process with many typbs of raw
material. If the preferred colour appiars on the
.
’ part of the face of the brick which iS exposed
to the kirn gases the remedy is to fla$ set the
bricks sb that all the stretcher faces Bre exposed.
- If on the other hand,. the colour desire8 odcurs
o&on
the covered surface of the bridk, they
_ should be set face.to face so that each brick
has at least one stretcher face fully covered by
another brick.
4
flat
^1
,
setting
‘face’setti-ng
Defects appearing after manufacture
The two most frequent defects which appear after manufacture
and sometimes even after
bricks have been delivered to site and have been constructed
into buildings; are efflorescence
on the surface of the brick
and he-blowing.
Efflorescence appears as a crystalline deposit
.
and is caused by soltible salts inherent in the clay or process water. The problem is usually a
temporary one and should disappear with time, however, it can worry builders avid cause
3 .
v
complaints. In iand which is inte;mittently
water-jogged, the salts will tend to rise to the
. .I ‘
surface@ the ground and,can be avoided by Wscardiiig TKtop layers including the topsoil
itself. Otherwise there is little that can be dqne to prevent efflorescence
except by adding
expensive chemicals such as barium“carbol;ate
to the clay. Lime-bl;wing is a more serious
matter-and is caused by qmestm- lumps in the clay re-hydrating and expanding hfter firing.
Batches of bricks can be checked for the presence of these lumps by ‘dunking’ in water
prior to despatch. If lumps of sufficient size are present t4ey will cause fractures in the
bricks and pieces of surface to spall off, leaving powdery dllite lumpgexposed.
To avoid
the lime lumps being in the clay in the first place, the: material should either be ground
or dry riddled and only particles under 2 mm,diameter
allowed\to -be incorporated
into the
process. Firing at very high temperatures
can Go eliminat& the expansive,effect
of the lime
which becomes ‘dead’ burned, but this procedure involves a’heavx fuel cost penalty and is
.
. not possible for many clamp applications:Higher
kiln temperatuqs
can also remove some of
the pote@ial for efflorescence
by turning soluble sulphates into more complex insoluble
.
salts or& driving.them off with other volatiles, but the brick i@ustryCdoes not readily
incur higher operating costs for the sake of achieving this type of marginal benefit.
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BRICK INDUSTRIES
1
PART’ D. TECHNICAL REVIEiidF
DEVELOPING’COUNTRIEi’
. .
Scope of informatiop.
The itiformation included in this section is not the result’ of any specially commissionpd
study tour of developing world brick industrieq,,but
more of a ‘windfall”nature,
using .experience which has-accrued as.a result of technical assistance work in the cocntries con-’
cemed, up td 1978. The coverage is not uniform, is seldom comprehensive
and in due course
will become out of date. However, the depth of experience is sufficient to id.entify common
themes and factors particularly
in an assessment of recurring technical pioblems, which
is the .p,uEpose of this’exe?Cise. The countries reviewed experience a fairly broad range of
climatic’conditions
and employ people from contrasting b,ackgrounds and widely different
racial and cultural groups.
2‘A
>The re&\?r covers, in’order, industries in developing countries
ainents of Africa, Asia, Latin AnGrica and .the : Caribbean.
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in v+ious pa!rts of the conI
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LESC)THO
*
_ Brickmaking is a technology which is very widespread in Lesotho parti.ally as zi result of tie ’
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influence of neighbouring South Africa where-brick is the basic building material. However, .
. _I
the technology employed in Lesotho differs from prevailing South African practice being
generally less capital ihtensive and prod&icing bricks of lower quality standards.
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The industry is made up of one or two semi-mechanical
plants
0 wirecut process with?: majority of traditional brickmaking
methods for forr$ng the bricks. All manufacturers
dry the bricks naturally with&it use of
heaters, fans or re-&culaied
gases from the firing proces? and they ,$l fire bricks in clamps.
.
The prin%ple fuel used is clinker - ashes from power station and +arn engine fireboxes
which can be igniteh when used as a layer
. which have ‘a residual carbonaceous proportion
between courses ‘of bricks in a clamp. The same material is also sdcled to the brick clay *
itself provi_ding a carbonaceouB ingredient to the clay body wh+h burns out of the brick
once a sufficient eytemal temperature, h& been reached. Coti1 dust is also qsed for this
’ /’
purpose. Initial combtistion is provided b’y burning coal or a mixture of coal and clinker.
I .
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in small hearths constructed’into
the sides of the clamps.
.
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With the exception of-two semi-mechanised
plants, thi Lesotho industry is a seasonal one
having no facility to protect drying bricks from the,rain. The biggest of the sem.i-mechanised
plants dries its extruded wirecut products under drying hacks while-a smaller adjacent
plaat
has low roofed sheds providing a small amount of coker.
II
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.- The ‘Lesotho slop brickmakers dry their bricks iii the open--and althodgh moulded bricks
withstand the stresses of rapid drying far better than do machine-extruded
&icks, heavy
losses occur due to frost damage, cracking in the wind and sun, &r when unseasonal rain
falls. The open air technology
also confines brick production
to t.he dry season which
. . creates considerable supply problems fof the building industry whose activity is less affeQed
by the seasons. This has probably be&n the main stimulus to the widespread introduction
of::. ce&znt bloc!kmaking.with its attendant greater use of imported materials and require,-, nient for transportation.
Introduction
of simple covered working and drying areas could
dvercoine all of these problems and brickmaking could continue all the year round.
i
With their very restricted outputs, the smallest bricbakers
calnot build-a clamp which will
bum :a reasonable proportion,of
adequately fired bricks. Bricks placed near. the outer suiface of a clamp are inevitably less we)1 burnt than those nearer-the centie. Thk smaller the
clamp th! hi&er the proportion of b$icks will be ,within’ a few inches of the outer surface..
Ideally a clamp should contain at least.40 000 bricks whereas sometimes the small brickmakers fire as few as 4 000 at a time with ‘c&‘s%q‘fiential higher ‘iYastag5 and propo@ons of
underfired bricks.
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SEMI-MEbIANISED
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BRICKMAKINGIN
LESOTHO
4
.
I)jcsel
powcrcd
douhlc-sllaflcd
rnixcr 1‘or clay prepration
Large
SC&
clamp fired with coal and clinker
waste from power
stations
.
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Problem$with
exist
both
slop
the
and
capitalextrusion
All
made
Lesotlio_are
in
there
_no
ex-vples
permanent
ln’simple
a
firinchmp
*of number
of
4
and
. .&!&d-d&&ricks
upoli
bed
fu.el.
staci
“5
&
and
1.5
4.5
-.
‘15.0
and
&&s-section
from
cf before
is-started,
&es
covered
mud
pre$de.
complefed
b vent
loss.
the’
ieadon
tCps’%re’
with
sheeting.
1
as
clamp
built::
*well
the
in
bed,
is
,spread
t e
sotirce
heat
referr&‘to”as
‘externally
dr
In
..
the
fuel,‘more
a,different
called the fuel additive, is m’iiced in wiih
‘@e brick Tlay. Approximately
50 per kept of tfie,heq-requirement
is supplie,d by e&h -, ,
source.
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Because of the different properties required the external and additive fu&must
be of
different qualities. To -ensure good, even burning th$ former must be of coarse, lump
. ’
* material, wliereas to keep ,the fired bricks as hdiogeneous
as ppssible, the additive fuel
‘_
must be, of small particle Size. The idehl additive fuel would have particle size,less than 3 mm
,“i diameter. As a result bf variable size and,quality of coal and clinker‘acided to the clay the
.
fuel’in-some batcl!es of, bricks burns out. almost complettly
leaving no ash r&due in the
bricks whereas that in other batches leaves a high ash residue in nodule Size equivalent to
that of the..original fuel.>These ash nodule inclusions cause lack of strength in the l$-ick and
are unsightly ivheh protruding t&rough’its surface. These protruding nodules may &deed
have a far more serious effect upon sales be’dause of their,resemblance
to hatiful
lime in- * . elusions whic_h absorb water, expand and fracture b?icks. Fuel consideratiors
do not have a’
e
’ beaiingjust on quality and the’ quesfion of wlG+ fuel should be bought fdr most economical
oper%ti& is’& important-consideration
for the b&&makers. Their tenddncy to use clinker
instead Df coal is frequently not justified in the light of relative calorificlvalues.
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‘-While thetscale and level of technology of thk small brick producers is regarded as to,o’sm&
the mdre.sophisticated;m&hanised
e$ruded-wirecut
plan@ may go too far in the oppbiite
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direction’especially
for areas without ready access to skilled gechanics
and ,‘appropriate
spare parts. The process of most concern however, ig in the drying systein employed in
is,
Lesotho’s sem%mechani,sed plants.. The system originally established w&s to stack up the
extruded bricks in drying ‘ha&s’ - raised stan.ds on which. to p,&ition, the bricks under a
miniature roof tiat provides protection against rain and direct sunshi$e. Tl& is standard
\
procedure and fundamentally
sound in rt!ost temperate and-,tropical/locations.
However,
/,,
certain ext’reme conditionB-occur
in the &,esot’hp climate with, pe&d$ of very low humidity.
’
The strong prevailing winds dry the stacksof
bricks so’rapidly andiunevenly
that large
D numbers crack. The remedy attempted by the brickmakers has been 10 firotect the stacks
-of bricks by cqvering them with-v-te+i.t-t+#-y
lifie&u&, when--l-ess-harsh--: .------’ natural drying conditions occur.
H:owever, the drying-time iequired fo$ a batch of bricks ’
now takes three to four weeks wI;‘en.it shou1.d really be less than a week (slop bricks dry in
three days). Excesgibly long d&ng cycles waste -oper$o*r time coverini the extra dist,ances
involved iri moving about; the large drying area and the upkeep of the sheets will be .a heavy
additional cost.
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Y
o
summarise,
the
Lesotho
brick
industry’s
traditional
prodqction
probesses and the main
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problem areas are as follows:
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Clay winning - Mainly a manual process using hoes and shorels.
of difficulty as the local raw rn&etial is
This is not a source!
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BRICKMAIUNGPROBLEMSIN&ESOTHO
in
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Stack of extruded
bricks sheeted wcr to prevent dryin? cracks and 31~0 :IS :I pJc,tcctio;l
This procedure
prolongs .the LJryinp period to 3 - 4 weeks
against
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Clay preparation
- This process is carried out using soaking pits in which the material
is init$lIy proportional
in layers, together with the additive fuel and
a then
. ‘turned over
and overZbefore leaving to soak. The procedure is a good one and further local,development
_
could turn the system into an effective clay preparation method. All that is needed is
to ensure that the clay is dug evenly and the soaking period extended by a few days to .
ensure all the clay lumps break down into an even plastic body.. WhatIs unsatisfactory
is the l&ge size of the clinker lumps put into the clay hhich’ leads to defects in strength
and appearance, (se,e Part C). The problem would be overcome by a system for crush- _j ,
“ing and screening the fuel lumps to reduce the particle size below say, 5”mm diameter.
t
Some brickmakers have a problem transporting.water
to the clay preparation pit particularjy by-the end of the dry season when the streams have stopped flowing. A-corn-’
bined well and storage tank, possibly charged by a wind-powered
pump would be a
._
addition to the facility.
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&g - The Lesotho brickmakers produce one.of the better shaped slop
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method consists
of the traditional industries in Africa. Their mouldin
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+of a two piece mould equipped with a bottom frog p&e. Each m’CL% er has two sets
‘~of moulds. After fdling the first sebit is carried to the d&g
floor and put down in the
0
.a drying position. The pallet is removed from under the.mould and, by ‘the-time the
.
moulder return-s with his second mould set, the bricks in-the first mould set are, suf*
I
,Xiciently loosened for this to be lifted off the bricks and taken for refilling. The moulds
,
ark painted in$de which greatly assists the mould-release action. The work of carrying
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the brick moulds to the drying floor is excessively laborious and possibly injurious to
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back muscles, however, and another carrying system is required.
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The distortion of initially Tll. formeid bricks takes place later during the drying period .
h
as is described in Part C. In their final dried form the Lesotho slop bricks are characteristically sunken in the middle of their long narrow dimension with a rough bed-face due
distortions would be overcome by
would enable the bricks to be moulded more stiffly
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Dryini - Neither the traditional industry nor the semi-mech$nised
brickmakers *have
overcome the problem that a wet season/dry season clima& causes for the brick drying
process. With the former, the rains simply stop brick production
while the latter have
_ only overcome the problem of excessive cracking during periods of low humidity:by
extending the drying period to an unacceptible
length with the useof plastic covering
sheets. The drying problems of *both industries‘would
be overcomeZby construction
of low cost drying sheds which would have the facility to permit or re$ict
the flow
for the varying levels of natural humidity.
1 of drying ai;-to accommodate
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Burning - The Lesotho brickmakers Y&e achi,eyed the best solution by,-opting for clamp.
firingof their bricks-and, in the case*of the semi-mechanised
plants, the clamps are
sufficiently large to achieve reasonable,efficiency.
However, no .brickmaker protjcts
the clamp sides sufficientiy from cooling wi.nds nor is the practice of insulating the
3 side walls with mud and rubble adequate to achieve reasonable insulation wainst heat
per 1 000 bricks exceeds 10 SDO.=MJ,significantly higher
” )oss. As a result fuel consumption
than the more”efficient
clamp-burning plants elsewhere. In operation the clamps
also experience problems in the initial stage of starting the fire. This activity requires p
use of an efficient hearth which maintains combustion without letting in too much
excess air which stows the temperatuie.rise.>At
present the hearth.arrangement
is .
-,-rudimentary,
using a removable grid’of fired ‘bricks which can hardly,produce
the best
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Inter,process
movement of materials - The use of wheeled trucks is fairly widesp.read
in Lesotho brick plants. In particular, the standard wheel-barraw has been universally
adij;pted:.However,
water is frequently carried rather than pip’ed or moved in a wheeled
truck.‘&d there has been little application of special purpose trucks and vehicles to
handle bricks.
P
To conclude, Lesotho”Traditiona1
Brick Industry is one of the better developed of the”
African indugtries. No -heavily capital-intensive
units have been constructed although one is
being contemplated
by the development
authorities. Labour productivity
is’fairly typical;
being’i.n..thePE.ange of 30 to 100 man ho& per thousand bricks. Major scope for increased
efficiency and better quality exists in the moulding process, brick drying and in movement
of water and materials. At a lower emphaSis there is room,for improvement in cl&p firing
and insulatirig methods but using techniques already known to brickmakers elsewhere.
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MALAb@ ‘I
The brick industry in Malawi has several similarities and some significant differences to that
of Lesotho; The climate in Malawi does not have such extremes of low humidity as the
mount&ous
areas o? Lesotho so brick-cracking’due
t*o over-rapid .dryjng is less of a problem.
To fire [+ie bricks, instead of using coal and clinker, Malawi brickmakers use firewood and so
clamp l&Gilding and burning follows a different.system.
An extrusion wirecut piant exists
i .’ .’
in Blai$pE but this does occasionally have difficulty in marketing its full production
J czipacity: ‘Bf, contrast the. traditional handmoulded
brickfields are active a_nd apparently
prosperq,gs, Firewood appears to be a readily available resource and as a rCsul’t clainps are
well stoked and bricks are relatively well burned.
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e
in this area-do the Malawi brickmakers
Moulding& again using the slop method and!@y
produ$ -rse
results ttian those in Lesotho and+then only slightly so. The brickmakers use
single ~&ilcJs and deposit bricks on the ground sftpight after filling the mould which fre~quently*re$ires
it to beishaken to release the cla$$with consequent danger of distorting
, the brick. However, mos$ Malawi slop bricks,aare sur&$irigly well
shaped far bricks of this
,..
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type.
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_,
An interest&g inr$vation.has
.been introduced
into the clay mixjng stage in this country’s
ind.ustv*. The slay workers use a-tool converted from~a standard hoe, which’can pound as
weil as cut:into the clay. This tool can be described as a ‘hammer hoe’ as it has a wooden
!
mallet head-oii’tlie opposite side to the hoe blade’and can be turned over with a quick
flick of,‘the hands. Knoyledge of this tool could benefit brickmakers in labdur intensive
piants in 0t.he.r countries.
a*,
!
ilbiicktiakers
produce frogged, solid brick; wl~jch though frequently well-fired are
variable.in’f&m
due to the slop moulding and drying process. Women frequently work in
the brickfields as jn Lesotho;but
the tendkncy is for them to work in groups whereas in’ ’
Les$tho.the moulding team often consists of,just two people-who work apart from ihe
.
,others.
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Drying takes place in thi open air - with the exception of the mechanised plant which has
enclosed’drying
sheds n$inly witfi concrete floors. The mechanised plant also employs,
wood fiEed kil?s, or m.ore accurately, a cross between an enclosed clamp and a scotch kiln.
. aThese kilns produce a more even burn than the clamps but at the expense of approximately
40 per cent more fuel”, konsnming 1% tonnes of fiiewood for each toline of ware. None of
1 the bricks burnt are Assisted by addition of any carbonaceous
material to the clay and rely
entirely on externally cornbusted fuel. This probably is a misled opportunity
as many
combustible waste materials Exist in the agricultural community
which could be added to
the clay tb reduce the firewood costs.
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BRICKMAKINGINMALAWI
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OPPORTUNITIES
FORTECHNICAL~M~R~VEMENTSTOTRADIT~ONALMALAWI
BRICKMAKING
n
*----> -7%
IL-‘--. ,o -The processes empl&ed by the trad$onal
induG~n%alawi
are summarised :
m _.
_g$*
_ .,” ~~
-~ .
-------d
’
, ~~ymniTig
and preparation - Using the. .h,ammer.hoe as the basic tool, the-quarry
.,,. --_ ----r;r?^ -workers both-dig the’(lay-in:the
pit and also mix it ready for brickmoulding.
Generally
the clay is moulded..dire‘cfl~ after mixing which should only be, possible with the
1”
easier clay mafe’rials and speaks well for the hammer hoe technique, -.
‘..
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‘.
,Brick forming and dr$ng - Malawi’s traditional slop moulders are ‘unusual in their
.‘4
adoption of a fixed bo?tom single mould, similar to the sand moulding tool. The air
gaps at the sides have to be. fairly large to release the brick .which produces a characteristic flJl?-g defect along the arrises (see page 12 ). The drying grounds are seldom well
enough prepared and transmit distortions to, the bricks whioh would otherwise .tum
-.
out as very well,shaped, due to the skill of the mdulders and the excellent moulding
properties of the clay. The latter helps to produce good drying results but the’lack
,
&
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of cover confines activity to the dry season..:
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--&ring -~The b&kmakers
around- Blantyre are skilled in building and burning ‘clamps
I
and appear ableto achieve higher temperatures
in the fire tunnels than many producers,,in
other countries. However, the clamps lackproper-damping
facilities to restrict the
excess inflow of cold air and.they also have insufficient
insulationand
protection
.
against cooling winds.
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Of the traditional brick industries reviewed, Malawi’s appears to be thf most sure of itself
and competent to produce adequate bricks with rudimentary
Facilities. However, fuel consumption is greater than necessary due to the open clamp fire-tunnels, and;se’asonal con1,
straints prevent brick manufacture
from becoming a steady employment
throughout. the
year.,
._._.___.._._~^
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_.+...------------- ~~~_..._........
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ZAMBL4
The Zambian brick industry falls pa-rt way between that of Lesotho and Ma1aw.i in so far
that both coal and wood are used as fuel, coal in the urban plants and wood in the rural
‘area. The urban plants incorporate the use of coal-fired k&s, initially down-draughts but
’
projects are in train to intrdduce continuous
firing. These plants even produce an extruded
wirecut“engineering’
brick with crushing strength above Class 4.. By contrast the rural
plants are known to produce generally soft tired bricks with only a proportion able to meet
the normal requireme,nt for common bricks. In a testing programme carried out in 197 1
s ‘me sample bricks from Fiwila and Chipeso in Central Province and Kasama in the
J orthern Province, had compressive strengths below about 3.5 N/mm2 although bricks of -.
twice this strength were found in Chipongwe, Katete and Nyimba.
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In other.aspects of qu%aIity, Zambian’rural bricks made by the slop process are generally
I
mis-shapen without sharp anises. This is due to the use of uneven moulds and poor moulding techniques together with lack of attention to the drying grounds which are often strewn
with lumps of earth and vegetable matter which distort the bottom face and sometimes the
whole bricR.as described earlier on page 12.
By contrast the problems with the urban bricks appears to be the high incidence of cracking which is a common fault with extruded wirecut bricks. The cause of this cracking was I
not fully identified although the likelihood was that this could be attrlbuted to raw material
preparation inadequacies and u-ncontrolled.drying.
To summa&e, Zambia’s brick industry
has the following problems
:
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The urban plants’ bi-ick, ;II‘Ctnacle,from alluvium which has accumulated
Clay winning
in the ‘dambo regions, small lopographicul depressions with relatively’deep
clay faces,’
up to (3 tn. These areas are usuj~lly flooded during the rain> which confines clay digging
to the dry season.. Handtools such as picks and shovels are used to dig the clay and load
it into tractor-drawn
trailers 10 move to the plants. The rural bricktnakers use hoes and
wheel-barrows but work t‘rom much shallower deposits and sometimes from anthills.
The urban plants’ extruded bricks are generally
Clay preparation and brick forming
produced directly out of clay arrivin g I‘rom the pit and without prior weathering which
cracking. Alluvium needs little
could point to one 01‘ the C:IIISCSof the cscessive
processing to t-educe particle size and Ihe main equipment ,used is the single and d,oou)le
shafted mixer prior lo exlrusion. Kltral plants use hoes and triacling for mixing the clay
anil leuve iL to weather overniiht.
IIcy
slop ti~o~~ld the bricks in double
cavity moulds.
Some producers act~12lly sand these tnou1~1~lo ;tssist Ihe release of the bticks but still
,
lay the bricks Ilat to dry as do the pttre slop moitlclen.
While the estt-uclcd wirccttt bricks art‘ generally dr-icd in roofed hacks similar
Drying
to the L.esolho pattern, the slop tnouldrtl hric.ks dry in tljc open on the ground. They
at-e less liable to crack than the extruded bricks mainly because’of a deliberate choice
of much sandier clay by the product’rh and 3150 because tlte brickmakers coverthem
with grass to slow the t-ate of dryin, 0 whcti nc‘ccss;tr\‘. ‘l‘his opc’n air procedure of course
conl’ities brickmaking lo the dry sc;t’roti.
.
Clamp5 ;trc cotlstt.tiCtcd to ~1~s sotnc~~n~es ;I\ large as 100 000 bricks. Most of
Firing
these ;tre cotistrtt~lc~l it{ Ihc opcxii 1~111
otic~,orks h;15 pc’rtnanetlt clamp walls and 3
metal rool whiclt prrmi1~ I‘iring cvcn during Lhe r;tins. Two 01‘ +e urban works have
pcrmanetit kilns quipped
with lctiipc’raIttre-r~cor~1ing cqttiptnent. The wood-lired
’
clamps hitilt I7y the ritr;tl hr‘icktii;tkcr5 ot‘ c‘ottrse have no ttistr;ttiletitation
and are
Ymallcr. abottI 20 000 brick+ anJ dtl‘l’cr III 5lritctttrc l’rom [he coal-fired clamps of the
L
Ltrhan ;ttuis. Large I’iritig Liititi~14 21-c‘huiti 5iniilar Ir, the Mal;twi p:tttcrti and the clay
is I‘irecl withollt c;trhoti;tceous contcatii. 134’c‘otilrast one 1,us;ika brick plant incorporates coal dust into the I,‘lich clay ;I> occur< with the e\trttdetl bricks of Lesotho.
-1.
While the urban brick proctttctinn process is evolving c.on\,en~ionall]i. along mechanised
lines, the rural bri+makers.are
unlikely ever to acc~~mulatc the capital for this type of
investment. The’ir clrvelopmenl
needs to conc‘cntrate around a be1 ter brickmoulding
system coupled with a low cost all-wruthcr dryin g system. Clamp biitning technology also
needs consiclcrahIc ith~jrovctiietit l‘or ht-ICES lo ac,hicvc tiiorc acccptablr
compressive
d
strengths.
TANZANIA
In the yoa’rs I‘ollowing inclrpi~titi~ti~c. l‘;ttl/ania’~ brtch tnll\txtry almost died out in may areas
OF the country. This seems to have INY~IIdue lo I;Ic~~ot‘ot‘Picial Support and in some instances the departure of Asian OWti~r-ti1anaFct.s ol’ lhe mechanised plants. A rural brick industry remaine? active in the south 01‘ the coilntrp, usu;llly in at-us where missionary
influence prevailed and some prison administt-ations maintained brick production
in
‘Morogoro and other centres l‘urther north. In rcc‘c’nt years brickmaking his-received considerable official encouragement
and village coopcrntives
and youth organisations have
set LIP production ventures while a government housing agency was given the difficult task
of Cvivi’ng the defunct mechanised plant5 in Arttsha. Docloma and liisat-awe nenl
Dar es Salaam. A large l‘ul-ly mechantt*rcl plant has been h&let-cd for Dodoma.
/
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BRICKMAKING
IN TANZANIA
Q
t
,
with waste oil, but this is the
result in this fuel being used for brie
those surr&mding Dodoma, the new
.
’
brickmaking is only’really practicable if some drying cover is provided. Accordingly, all of
.n --. ;these plants have cons>ructed corrugated iron roofed ‘bandas’, low sheds under which bricks
k ., ,
can normally.be safe from the spoiling effects of rain. This in turn makes it possible (though
:
not
easy) for brickmaking to continue throughout
the year. In periods of high humidity
. : ..___
,:
! l. _drying becomes very, difficult and production
inevitably slows down through lack of space
und-er the sheds.
’
due t’o inexperience:
-.
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:.
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in a position of relearning a technology
which had almbst been lost,
is understandably
full of examples .of spoilt bricks and wasted effort
l\
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selection of too refrac&ry,clays
which do not tire properly,
!
loose cattle walking through’therows
of drying bricks,
allowing ground water to run into
during heavy rain,
trying to burn bricks which are
starting to fire the clamp before sufficient.
od has been gathered
%.
,
burn.
‘1,
,
I
to sustain the
‘!;’
None of these can be considered long term problems which nee
development to overcome, as more experience should eliminate these mista
by the brickmaking
teams themselves. Assuming these problems are overcome preoccupatio’nsare
likely to turn
but-stillserious,
ape_rating defects
of
the
same
general
tylewhich’affect
! to’less%isasfrous,
-- - _
--- - .~~ --- \-‘\ -_ _~
brickmake&lsewhere
:
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Clay winning and preparatioi
-‘Tanzanian
brickmakers have to contend with afar
I
greater’variety
of clays than ,do their counterparts
in Lesotho, Malawi and Zambia. ‘j,_
I$oieover, many deposits have distin’ct variability between layers. To
a
@consistency
of mix, clay pits need to be,dug vertically with each cut%.
’
\\\
cross%ettion of the face. With standard handtools there is a tendency to
“\\,
hollow oFbottom
clay and-to allow the top measures to cave in
tches of-bricks with concentrations
-of top clay or bottom clay
LX,.,
\
“l.,< ‘1;
in them and con
ntly different drying and firing characteristics
and may cause the
‘-A
size problems referred to above on page, 10.
,
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Briqkmoulding
- Some of the early efforts at slop m,oulding in
brick plants have produced some very irregular bricks. The
mould which is very heavy to carry
have opte-2% q,use a four compartment
over on the ground and may’be much of the cause of the
approach was taken at one new production/training
@ant where the brie
a single,, self-releasing ‘mould in conjunction
with ,$e
better standard of hand-made brick is being made. The
pr6duc.ts are of.moderate
quality and vary with the experience of the
The ,main difficulty appears to be in keying the old
downs and spare-part delays often result ‘in the
for several days.
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BRICKMAKlNGINTANZANlA
-MOULDlNG'METHODS
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BRICKMAKINGINTANZANIA
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:SOMEUNSOLVEDPKOBLEMS
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Drying - The most common fault which may &I into a long term defect is the’tendency of operators to handle bricks tdo soon and to stask thein while one side isstill,
pT%t.ic. Some of the plants work to a system of turning the bricks before moving them
to stacks. This isth.e method advocated on’ page 12 to avoid distoriions at ihis stage 7’
in the process. The next most imp&ant
requirement
is $0 make best us6 of the intermittent good drying conditions whicli ogcbr.during the
plants at Kimara and elsewhere avoid pL@ting bricks
season. Use of a special handtruck at-one new plant
of ‘grec#’ hard, still damp, bricks out into the sun for fi
,underc.over again before qightfall or whenfrain is imminent. This can only be done
where running suifaces remain hard enough for the trucks: No system is yet in use to
accelerate the drying of still-soft bricks during humid conditions. This situation also
prevails in tl!e mechanised factories.
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Firing - Tahzanian brickmakers’ clamps are faiily crude affairs ‘and no standard
p4tter.n has einerged for corbelling the fire tul?nel arches or for the brick courses in the
clamp superstructure.
,Much underbilming
is currentljl’resulting
from inadequate
plastering and shieldin of the clamps and the familiar problem if cold air etiering the
tops of the fire tunnel
trances wastes much of the, fuel used: While firedood is
‘1
plentiful in some areaS, serious consideratioh
needs tb be given to using waste materials
such as chaff and husks to prpvide a L”arbonaceo&
content to the cl?y. No work .has
2
.
yet been donelo identify the appropriate
proportions, of these, by weight 0; volume,
42
*which should be added to the’clay.
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0” Much ofthe Comment on thz Tanzanian i;i‘dustry is Iyore concerned with t’l;e iemporazy
f’,.,
situation of inexperienced
operators Mfho will in time learn to overcomGmany
of their
basic problems. however, longer term problems over clay-~winninp~metliods’,idrying
and fi&g
.- (
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still need to be solvPd with better equip;,lhent and zyst~ems.
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Y NORTH AND SOUTH SUDAN
!
The brick industries of the Sudan follow a diffcrcnt technology depending on whether the
‘plant is situated in the north around Khartoum and Omdurman, or in the south by the
regionafcentres
of luba and Wau. N0rthe.m bricks afe small with stretcher face dimensions
generally under 20@ mm in lengthhnd SO mm in thickness and depend on the car*bonaceous
matter irr camel dung .for theit-conibustion
fuel: Traditionally
made southern bricks are large
with twice the stretcher face area and are composed of inert, sandy clay. The’Souihern
Sudan brickmakers but11 their bricks in woodfired clamps. Both traditional industrie’s slop ’ ,K* Fould their dricks in Gooden moulds but the n&them bricks arc fai more regular in form
.
, tkan those mad; in the SOLI~~I and are gcncrally harder fiicd. The north&n brickm’akcrs genGrally
.use double mo,ulds while in the south a single mould is the basic brickmaking tool.
I’ *
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Availability of large quslntities of cai7iel.dung is not a common feature of developing world
‘.
brick industries nor 1s the use of this material as a fuel nec!essarily the most worthwhile
.o
application. As will be pointed out in subsequent sections of this report qescribing gpplication’s in Asian countries, animal dung is a yaluable potent.ial fe-rfilizer and$ood’production
ethane *
should have priority use. Th6 ideal com6ination
is to process the dung to extract
which caA then become the fuel Source while le.aving the principal nutrients behi d irp the
sludge. However. no ready-made technology
is available to ext.ract methane.fro d’ qnimal
dung and bvrn it for brick?naking. Similarly, ho technology is’ available for recovering the
inflammable but usually.wasted
‘off-gases’ from charcoal prodUction. Thesi gases constitute
the major frapction of the fuel content of firewood and might well’he turned into a gaseous’
fuel .&r-an industrial piocess. Thi: proposition
i$ of po’te$ial significance in the Southern
Sudgn where deforestation
is a problem round populatiofi. centres due mainly to charcoal,
A ritionalisation
o$]he two
burning but made worse by the deman& of
of
tree
cuttidg
will
L
industries may be possibl&n some locations
. prod@
a grea+r total value of bricks and charcoal than if the two were burnt separately. j
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~ROJECTSTOESTAB/ISHALLYEARROUNDBRlCKPRODUCTION
INSOUTHERNSUDAN
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SOUTHERNSUDANBRICKMAKING-lNTRODUCTIONOFSAND~OULDlNGMETHOD
Sample fued bricks from sm;~ll brick antI tilt plant at Kit village. Slol~mot~ldctl
from clay slwvn iii inset on sight 01‘ picture
brick5 made prcvicwsl!
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The Southern Sudan’s brick industry is far-more typical bf African brickn?&cg-a&%ii;
traditidnal sector th,e familiar process of slopmoulding,,,open
air drying arid clamp firing is
followed, The area,has a long rainy season whikh has been known to shut: down traditional
;
brickmaking from Aprii t< Novemb,er. This produces a situation of alternating brick glut ahd
famine for the building trade’ for whom bricks, are often unobtainable
by the latter part of
the rainy season. The business of slop brickmarking in the Southern Sudan thfiefore
involves
a difficult cash flow pattern, as by April, labour and fuel costs will have to be expended’to
produce a large stock of biicks, many of which will not be sold and paid for until the
o following September.’
h
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Wgw brick.plaits
are being@ up alongthe
same @es as the-new plants’& Tanzania, again
as&ted by externals advice. These are based on the objective to continue production
into the
’ d
rainy season’ in spite of the inteeittent,
high humidity and penetrating win&blown rain
’
storms which affect the area. The pl?nts also incorporate
sgndmoulding with self-releasing“
\\\ moulds and a measure of mechanical handlin,g, using ma&ally
operated trucks. At this
istage however, the vast maj0rityg.f the bricks in the Jilba area of the Sudan are still pro:1
&Iced
by
tile
slop
brick
process
which
can
be
su/nmarised
9s
follows:
.
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‘.\.>Claywinning and preparhtion -~ These are performed at the sa’me time using hoes. and
tyeading with bare feet. The brickmakers normally choose the sandier clay deposits
..... ‘.‘.----....~~IKd-tol~~~~~epftfi~-marenal’s~~e~f
~~r~di~g~~-l~wer-ten~errcy
to-crackwiih rapid drying, (the new covered plants at Gumba,and Kit use more plastic clays in
t
.’
order,to produce stronger bricks).-One traditional brickmaker has however, recently
I
set
‘Rroduction near,the new Gumba plant. Water ~$~pply is a majo_r problem for the
‘
traditio~inl brickmakers when t$e water tahle,is lowest at the end pf-the dry seas’og.
The facility to raise and store water would greatly improve their situation at sites
distant from the River-,Nile.
,
k,
Brickmoulding
Little care and attention is given to{ the moulding process and bricks
are produced, in a variety of sizes with most of. the wqrst slop brick faults such as-raised
! corners, lips on the bed face and distorted bottom faces described earlier in the report
on page 1 I. By contrasf the trained moulders at the new sandmoulded brick plants are
producing adequately shaped bricks.
I
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Drying --lnitially,
dryiqg takes place with thi Slop bricks lying flat on the ground.
Cracking is sometimes a proble3n in spite of the sandy clay and is probablysthe
result of
harsh drying
and intermittent
strung sunshine of Southern Sudan. When this
occurs,.the moulders cover’the bricks with bundles of grass. As the bricks become
i
‘green’ hard, the b;ickmak&
build tli,e brick stacks‘tip into small conical stacks for
final drying.. No c?ver is available and so if unseasonal rain falls the brickmakers lose
the preVious day’4 moulding o&put. The bricKs inside the drying ‘cones’ survive which
may be the reasori for choosing this type of stacking arrangement.
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Fir,ing - As a contrast to their rough-and-ready
moulding techniques, the Southern
+’
S,udapese brickmakers coastruct
remarkably neat and compact clamps with a rectrlnplar- firirig platform and tapered top.’ Some clamp builders acfually construct a
permanent
surrdund for the footings u&ng bricklaying techniquek which simplifies
‘..thk work of positioning the tire tunnels’ for each new clamp. The clamp burners also
f6llow :a strict burning, routine, f$ing from .one side and then the other and closing
Bbth,e$?p
up once the toQ is hot enough t‘q’ignite straw. The difgculty of procuring
fuel fro?Cth&ii&ni.$ing
woodlands of the,surrounding
area causes them frequently
to run out before firing i53n-@et_e__and it is not uncommon to see a partially burnt
clamp of nearly unsaleable bricks.
.s--.-.._____
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SLOPMOtJLDED
BRiCK PRODUCTION
I
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IN NORTHERN
SUDAN
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The scheme which is nearest tdachieving
this goal was baked on an externally-assisted
pilot
brickmakipg project consiructed
in Kumasi, which led to the establishment of larger scale
plants in Asokwa, Ankaful ant Fumesua. The plants are constructed ‘and equipped from
Ghanaian resources and make bricks by sandmoulding.
Exper$nents
have al& been con- ’
ducted with a focally developed press which makes two brie-ks at a time. Initially the clay
was prepared by a small diesel powered single-shafted mixer, but this has now’been substituted Py foot tr?ading to save the present high cost of die’sel fuel. Initial drying takes
place on wooden racks under cover of the roof of fhe production
building and once hard’
enough to stack, the bricks.are take’n ,by manlially potiered trucks for drying outside in the
sun, as is the practice in Juba, Sudan and Mwambisi, Tanzania. Bricks are wo,od burned in
a specially designed’side-fired
kiln wit&dp_uble ckambers and a ce,rlZraI chimney.
.
_- --- -~
Ar+h&‘-series af1ti-&&ojects
has been based on imported mechpnised equipment
powered by a large diesel generator. These plants, at Sunyani and Ki i, produce an extruded
air,)dried., wood-fired brick,. Meanwhile, jhe original brickworks in ccra is undergoing a
m~jor-releq-~~ipping.d~~,e~t~pmb~nrs~ln
keeping the rather, comple i machinery running.
--Si_milar th the Tanzanian experience, Ghana’s brick ind.,ustries’ prdblems appear to be mainly
temporary ones awaiting the gradual dbvelopment of production
skills needed to establish
a brickmaking tradition to hand down’, as happens in other countlies. There are nevertheless ‘I’
.some basic technical draybacks which have not yet be& fully ov>rcome even by the most
successful of the plants:
.
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?
ing industry in atid arouncl Accra, K&masi and Bekwai
:
fter which production
ceased except torrthat of a
mechanised plant’on the outskirts oFAccra. This plant was equipped with grinding equipment, extruders, p$lletized dlying and a multi-@amber,
Hoffman continuous kiln. In the
post-jndependence
period the building industry was encouraged to use cement,from
the new
grinding plant ‘at Tema on the coast. However; the sub&titution of cement for burnt clay
added to the import bill; as the Tema plant carried.dilt only the last part of the production
process using materials shipped from overseas. As a result, from 1973 Qnward, strong official
encourageme’nt was given tq reintroduce b,rickmaking to the country ,which has resulted in
numerous different schcmcs
none
of which yet amount
to a’,‘traditional’ industry which is
automatically
being copied ancl~initiatkd by local entrepreneurs
‘or cooperative grdups.
t
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The major problem for the Sudanese briccmakers therefore is fuel. In the north, camel dung
.’ is no longer universally available and firewood to begin t$e burning is scarce and ex’pensive.
In the south the source o$! available firewood inoves fu’rther from the population centre with
.\ gptlmum
.
each successive year. The clamp burning process is far from reaching
results and
- the same reason as before can be quoted - the need to have a hearth qd%grate which maintain the fire w&l? preventing too ,much cold exce‘ss air.fromientering
t6’ .brick setting. For
“; 1 inevitabl’y slow
the covered ‘plants while prod;uction can take place,during. the rains, $t wi
y down as the dry”ihg period for the +-icks.lengthens
due to-high humid-ity. A~technology is
needed for,taking better advtinta’ge of the available periods df sunshine and better drying
afmosphere by, fbr instance, being able to move ‘quantities .of wet bricks outside and back
under cover fairly rapidly to suit conditions. If bricks are sdt into clamps still wet, a significant prbportion of the firewood is consumed finishing off the
should
___._~ which _-~
_~~ - - -~drying process
- ;-~- ~
havebeen~d~~fbmothing,
using the su<&%w‘ind~F~&e
dtivelopment for the Southern
Sudan may include a semi-mechanised
plant currently being planned by the hotising authori-,ties, and the sbread of brickmaking along the less-me,chanised ‘GuFba’ pattern to other
.’
\ centres in the region.
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BRICKPR~DUCT~ON
INGHANA
PREVIOUSLY
.
ESTABL~~HEDMEDIUM~~~LE:~LANT,ACCRA
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LOCALLYPRODUCEDEQUlPMENTOPERATlNGINGHANA
BRICKINDUS-TRY
*
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dlay winning L-Manual digging of deep clay faces at some rpral plants if unsupervised
will inevitably leah(to irregular l&tches of top and bottom%Jay and’variations in brick
A
size.
.
_
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Ciay preparation - While treading wi&l?afe flet can produccv&y
wkll mixed @lay ’ :
,r P&hes;-rht: ---probability is that the m
content would $a?&consiaerably
leading
-~
,.
applicat$ol;k need a propprtioning’system
to
! do furtl?er v?riati$ms in brick size.
d a Rcility to temQ,er the clay;over at leqst
mai&&-consist&cy
batch by batch24 hours to perrhit the
to hmogknise
tdoughout
the catch.
” ,,.; I ,,
: ,,.
b Brick f&m&g
.system is know; tb the (&an&an prq- :
.... .--~-- .J
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damp the bricks can take ten times as long’to dry. An appropriate
needed to. adjust the drying environment
of the pyoductidn-building
, ,/
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the extremes of drying conditions.
_I$ .i
tecl$‘ology is
so as i!b mitigate”
*,
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F&g 2 Although firkwood is fairly plkntiful in the central andOwested coastal areas,
it still amounts’ 10 a significant cost. kore eff$ient kiln grates or a larier propoytional
use of fuels added to the clay will be of great benefit toqhe economics of operation.
.
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. OTHEti. A$RICAN STATES
Many of the remaining countries in Africa have concentrated
on concrete products for the .
dev&pmkbt
ofetheir towns and cities, and others have developed traditional, brick industries
but with few features that are different from the examples give? in greater depth in the ’
previous parpgraphs. However, &me insight
to technic@ pro$le&
can 6e gained from a ’ +
brief r?yiew of industries which Gave been
by ‘the author or for which inf8rmition
,a .
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- is~av$ilable:
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In central Africa, BURUNDI has a strong-bricktiaking
tradition but withraliost
all of the
,’
production
grouped in a small low lying area near Lake Tanganyika on the out&irts bf
..
Bujumbura. Bricks are also,p;oduc.ed intermittently
in the hilly area of the ndrth’e@ of
the country., The nioulding and drying takes place in the open air which confines production
to the dry season. Mould+g quality is adequate and clamps are of a medidm size built along
r
similar lines to those of yaliwi. Shortage of firehood for the clarpps is a major prpockupation for the brickmakers. While there is-no indication that they waste this scarce
fuel-by firing wet bricks, there is nq evidence either that their firing tech.nique is any less’
wasteful than that of the other industries reviewed. Meanwhile in BOTSWANA the small
.
brickma,king+mits
use the same technology described in Lesotho with both slopmoulded
and extruded bricks, By contrast:; ETHIOPIA has little’traditibnal
beckmaking other than
the maki& pf sundried b&ks and this too is uncommon. Mechanisfd brick f$ohes
have ’
been donstructed in Add& Ababa using high t&hnology
processes lwith heavy electric !
gowered machinery and oil-fired tunnel kilns. The cost of run&g
the latter equipmeni is ’ .’
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SCOTCH
KILNS FOR USED FOkRRICK
FIRING IN AFRICA
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causing grave problems since the OPEexart-er
quadi?X$led the I&ice of oil and attern&
-a& being made tb overcome the financial drain of firing by trying, ,for instance to9us6
wood as a supplementary
fLiel,l’Firewood itself is a scarce resoyrce and any deldpment Y.
of a rural brickmaking tradition will depend on the availability of a m&h more efficient
system of clamp firing, burning less wood.and
possibly u%ng,vaiious agricultural waste
materials
as
contributory
fuels.
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-
Anpther country without a rural brickmaking tradition but with firm objectives to cornmence brick production
to save import costs is SWAZILAND. The projects have concentrated oii large-sc’ale schemegin urban areas. This country had previously obtained
all its bricks from South Africa and Mozambique both of,which have brick produ,ction well
established.The
Portuguese influence in MOZAMBIQUE h as resulted in the piedominance
of
1
hollow clay block productiori, these are%ot normally classified and therefoie come out of
the scope of this review.
_
..
SOUTH AFRICA has a very substantial brickmakjng industry in the developed, urban areas
cif that country and the full range of high technology equi”bn&t is in operation for digging
and preparing the clay, b,rickforming, drying and firing. In the last process there are many
tunnel kilns and several examples of-cgntinuous
Hoffnian type kilns in o.p&ation using coal
as.?he,combustion
source. The rural areas have many similarities to developin‘g countries
*
, in the same qpntinent and many exampIes of small scale, labour-intensive
brickmaking
’
exist. More interesting df.them are in the ~-4+as~-f~C.ape
Province arom
and.1
Worcester where the woodfired ‘clamps readpear togeth& with slopmoulded bricks, and
further.up fhe coa$ in the area to the north of Port Elizabeth, where small-scale brickmakers use brushwood
for fuel but undertake the firing in Scotch kilns tiich
have a.
reduced fuel consumption
- in spite of the extra burden of heating up the kiln structure by virtue of the p?sitiod of-firing grates directly beneath the biick packs. Brick production
in some of these rural plahts is undertaken by small extruders driven by diesel engines. The:*
extruded bricks are prone to the full range of faults described in Part C with cotimong
occurrence of auger laminations, ‘dbg eared’ comers and ragged arrises which preclude the
use Qf these bricks for any other than common inlill walls. .The lesson to be learned from
the quality problems bf the So$h African rutal brick industries is that mechanical equipment is diffic$t to keep in good running order without technically well-qualified attendants,
even when the plants concerned are within 30 miles of a majo.r industrial centre like Port
Elizabeth which haS the fyll range of engineering facilities.and skills available.
@
Q
----
.
*
The situation in KEN.YA, the second most industrialised state in Africa south of the
Equator, differs from that of South Africa. Brickmaking is absent from’mds’t kral areas and
only- ‘Mombasa and Nairobi appear to have a well established tradition of using. bricks.
Rural brickfields have played an important part in.building the small towns of Kenya in the
pa&and some of the best detailed instructions on the process have come from the former
co\onial brickfieldi inspector. However, firewodd for bum,ing cl&imps is now a much scarcer
commodity
than in earlier times especially because of the he&y demands of the chtircdal
industry and the emphasis in m.ost of Kenya has swung to production
of concrete and sandCrete blocks. The existing factor& are predaminahtly
tile works but make some bricks and
are equipped with Hoffman type kilns. They a,re no@ in the fact that they consume agricultural waste, rice husks, etc as a fuel, insertekthrough
feed holes in the crown of the kiln
in the same way that coal slac$ is fed in more coriventional units: This may provide a technical iead to furtherdevelopment
both in Kenya and’the embryo brick industry of THE
GAMBIA in West Africa? Here the decision has been to go for simpler labour-intensive
plants while most ‘oil-rich’ states of the African continent, ALGERIA, LIBYA and NIGERIA
have programmes for yeloping
brick industries b;lt thesk are ail on capital ‘and’energyintensiv-elines’using
very conventional
equipment as described .in Part B.
..
-
43%
,
-
COflENTIONAL
EGYPTIAbj BRICKM&NC
TECHNOLOGY
d,
.
1
I Icwy duty dicscl-pc,
machine used 10 mix
CLI)
crcd misinp
raw into the
Bricks mouIdc;i onto lhc pround
in atcnsivc
open working and
dryinC ;~rca xilaccnt to kiln
c
1
.
.
7
I
1
9
t
. .
On the West Coast of Africa,,there,ii cpnsiderable new inteiest in brickmaking projects in
countries which previously ,had,no brickmaking tcaditioti or, like-Ghana, where that’tradi..
tion had died out wiFh.the end-of the colonia! era:Projects
in SIERRA LEONE.and LJBERIA
d
are larker in s&e than the Traditional industries:tend
to be and are.incorporating
convvand layouts. Development
guthorities in CAMEROUN are inttoducing
.’
wood-fired clamp burning alo,ng fairly conventional
lines and in NIGER,
‘_.
t to buti ‘bricks- in a locally-d&ign.ed- kiln. An interesting aspect-of the
.
,
\
t is the-addition
of millet chaff tQ, the brick clay, a practice- which is
’
’
n with She indigenous brick industry in the Tera area neai the main-river.!
f
\
practice which has antepedents in the traditioial
&-it& afi?FI%Jherlands,
!)
adually build up drying ‘packs’ of moujded bricks by adding a fresh row
existing stack each day’.
1,
ks in Niger are regarded as a luxury arid most people have to be contentto
b&ld
b
do the’jirfhabftants of neighbouring’ MALf whe,re even in the capital, Bamako, mud.
‘jr
:
ion is tqe cqmmonest form of building masonry. The essential predominance
of
.i,p
.
<mud brick canstruction
~hrolghout
the Sahel countries is associated.with
the
Y
sence of indigenous fossil fuels. Such combustible
woods and grasses as exist are
needed for fertilizer and .for fumitufe and roofing and are t,oo precious to bum
,\,*a
The need for these areas is another system of stabilising or prot,ecting sundried
~~‘\
q
ch makes few, demands on the s$arce resou@s of combustible.iegetable
matter.
*’ i
- I,0
k
ti ,~\.;,
The 1ast’African i;idustry ‘visited’ before crossing into Asia, is inEGYPT. Here the traditional
4’
industv
actually does make bricks with’straw, one of the o%ly familiar examples of this
.~“h.
\<:?.
.i
k
e practice observed in the African continent, The stimulus for this piactice cymes, from the
general absencq of:firtiwooU and the high cost ;of other carbonaceous, materi&, Egypt is one .,?“’
.,t’
of the countries in which niechanised brick production
and’ traditional handmade brick\’
,making coexist. The dramatic rise-in the cost bf refined fuels has naturally damaged the
,:
’ econobics
of mechanised production far m&e ,than that of the traditional manufacturers
who bl& their kilns with crude oil. Competitiail
for agricult\iral soil since the Aswan High Vi
Dam cut, off the renewable s~~pply of silt makes the river bank brick industry vulnerable to.,:’
criticiim. New sources of clay have been discovZred on the epst bank under a limestone shd.fayd these sho~~lcl now be exploited. In the lo&r
term the blest interest o/Xhe b&ilding in:‘
dustry is to turn again to partially building in mud with new\$chniques
to improve dur-;l-?
c
:
ability. :
i
_. -~
.
‘P
I.
The positiofi of brickn&kin$over
the .African continent IS full of contrasting circumstanies
‘which call for very different solutions. The predomin&t
pioblem appears to be how {o
dbtain the desired duration and level bf temperature
for burning with the minimum cov,
sumption of fuel. Second only to this comes the pr blem oi”maintaining production levels
in spite of sometimes extreme variations In the rate t which the bricks will dry. Raw’
materials generally need to be dug and niixedmore feve 11y than at present and the propor-.
tions of water added better controlled. The handling of materi& and- dried or fired bricks-’
between processes is, frequently one ofi the most labour-wasting
parts of~the traditional
technologies
and much of the work is unnecessarily
uncongenial
due to. lack of suitable
\
tools and equipment.
“’
. .
*
*
ea
,*
dJRKEY
”
E,xamples known’of Turk& brickm,aking cover an equival.ent range of capital intensity to
two African industries, those of Ghana and South Africa. A fadtory at Pamukyazi in’ Torbali
e.
District operates a continuous,Hoffman
kiln of the type used in Accra and in t‘he Cape.
-D
This kiln is coal fired, fed
through pqrts in the chamber crown. The plant
,
as a whole is equipped
areas in which the products take a surprisingly
-lobg.period to dry - 20 to 45 day
the products, the plarlt employsextrusion
.:’
‘1
----._____
. -... __
_._
TRADITIONAL BRICKM+KING
.
/
IN TURKEY
.
I
n
-*
,
t
:
-
\?
?
I
\ ‘3
I\
?
J
,
eqi@ment which is u$d to make floor blpcks and hollow
is left to tht traditional industty.
bricks: Production
of.
-
*
;-chaqer
barrel-arch kiln seems unusu?lly short (thi generally accepted ‘minimum’
s&$ being 16 chambers) and duiing the hottest part of tlie year’it must be a maj-or pi?%lem
the draught and moving the fire to achieve a heat transfer, because the chanibers
would be ~l~rnostto%7iX~~~ men to enter.
’
*’,
Enterprises bf the Pamukyazi type will have taken a major capital inve
to set up
whereas not far away in Saglik -Kayii; brickmaking is carried on with veryi small resources
$f equipment which will have cost very little. Six or seven brickfields operate in a small
0
brea us&g basic equipment,
most interesting among which is a h$rse-po,weFeg’ pug mill
if-or mixing alluvial clay with water. One such unit is apparently able to keiep three groups
jof five men sypplied with moulding clay for 10 000 bricks in a day. ‘The &@Vaches #the
imoulders’ table by wheelbarrow having been’ first sh’ovelled out of the piJ l$elow the
r
0
jpug mill. Moulding combines #he technology of the slopmoulding
flat
.*
*im&lding as the release method. Bricks are carried to the drying floor
.deposited frorh the mould onto a.sn$ooth level ground.
+,
1,
.
,..t,..’
2 I
*
It:
,’
In spite of this fairly well eqiiiped
production
set-up, the
ducg a full range of moul’dhg faults with missing
, botfom faces, and setting marks. Wifh what is
+ndustG should be capable of $aking a first class handgnade’brick
;
. y!
,,: to their working methods.
,
.
with son14 modifica.tions
/ c
“C
I
‘Their clamp firing is clearly a fkr more well regulated process than the brick(noulding and
the brickfields contain large a{curately con&ucted
clamps which showld achieve a good
mep’rmre of consistent burning: at adequatp levels -df fuel effic@cy.
This is obviously
neiessary with Hoffman$ln
fired units competing in the s/he trade:.- ..
,’
1
i‘ ”(
..
The main fe& for the tra
brickmakers wili be unsea onal rainfall, as tens of thousands
of bricks on the’drying giougd could be written off in a fiw ho& il: this occurs.
;
Lm
.” -
j
.
‘b
1
--I
Y--K PAKISTAN
Tlvo types’of techbology
operate side by side in Pakistin with at-least two mechanied
plants already established in urban areas and a substantial ‘traditional’ industry of small
enterprises, working with simple tools and equipment on the outer fringes of large towns.
An important feature of this country’s industry is the facility ofsope
small brickmakers to
produce a first class handmade brick in spite -of tlieir lack of sophisticated
production
,,
equipment.
\
L.
.,
f’
”
Clay wiying and brick moulding - These bettkr bhcks are frequently,‘made
by very
.I skilful moulding teams often working ip the most c;lifficylt conditigns in th$full heat
” of t!le, sun, manially mixing their own’clay;in’shallow
pits alid setting the Ibricks out
the ground. The moulding technology is substantially
Similar to!that of the
described earlier but the’cbnstraints
of what t@e market will accept
be different, which could account for the existence of spe higli
the slop,,poulding system is employed and many of these
stanflard which. prevails over most developin
countries’
traditional brick indust+..
,
‘-
r
‘*
. .
‘\
:
’
f
I
’ Brickmaking by many of Pakistan’s traditional producers is an itinerant process as it
is custErnary, only to dig shallow cla.ypits so that the land can be conv’erted back to
I agric Itural use after brickmaking moves away. This feature discourages the establishing o1 cOvered work areas which in turn keeps the nature’of employment
intermittent
I
and Incongenial.
\
,
*
1
..
Dr)iing and firing’ - Lack of cover confines tradition$
bri&naking
to the dry seasor;
for the.reasons described in earlier sectioris. Heavy rain also affects the early production
,
gages and ihe firing process. ’
a
B
I
second and probably most significant feature of Pakistan’s brick iridustryis the,
espread use of a contimhs
kiln by the traditional industry. The unit used is the -. :.
‘s Trench,,an open topped versiqn of the barrel arch Hoffman kiln which achieves
“d : bfficient re-use of kiln heat by drawing the exhaust combustion gases from bricks being
to successive:)b$ches,of
bricks awaiting burning. The efficiendy is eninput cold air is progressively h’eated”up before it reaches
passed throu& the bricks which were fired earlier in the Cycle and
hich are now cooling down. T&s contin,uous process is made possible by.gradually
o\ring the fire round an oval circuit from which the burnt bricks are.withdrawn
after
by leaving a space which is,,filled with new batches of dry bricks
is achieved by antall chininey positioned ahead of tile fire
from~the eptry point through the fir,e and forward through
j the bricks w%iCzhafe thereby preheated to dull red before any fuel is actu@y fed into
the charnbe,;:,
”k
,
*
.
,
m
\
movhble chimney is commonly regarded as aisource of difficulty and high main“lenance
co;t due to handling problems on windy dati and5 the corrosive effect dn the’
,.,
steel tube of the-products
of coinb$tion
frpm coal firing. Some producers in the
Rawalpindi-lslamabad
area have in&ted
in permanent brick chimneys, positioned
.’ ‘in the centre ‘island,’ of the kiln. The gases are brought t6 the base of this chimney by a
central flue which is controlled by a System of dimpers. Fuel efficiency is far higher
than that of intermittent
k’ilns and clamps but pbducers
often use insuftic’ient coal to
burn the bricks fully, with magimum temperatutis
o’ften not exceeding 900’G.c
,
\
.
I
_.“v
:
of natural ‘&ii’ gas which is
these kilns are necessarily top
gas firing as this fuel is use@ at
_’
setting.
.
@
4
’
One of the main. technic41 problems of the Pakistan briqk industry is‘efflorescence,
due
-. to
+--?I
, herivy inpregnation of sul#ate$ in the s&l in turn caused by water-logging of the grourd.
The traditional bricks are.highly porous and in burning they rarely reach a temperature
necessary to neutralise the effects of magnesium sulphate and so as a result efflorescence
frequently occurs and can occasionally
be severe enough to affect tKe propertiCs of the
brickwork mortar and disrupt plaster coatings. The solution to this.may be a local one and
involve changing the practice of digging shallow clay pits in fav,our of,deeper quarrying
%4 which would effectively diminish tht proportion
of salts in any-given bitch of brie? clay.
,-
Pakistan is’fortunate to have discovered large quantities
now being used to fire bricks in Bull’s Trench.k,fi&. As
fired~units,)hey
do not always achieve best r&tilts .tiith
it,s best thr&gh side, firing burners near the b’ase%f Rhe
.
’
.
In remoter aieas away from d’onvenient sypplies of co& of ‘Sui’ gas, brickmaking,has
to r$ly
*’ ,I
on other fuels. It would be possible to bum bricks with s&b wood iii some of the forested
’ 1
mountainous
areas of the north but this is not apparently done at present. Similarljr, the
,_
-A---commonest,domestic
‘fuel’ used foi household cooking is cow dung which could pre___zA~3
sumably be used is a combustible4dditive
to brick clay as is done with car&l +mg-in%~’
Sud’an. How&er, fhe case is so strong for this materiaf.not to be bu_@a-t-ail%& to be used
instead ab’fertilizer, t&t this proposition
should not be -aconsi&&&
If it were possible to
II
Exhaust gases still
hot enough to
eate draught
w
I.
-Red hqt, alea’of
fuel IS Inserted
.,
Bricks awaiting arrival of fire
@ warmed by kiln structure
kiln where,
I
Fired bricks being taken
away
,_a. _ _
7
,
.
Ash and rubblron
“top maintains
draught seal
Bricks in chamber
cooling doyen
J
Air warming up as it passes
py hot bricks
.
collect du& for d$ntral’psocessing
fo; methane product/on
and to burn the methane in a
brick kiln, then ~hC&~p~ition
mightmakcmore
sense, as~thef&tilize~~u.ld&il~a-in
-- ~--- m-1-- -~Iin”lfrs;,sludge. Sonfaf no.suitable’technology
for combinitig th;s$-activities has been developed.
_ --- - ~_.
,
~. *.;$.L.-, :
i ,:
-;---*;.2 , ~JI
‘,
., ‘.
,
‘,s>;.‘T _,
.I
I
INDIA
;
,
Much of India’s irick industry generally fits the description of the process as carried out i
..;
,
Pakistan. The ,&il’s Trench kiln is in very widespread use’Balth?ugh there appeals to be, t
:
many more examples of clamp burning in India arid also som’e instances of woo3 fired ’
.
intermitt,gnt kilfis. Much less of the’
is hbre occupied by the need for
therefore tends to be concentrated
: metl$ds are normally used to,dig t
’ trda&ng to grepare the raw m terial fo
parch clay for several days’ we“bth,erin
content is allowed to evaporafelawa
7 moulding. Th% is a fundamentalLy So
,
, makers in many other countries.
.
In some brickfields the same type of
appears also in India but instead of be
controlled by an attendant. Indian brickmakers in manyYar2a
variable climate ,than that of Tutkey or Pakistan and as a resu
enqp$tqr
a proper working building constructed
alongside the
.mouldedi and set out t(, dry. T.hiGs facilitated by the availability
roofing material, the Mangalore tile.
.
,
.
India has many examples of mechanised brick production
using tl
process but the piice of these bricks necessitated by the cost of ow
machiqery is generally more than twice that of a handmide
brick
instgnces of calcium silicaie b$kmaking,
inclL!ding one unit in K
pressure autoclaves to steam cure bricks made fro.? s8nd and lime.
is more than-&ice that of a handmade brick - the tomplete
reversa
Britain where a handmade brick fete
haqdbade
bricks from mahy other developing countiies, the mo
brickFakers
can be extremely pr
to copcem the firing rather than
,I
Generally the Cduntry’is well equipped t’? evolve its own technol
making, having central trade and research organisations in New‘b
having the necessary industrial bas
much of traditional b.rickmaking is still laborious and unple$san
manual operation and. interprocess handling. Therefore any ne
designed to lessen the laboriousnes’s of moul&ng bricks and
processes of makink, *drying and firing will be of considerable
4
w
_
t - ..
n
rmal to use two bullocks
to contend with a more
far more common to
4
,
xtruded wirecut
and operating the
g ability of Indian
ers are more likely
and Roorkee, UP and
uipmen t . However,
,.
0 poor practices in
ng them between
the
. -The Bull’s Trench kiln is the inli’ovation with most promising
the equipment e‘ncountered in India and Pakistan. At prmnt
large containing a quar.ter of a killion .brick$ and firing 60
be able,tb function properly. ‘i%ey also pioduce a variable
of ‘control and fluctuating performance
with cha<ges in win
0pprovide a dirty and dusty workin
’ establish the same benefit of conti
‘cq,ntrol and conditions would not only assist the’ 1ndian.i
prdn@ing technology to tran9fe.r to other locatibns;gai
, fQnctiQq? efficiently with a variety of other fuels’as well
e
;!
I
r more bricks a week to. ’ ’
product due {o difficulty
d humidity. Mdreover, they
kers. Developkent
work io
,_,
ller output and with better
’
stry but also w’duld make ri
ularly if the kiln coLild be’ made to
.’
*
.
INDIANTRADITIONAL
c
BRICKMAKING
,
-75
.
’
A
*
--
b
,
-
.
-
k
!’
.
.
Central view of plant sho\?ing movable metal chimney alongside
Note covcrcd production
Wilding on right side ol’ picture
Vacant chambers 01‘ Bull’s Trench kiln taken I‘rl)m !hc. point
towards the corner where the lircd bricks arc heinp drawn,
,
pcrmclncnt
whcrc
the dr!
brick chiriincy.
brick5 .Irc hcinp wt. I~wkins
.
.
.
--
r
,
,m,.‘.
‘*
’
I
I,
-
.;
-
k
,-
-.
*:
.
,, .’
--.
INDONESIA
One of the parts of the Indonesian archipelago where brickmaking is an established indigenous
industry isBali, where families of.rice farmers frequently undertake brick prdduction
during
slack times of the year between rice, crops. Production takes place close tb public roads fo
allow access for vehicles bringing firewood and taking away finished bricks. The methods .
employed while similar to those of Irian Jaya and other- parts of the country aie far from
’ ty,pical of other developing world applications
‘and are summarised as follows:,
“‘
D
.,
t
-
3
!
Chy winning qnd brick moulding - The Indonesian biickmakers regard their material
in the ground as teady,‘prepar@clay
and deliberately keep the shallow clay ‘pits filled
with water so the’soil stays moist and ready for moulding. With clays which have a
potential fo? cracking, it is nbrm’al to add chopped i-ice stalk-s or ‘lalang’ (a sharp-leafed
hill grass) to th&.clay which inv&es a q&k mixing pro$ess with hand tools carried
I
.
out ifi the pit. Bricks are moulded in fives using’s mould which is operated by two
peofle and eonsists of a straight through frame. The bricks are moulded directly onto .
._
theiground and the mo’ulh left in position for some time so that the bricEG@jin$-~e
,.
dr ing process while actually stiil in the mould. Then when the bricks begin to shrink,
r:
1 .
th i y-detach themselves from the sides o’f the mould and the operators lift this clear
anld set it dob n in the next position. With several rtibuld sets the brickmakers can make
/
”
a riound 500 bricks in&)i.y using this method. The other b&kinakers
who leave the
, G r-q’ould oq the groundi$%?‘those of Lesotho but-in their case the moulds become free so
..
.
_
quickly that only two-sets need . to be”employed.
.:j
’ /’
.
,,
__ --- -Drying and firing - The-bricks continue to dry, lying flat on the ground until hard
k m-~‘.
.I,
* ‘_ Ienough to handle when thdy are stood on edge in a low stack to cptiplete the drying
‘.
process. Surprisingly little distortion takes .place during th: drying process $lich must
*I
t
be by’virthe of the clay and only minor moulding faults such as turned
Corners
:a
occur. The kilns are small scale ‘Scotch’ type units +h ope+n trench fireboxes able
to bil’rn around 4 000 bricks at ‘a time. The wood-firing process is extremely short,
lasting for only 24 hours and the bricks tend to be,imderbupnt,
signalled by the fact
that,the brickglakeis cover the finished products w,ith grass to avoid their bking
/
.
damaged by ‘heavy rain’.
.-
2
I
‘71’.
,,
\
up
With the type of fami$l%%%$&irig
described here, it.is quite apprqpriate for the process
to be an intermittent
one as the. people concerned are not dependini on brick production
fortheir livelihood but i&ead as a means to gain-a little extra cash,income, There are no
doubt *ays of improving working arrangements
which would enable the same group of
Keople
to
produce
more
bricks
in
the
same
time
or
the
sam;e number of bricks in less time but
,iP
.on the whole the occupation appears to”be quite a congeilial one in the climate of this area
i
and not meriting a great deal ofr$odification.
In areas where the demand for brick outstrips
the
dapacity
of
this
highjy
int’or$alrindustry
to
supply and there is a l&g term need to pro.
duce la,rger quantities more effic%tly,
a whole range of more productive methods should be
covered drying, wheeled trucks for brick and clay
. introduced, incltrding sandmoulding,
‘I’
movement and laige, fuel-efficient
clamps.
\
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:
A
i
c
:
a
,
.:
BRICKMAKINGIN
n
CHINA
'
:'
)
I
c
:
OTHERASIAhTATES
In the. remainder of the continent, brickmaking varies sharply from location to location. In
IRAN the methods employed are similar to those of Turkey and India with both sand and
slop moulding in use at the forming stage and conventional
Hoffman and open top (Bull’s
Trench) Hoffman~kilns employed to fire the bricks as well as some coal fired clamps. A
major new investment is now also taking place involving co id truction of alarge factory with
transverse-arch
Hoffman kilns and mechanically
pressed brick production.
The states of
MALAYSIA mainly build in non-brick materials but that brick production which does fake
place is mechanised with extruded wirecut bricks fired in tunnel kilns?$n PAPUA NEW
, GUINEA there is little or no indigenous brickmaking of the type described in Bali, but
bricks are made by some government bodies such as.the Prison Service at Bomana and elsewhere. The technology here is based on a locally made hand operated brick machine and
handmade bricks as such are not produced. Slopmoulded brick production has long been an
indigenous skill in CHINA and instances’of this can be seen in the New Territories of HONG
KONG. No doubt there has been considerable development
of labour intensive brickmaking
---ski&in communist China but no recent published information
is available for this review
apart from an inte.resting co-mmune’painting
which appeared in a recent exhibition of
workers’ art. From thjs can be gleaned that the brickmakers are operating a multi-chamber
continuous kiln and’move bricks about in a variety of hand trucks, usually at a run!
l
i
.
HONDURAS
Most of the Third World traditional brickmakers tehd to congregate in special areas such as*
river banks adjacent to larger population centres. Accordingly they rely on the,‘city as their
market and the people in smaller centres in rural areas generally do without permanent
- .
materials w&icll are regarded as financially, out of their reach. A notable exception to their
pattern exists in Central America where it is commonplace
for small towns arid even villages
c
to use locally made*clay bricks and hand moulded tiles in the fabric of the humblest dwel.
ling. The technology
is. most well entrenched
in the countries such as Guatemala and.
Honduras with a strong Spanish tradition. Unlike much of Mexico to the north the abundant forest and high rainfa{l provide both the opportunity
and the need to produce permanent materials to increase the durability of structures.
‘I
tile industry in Hondurai is extremely widely dispersed and, unlike most spontaneously
evolved activities of this kind, has invested sign$icantresources
to
assist prpduction. Virtually :a11the bricks are fired inScotch
kilns or at least on permanent
checkerwork
fire grates with side walls. Many examples of. production
buildings have been
” constructed specifically to house brick and tile manufacturing
activities. This contrasts with
the broad commentary
on most of the world’s traditional brickmakers
who are under- ’
capitalised to the extent of not even using wheeled truck.s to move materials about.
, *.
/
.,.,,Another feature of some of the traditional plants ii I-londuras is the existence of properly
L, ‘constructed pits for tempering the,‘clay prior to m&ding.
In other traditional industries
it is more normal to mix the clay in the quarry often on the same da.y that the mate@ is
used for brickmaking.
Apart from the difficulty of measuring quantities and therefore
controlling moisture content, the practice of adding water in the quarry unnecessarily
increases the weigh$of material.to be brought to the plant, by 20-30 per cent. This is an
important inefficiency,
especially if water is available at the moulding location itself, from a
well or by mains connection.
The Hondurarrpractize
of preparing clay in tempering pits
c
within the brick production
area is both more efficient and leads to better qu’ality control.
More than usual care is taken by some Honduran traditional brickmakm.products
it
which are as accurately formed as possible. However, instead of modifying the moulding
method from slop mouldingso
as to produce a better shaped brick ‘in the first place, they
.
usually fettle the:rough comers and edgesafter
the bricks have dried.
.
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5
1
HOMDVRASSMALLSCALEBRICKPLANTS
.
I
I-l
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.
l-l
l-l
r-l
l-1
I
Bricks
Moulders
drying
on the floor
Brickworks
layout
make bricks
‘.
‘9
:.*(
.,z.
HONDURAS
(1
,
.,..,.
.I.
I
+---I
SEMI-MEC‘HANISED
MEDIUM
SC’ALE URICK PL&@
-J
4
.1
I
Hot exhaust
through
Ai;
preheated
passes thiough
bricks
Cold
air enters
upper
a+, it
hot
_
*
heating
gases pass
bricks
II-+
chamber
them
prebefore
fire
-
kiln
r feeding
sawdust
Fire zone moves progressively
over several days
up kiln
-
into
firinn
kilns
,,, ,SSyl.ll:ld
, .A design of Eu;ropean origin b‘uQthe semi-contin&us
units_gre derived from prdctice elsewhere -‘probably Japan where simi &.uniis are known to, Fave bqen used. The desiin consists of a
straight barrel arckchatn y t r co‘nsttucted*on slopu7.‘gland so that the kiln floor runs uphill
in a series cif steps:The
semi-conti&o~ls
firing is achieved by beginning the bum iri the
$
,.
i
lowest
chambet,
then
progressively
dra’tiing
the fire gr\a$lually ‘uphiil’ by injecting new fuel $
0 *3,,
IL. into the cl;lamber just ahead of the fire. Ond‘e-a,,.fire is bLirning in the first chamber of a semi:;;;;;;:p.Lc+J.‘1,LV
- -----coti-ti,nuoljs
kiln the sm.oke passes thi-ougll. the cold bricks“in front of the fire and so preheats
they
savjng
the fuel which would have been needkd f&r this. Subsequently,.after
the
,:
tire has passed further,up the kiln, a second form of he>t?~chang~~ begins to take’effect.
The air needed for combustio11 of tt$e fuel enters the kiln athet ..tottom eld and before it
,’
il
reaches the fire iq passes through the spaces between the bricks‘i,?,the
lowest chamber
which were previously being fuelled. These, bricks still de’ing red’hot,pPe)<eat
the air before
,’
,it reachas the fir,e #- again eailging a jsignificant saving in thi amount 6f fueY-Feded. The
h~t&eha@e
process contir&es u&l the fire reaches the-top end of the ki1n‘an.Q is allowed
The combination
of preheated kiln$air &id ireheated bricks rr$akes it all.tAe m$;e p&i&?\,
to use for fu‘el mfite’rials such as &dust
which do notbmadily
whe&injected
I$&,o :kr \
. ,.
,a cold kiln chamber, but ignite immcdi’ately when in contzict with a red hot aimospher&
1
\.I,,
i'
- Sawdust,is ple1jtiful in coimt ies sucjh gs Honduras with a timber extraction $%I,,sawmilling .
‘p
‘\
c
industry for domestic and export mF&e’ts.
n_
Some ijl\‘estment has tak&place
in/ mechanised forms of brick production usi1)g import’gd
’’
Spanish clay preparation and tSstrusionplants.
The products sell readily because df t’heii ‘,,
reglliarity ol‘,form and ‘machine produced’ appearailce but the price is
to three times tl\at ’
of the t.raditional handmade brick, reflecting the high, cost of powering aud ma ‘Rtaining the ,,
mechanised pyoduction lines. It is significant that the’ mi’chine made bricks in Honduras
are priced at much the same level as bricks,made in Europe, whereas the traditional hand’
made pr6ducts are’ far cheaber than anything rn*
iq industrialised countries. In the rural
‘,#,
areas of Honduras, unemploy1tient is rife and.labour cheap. Without the brick and tile bn\
dustry the situation would
be mt~h worsq.,aild more of the population would h&e mov&d
‘..
to the already overcrowclcd cities.
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9
THECARIBBEAN
i
8
<
There is.little evidence 01’ incligiznBus iraditional brick&king
on the small islands bf the
Caribbkan gnd predominant
construction
systems use ma(nly timber or conciet$
One
instance wliere.,clay brickmaking has been established, but not in B ‘traditional’ form, is in
..
the n’orth west‘corner of BARBAD,OS. A !abour-intensive
plant op&rat,ed for s.e&ral years on
the island and on the basis of its success investment was made in a:more mechanised unit.
This is clearly,being run with more than usual technical competentie,
as the ptodu&s are
well formed and ,consistently fired. Nevertheless;aas with most mkchanised units located : ’ .
remotely from machinery sup)liers, the Barbados,factory
had froni time.6 ttile incurred
’:
long stoppages due t.0 breakdown of $&al
&ompo&nts whi:h r~_cE~li&replace’tient- by-i&
.~~
. pqrted- spare parts,.- The hi$$ fiked cost’ T&els’of the ope&tion f and @le.$a~ure of the firi”,g $.l’ h
,
,
s--+. ’
. :,
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4
‘I,
i- -I
MEDlUMSCALEMEC~ANlSEDBRlCKMAKlNG
INBARBADOS
.
e
f 1
c
a
(with oil) have been factors
inhibit sales at all times
stocks becomes
forcin&u
charged fdr the products:Expensive
bricks
with large’volumes
of unsold brick
when the building trade slows down.
s
product developmelit work
G&Sand, tiles and tlie development
of
7
which h&e no brickworks.
EkICAN STATES
OTI-IiR CENTRAL AND SOU
evelop’ng’ world is not so. well documented
as that of
Btickm&%g in this paft of t
and-geo & aphical reasons the industry is much less wideAfrica and Asia, and fti
ortugusejnfltience
over most of the area has resuLted in a .
spread. The $trong Spalii
mic building materials that are proquced deing mechanicallyhigh proportion of th
s. Solid masonry tends to be either concrete or adobe - muc,h of.
extruded hollow clay
aking using similar slopmoulding .techniques to ,those employed
the Adobe brick
e denselyefores’ted areas, buildings are largely constructed
out of
over much of A
e exceptions to this pattern are known and, there are probably mani
timber: However
umentation is not accessibleat
present.
,,,
m&e for which
;
’
6
.
The Goveni
ent ?f GUYANA had conclvfled that many of the wooden buildiqgs common
eas of the country were hsrbouring disease-carrying
pests and’s0 decided toen‘in poorer
-‘.
Help was enlisted from the’ American
:. courage; -i e use of bricks for domestic construction.
ndu$-y to second staff to help start brickmaking projects. The progr3mm.e is underto hz@encounterecl
some marketing difficulties from builders reluctant to us6 bricks
a
d
of
cbncrete
blocks.
Meanwhile further *long the coast in SURINAM, one factory has
. 1
?
en constructed av,d put’into operation with i Nethetlands designed continuous chamber
.
Lima, PERU, conimon b,rick production is und.ertaken.on
a much more spontaneous,
bas,is. Here enterprises exist which are novel from a commercial Qdipt of view/and inight
//
G .,
proyide a lead by which other developi’?g countries’ plants
>e qrganised. The system ;
.’ is for a kiln owner to a,ct as a nucleus to a series ~fsmall brickmakingco,!lcerns.
These work
’ .
~,
groups produce slopmoulded
bricks on th’e conventicmal open box patte,m and then II
sell their production
to th,e kiln owner. He theti oiganises the firing, using locally mined coal
’
and thus adding value to the b>ricks, and resells them on the commercial market at a profit. From . 9
a technical yiewpoint, Lima is an [deal bri,ckmaking centre wit-h virtually no rain but plenty
,.
of water (brought from the mountains beyond,+
dry- coastal plain).
,’
1
*
could
MEXICQ is adother Latin Americali country with tin established handmade brick tra’dition.
.
The tendency of the svall family plants to .underfirC $eir products caused ‘mexican 6rick’
to be a term indicative ,of ti soft common prick. The ti’merican infl\!ence iri .the hrea has COJIfributed to the successful introduction
of high technology &fits particularly as the lower
. .
labors tests in Mexico have made ,it a ,worthwhile business exporhi,ilg extruded wirecut,
tunnel kiln tired bricks fo the United States: .In sucll.circdmstances
heavily mechanised
production becomes worthwhile and over,shadows the traditional industry; although slop- ‘L .
moulded production of adobe bricks, typical of practice all over Latin America, continues :
- ,
in the’ rural areas. For a different reason,, the prosperity brought about by oil,‘VEiNEZ.UELA
has also opted fFniech’anised
prod&ion
of c&amic prodncts. Th’&e. are mainly hollow . ’
clay blocks but some bricks are a!so produced in small factories. The climate forrbrick‘:.
makers was fqr a long time ideal, with generous Government
grants to assist thkm to purchase
capital eq’uippent, and butane gas‘.for firing li$e;ally given away.by the oil companies $.a
was
time ivhen theonly other optidn was to flare this fuel off-at ,the refi Revy,. The di@iIty
that t-he main mark& were in the north arouud Caracas in a sandy, rocky area, *bile the
’
i
clay deposits lay to the south west around-Barquisimeto
and Valencia. Thi%situ&c% has not
’ favolired the qstablishment of an &dige’nous or‘b-aditibnal brickmating
industry but has,left’
.
; : the activity to businesses witli. the facilities to organise i’nstallation of mechaniCB1 equipment,
?
’9
a5
ri
r
.
.
c,
‘L
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I
‘_-
_.
.
-
..
i.’
-..
*
,
j
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c
.
*
‘,
’
i- - -.,
i
.intermittent
and tunnel kilns and the’means to transport biicks to the markets in the no&h.
In the ineantime, the stiall’indigqous
technology
oflopmoulded
adobe brick production
in rural areas has seriously :contracted..Much
of the brickmaking te,chnology employed’in
Venezuela is, unashamedly energy’-inte?sive with small ceramic producing firms posseising
5 000 litre tanks of lpg,‘.which would cost i fortune to install. and repeatedly fill even in _
Europe let alone ifi the poorer developing countrie’s. Pioducts are burned in highly inefficient rectangular inter&,t,tent kilns with no proGision for insulation 0; waste heat%
cirdulation. The changing si!!uation of energy costs with increasing ‘fa&ties available to ’
trans-ship propane and buta le to overseas customers could’potexitially
r,uin brick producers
of this typt: in oil-rich dev loping countries. Having committed
themselves to plants
designed as if energy costsJb id not matter, they coul? now find themselves increasingly
ic”cost for these fuels in world terms.
having to pay a more
I
Such a situation might, in
lead to development
of a more frugal indigenous
indjstry, wore like those described in preceding phragraphs.
L
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c
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ii
brifk
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‘1
PART E. PRIORITIES FOR RE$EARCH @D DEVELOPMENT
,.
P
8
General cdnclusions ; I
- The exerciee of describing aid assessing the main Ik&ical
problems of traditional brick
industries in g gre,at variety of developing countries has,pevealed several .reptating tedhnical
problems which nobod$ has completely solved. ,Indiv$al
remedies have been found which
suit p@cular
circumstances in dne or other locations&tit
few of these are in a‘ form to suit
). ..&.
‘.I
imtiec&te
application elsewhere.
.I
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P
r
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.\
-
:
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, ‘.
.
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c
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Other than the tqtal lack of-brick clay, fuel or wa-+er there appear to be no situations i:.I 7
developng’countries’
where absence of a suitable processing technology
has .held*up the- .
develofiment of brickmaking altogether. Where people have f&t a need to prod@e a pertianent building masonry component
they have’$tially
found a &ay of making bricks,,..
i~
from heavily forested areas to semidesert,
using fuels ranging from conventional
fo&ij,; .-..
- !_
,
i‘fuels and firewood ‘to waste,‘vegetable and animal matter.
*
- c
._ *
...a’
;*c
-\
~_.
-:-_
’
The pfevailing need therefore a;pears not so much to create technologies which w$uld enI
*able people to make Qridks who where previously unable tb do-so, but m&e to help people
‘“;
,-,’
make better bricks, more efficiently, less impeded by climatic changes and in rnqe con’genial
conditions. These four httributes are impoitant
for the follo$ng
reasons:
a
’
.
.
.
.
Better
bi’&ks
will
increaSe
the
range
of
abplications
f;o;‘which
they can be used kg load.
bea’ring brickwork’in substitution
for steel or reinforced concrete frame Con’struction”
’
of multi-storky buildihgs. They will speed the building process and reduce the cost of. ’
bricklaying ey reducing the amount of work needed to-adjust for inaccu.racies bf brick
size and sha$e. If the dimensions are *more reliable., bitilders will be able to reduce the’
L
.thi&ness df the mortar joint between th&’bricks which will in turn reduce the
’” _ : *
’ ~eement.requirenient
&tl~con~entional
bric,kla.ying, and increase the possibility. of usihg
;
I
r
r’nortars which exclude ce’ment altogether in certain applications.
-0
.
1
_ 4
.‘
k’.’
,
More effidienc; +,fhe use pf producti0.n factors will iinprove the economies of brick- ,, 1 *(‘
riaaking and’ &able those ih. the industry t,? mhke a’ better living while consuming less
resources. This is.pal;ficul&~y important in the.q&$iog
of fuel if this is obtained $ a
‘.
.
sc’hrce or non-renewable
forrC
9
;
.
.L ..
9.
.I
The wet/dry, seasonal cycle in most developing countries is ve& disruptive to :br;iEk
. . ’’.
pi@&tiopeyen
where cdvered working:areas have been cbnstructed. ,I&&& humidity
,
impedes the essential drying stage in the process apd excessively low humidity causes I
9
.‘loss& by cra.ckibg the bricks, while r&n desti-oys%.nfired bricks left out’in the open.
. .I
I
. s
r
Improv.ed working eliviro&nent
arid reduced tedium iI; tl;e production
processes -of
_:
:.
traditional brickmaking will fompensate
for one of the major attracti’o;;
Gf high
ti
technology
brickmaking wlii& normally is utidertak&
ttidet cover and substitutes
’ ‘3,
Y capital and energy-intensive
machinery for manual tisks.
.
Atiy ‘Fajqr advances in these four fields tiill also have an effect on
of labour-intensive.-brickmakin4
and thereby will influence the
to those m\arginal areas WheTe previously.thesetting
up pf an industry was *not quite feasible ’ ” I
i, q
:
‘; as a propos\iti&.
In
*.-*
“,I,
-+
0:
T
*
Imprqvedfenh
to cla~‘winn,ing &cl” preparation
* ,Examples froin the description of brick industries of Gveral’of the
identified, tfie,ne’ed for a method of-‘&gging the soil which ensures
iS takei? from all the different !ay~%. This is so that each batch oFraw materials reaching the I
,_
1)
‘,
I
I
a,
d
I
.-
.
‘,
,
D
production stage has similar moulding, drying and fipng properties in orde; ;o produce a
consistent product. In highly m$chanised brickworks these consistent pioportions
are ob- *
tained with the use of shale-planers, multi-bucket
excavators or, a little less effectively, by
dragline. What is needed is a hand-tool or simple mechanical device which will rn@tihe-‘-actions of these heavy machines and, ideally, blring the dllg-mat&alup-tC~5und
level as ’
well.
I
In many locations, the woik of obtaining q&ontip;lal’suppfy
pf water with k<ich to mix the
clay.amounts
to a major task with a lot.of ted$lm where people have to carry heavy cans
from a distant squrce. Where motoi vehicles have to be used for thi$ purpose they add significantly to the cost a,pd ,increase the reliance on a facility which is not nedessarily feliable.
A fechhology tb o‘btain ground w’ater‘using a hand-powered
or wind-powered
pumping
system from a borehole pr well would be a great benefit to rriany brickmz&g
ventures as
would a ‘sim.ply constructed
facility td store this water
and catch any convenieyt rain thaf,
.
falls.
During
t!le
wet:seas?n
the
same
equipmeqtG$d
to
obtain water at other’ times might
..
be ad@ted,to the task Ff pumping water away from the clay pit when flooding is a cause of
*
.>‘production hold-ups.
r
’
-.
tThe.,i$ed to reduce the-material lump size;il; the preparation process is generally performed
by m&zhaliical mix&s; by treading w. h,bare feet’and.by tempering (leaving the clay to
.
. ‘soak for 24 hours &hj.
Fu11 mechan ‘ation is likely to stay beyond the reach of many
L
brick industries for a long time to cd e but the puddling world using.bare feet is a tediousj
B
tasb,for yJhi,ch it ,&ould be h.elpfut to obtain a substitute. The hammer hoe iland tool of the
M,alawi.hrickmak&s iocs’part of the way to sol;ing this pfo,blem @tit there are no doubt
many materials which wi,iI not be as compliant as ‘llle local clay with which thi‘s tool iS now
used. ‘One possible avenue of research and development
cquld be td c’ombin’e. the dry gsinding process used by inany mechanised brick plants with the tempering method, ie to, develop
a systegl bf pounding clay into a smalrparticle
size then leaving it to temper with tiater
.zidded in a suitable storage pit.
ID
:
‘$‘\
I>
lmprovements
to brickmotilding meth:ds
^
., s
:
II
,
I
.’
Developments are well in hand to enable unskilled workers to produce an accu%.tely shaped
bric.k- %in’g a sand.-lubricated, self-releasing mould. l&is may turn out to be a widely ac&ptablesolution
where sand is readily available in the area oft& main clay depdsit. This ig not
uni\sersally the case however, and it is probable that many brick industries will consideytltey
.. . have no option but to continue the practice of slopmoulding using only wat~he~m&ldrelease. A moulding system is therefore needed which will enable thes? industries to produce
.
better bricks without need to u’se significant amounts of any material other than water and
- --._
‘?iiE%ii~ay
i.tself. The key to obtaining a well shaped brick with current technology is
the lubric&Gg Eipr-or-film
of material separating,t)e’clay
fro; the side‘s of the mould
or exti+r
die..Without this the clay sticks and drags on th: side of the former and the
brick beComes distorteb.,
i-
With sandmoulding the sand-on the surface of
*tee brick’@s as a lubricant eqabl.ing the brick
to drop clear without,d&tortion.
e
I
This means that theclay can be handled fairly
dry and if set down on a pallet as- shown in the
diagram, the bricks can be taken’to the drying
~
floor in groups by truck, and can be tu’med.hnd
stpod o,n edge to dry.
.
:
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-2%
--‘---r
i-A
In most traditional brick operutioljs only water is uscil ,?nd is mudh less effcctivk tha; sand
as a lubricant*an.d only works if the clay is cxtrernely \nlet and soft. Ifmade any drier the
brick @sorbs:the water film before it. can be released from the mould anti-sticks. If the
E
4
=
d
-
Lb=
.
*
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‘- .
~ETT~RMOULDINGSYSTEMSPERM~TTlNGIMPRINTOF~AMElDENTlFlCATlONON~RlCKS
*
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P
/ /
_
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2
F
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r
. . ?
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.
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n
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_
_
“.____
.-
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,
9
*.
-
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,
moulder’s clay clot is coated with a differe t liquid, suc’h as oil, before t&owing into the
mould, when mixed back ,into. the clay an P -oil left on the offcut will ‘tend to cause laminations in’ subsequent biicks. This alSo happens with sand:
2
,
’ :
’
With slopmoulding the clay r&eases itself from ihe
’
mould by bending in the cen$re %:
which pulls the ~-- @fLL--!~~
ends of the brick away from the surface of the
r,nould. This is then lifted away leaving the brick _~__ii .’ -‘in position on the floor.
.
I’
..
The clay is always made very wet which means
’
that’ it .is too soft to be handled subsequently
and
must be left flat on the ground until dry, using
more. space, taking.longer to qry’and dften be,coming further distorted.
:*
A new improved
fiQe features :
method
of moulding
with j;st
---, ;-;-
I
,_
!
clay an,d Gater demands
0
development
of
The facility to mould with stiffer’clay so that ,the brick can be set to dry on edge rather
than on the flat to lessen drying distortions, (attempts to use stiffer clay with the piesent
kmethod woklld just lead to the brick sticking fast in the mould).
/
.
The means tQ avoid the splashing which makes present slopmoulding
such an uncongenial
1 6peration.
.J
Q’
T
‘f
*
I
/
A technique for preventing the brick from picking up surface material from the drying
.~_. - .> -- :-. .___
~-- ___~
gr<und.
’ ,, _
~- ~~
?f
:.A
‘j
The f&ility tp handle the slop bricks when still wet so as to remove the present inefficient piactice of carrying the-bricks’in the mo&d to the drying ground.
h
.
The facility, to print the brickworks’ name or manufacturers’
mark in the frog of the
-’
’ I’
I brick because of the psychological effect this has on attitudes to quality. Managers and
1;
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workers seeing ‘their’ bricks being-use&in -build&+~
+e&x3ense-of-responsibi%ty
’
.-than they do if once despatched the bricks become anonymous.
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hprovements
to drying systems,
The priority for improving methods of dr ing centres’on the need to adjust as far’as pdssibie
for the variations in na.tural conditions. H ghly ‘mechanistid b$ckmaking
achieves this by
creating a totally artificial atmosphere of ow humidity, warmth and air movement, by.a
.
combination
of fans, heaters and system to re-circulate ‘kiln waste. heat. For traditional
brickmaking the most promising line of a 1 proach is in the design of a building with special
featuies which would enable it to either enhance or restrict the movement of natural air
,
currents, to adjust levels if practicable, and divert some of the waste heat from the clamp to
assist the bricks to dry. In some countries brickmaking is likely to remain $n essentially.
itinerant activity so the .need here is for the drying building to suit being readily taken down
and moved to a new clay deposit.
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During the p&iod of the wet season in most developing countries, the weather pattern
‘includes plenty of dry spells which need to be fully utilised, in accelerating the
brick drying process. One probed&e already intrtiduced into a few plants is to move packs
of ‘green hard’ but still damp bricks out into the sun, using a spec$ally designed truck. This
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DEVELOPMENTOFTECHNlQUESFORWETANDDRYSEASONDRYlNGOFBRICKS
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activjty could he affected by the condition of the gro’6nd but a truck-with kufficiently la’rge
,
yhe$sshould
be ahle+ to, Cope with conditions in most brick yafds. This does not yet solve , i:
.
- the pioblem of newly moillded bricks which are too wet to stack and so a ‘system.of
H
movable racks is required‘tihich
would facilitate the rapid movement of wet bricks into
..
.
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external. drying conditioes to take advantage of a dry spell in the rainy season.
.
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a -. DeLelopments so far have o_nKygone. part way tq evolving a suitable system for mouing’
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bricks, and more’work along these lines is required togethei with the $evelopment
of an ad7
j&able and ,pos.+ibly a transpdrtable
drying building.
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Improireqtents $0 the method? of firing bricks ’
-_
The greatest emp!Tasi,s rieeded under the heating of firing is to minimisle the fuel require., ment where this relates to coal or oil which have t9 be purchased, or firewood which needs
‘*
in conditions of increasing scarcity. A major contribution
to
.-._ ?:,:,,to be gathered, frequently
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!.
firing efficiency is to ensure tRat all
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-fuel is not wasted completing a piocess which
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The, n$xt priority is to increast the
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achieved in sevefal ways :
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Introduction
of continuous
firing alon”
would piovide thi: greatest step
immediaiely
available for those inhus
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which suits top feeding. THe proces,s may’also be feasible using waste’materials suC11as
‘qt..
’
chaff or sawdust and this-.should be invest\gate.$ Continuous kiln firing either us’ing fixtii;$.
__..’
arch Hoffman kilns or rubble-topped
Bull’s
Tre&h
kilns
demands
the
establishment.of
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enterprises large enough to generate the 10 000 or so bricks a day needed to keep sucj~
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kilns running. This is+far too,large for many situations..a’nd a new design of sniall scale
,-$
continuous kiln is needed and in particular, oqe~&hich can be fired with scrub timbqr.
,,
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This development
needs to be given a very high briority.
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,Pairing with qther indi!stries whose processss c<$lld have complementary
aspects should
be investigated. Charcoal production gen&atg$ inflammable waste gases which may,b<’
usable for firing bricks. Animal dung is a p.otential soilrce of methane as well as.. fertilizer,
.and the former might be taken off to-burn bricks leavirig the latter for argicultural use. z
‘- .%
These technologies merit early development.
7
.A
Incorporation
‘of carbonaceous matter into thebrick clay itself is an establ.i$ed means of
‘reducing the external fuel requirement but little is yet known about what the ideal p$o-.
pdrtibns dX different materials should be .&hen.appliecl to clamp or simple kiln burning.
This could’also be-the subject of a useful study.
In the operation of woodfired clamps consideiable fuel wastage is caused by poor insulation of the clamps against loss of heat through surface radiation and through exposure to
the cooling effect of wind. These can be remedied by operation ofi known methods. H&we&, more than any dther cause, the major loss is from too ‘much ixcess air being’drawn
into the clamp through the open ends of the firing tunnels. This calls for thie development
@f.an efficiept heart11 and grate able/ &burn irregularly’sized
pieces bfawood whileJetting
through the minimum amount of excess air.
I
The most extreme solution where all types of fuel are becomillg too scarce to burn b&ks
*with, is to seek ways of continiling brick production but to abandon the firing stage&altogether. The research and development
effort here will need to go into ways of stabilising or protecting unbaked brick’s so that they can still constitute a permanent building
m,aterial.
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IMPROVEMENTS TO TECHNOLOGY
ADDITION OF COMBUSTlBiE
OF 1~111
MAtERIr\LS
AND CLAMPS
5.
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to handling systems ’
, n
,?i,evkls of productivity
in brick, plan;s va’jr over an extreme!y iide range aikas’de+ibed
i‘n ,
Parts B and p. In th’e areaSLwhere fabour is’most “Inefficiently,used
the factd; Which is ..’ ’ 1
$A ; usually responsible for exc&sive maiming is the movement’,of mg.terials and bricks in
between Ijrocesses. Und.er c&e system i wo-rker’s t&e inay be occupied moving, only two . :
, :/bricks w@le inder another a simple piece,bf eqtibmeni
enables. a similar man to transport
- the movement.of
.
40 .bricks. T,he ‘same ran@ of efficienc$;oc 2 urs III
clay and of water.‘Work
place layouts are not so extreme i? th_eir range Qf efficiencies as t,lae process flow is a simple
_
&and
it is difficult to take, too many,-urlneces‘sary journeys in the course-tif an activity.
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rovemknts
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/The gr!eat ianie of pi‘oductivity obsewed between different6traditiolial
brickm@ing enter” prises each operating with o?ly rudimentary
equipment indicates that the& miist be consr+Iei’a’ble opport&ties
for assisting the wqrst performers to become more efficient. Whqt is
ineehe$ is’a Bully integrated 4rtindling system using simple a$‘r;obust
equipment which inthat-people cali’do y,ithout liardship. In developkent
. 1 “!&&es the $io>mt-of’effe&e”work
’ bf’this equipme!it f?l attention sho’llld be given tb the”technical proiess requirements out/ II&
.
;,hn‘“e d
$+; 1~~-~~onmentan’dof
rnake$he occupaergoliomics w!lich .--_
.s
Cons hs*congenial as possible in jhe.conditions.
prevailing.
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Priority projects
Of-&he various ifems in ‘&e tec’llnoldgy’of.t~dditional
brickm:l,kiiig \khich
re:earch and development
work t.o bring about il!iprovemcnt,
three items s
_ quiring tl?e most urgent-httention:
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A moulding system ‘able ;o pyo‘;uce an accurately sh
-brick which &stiff enough after &oulding to stand on
handling in the $r&n state, without damage.
,
I
q ‘A simple grinding and stscening system capable of red
down- to less tL?i 3 mm di>meter generally. or less th
the clay, coupled with a practical syste.hJ for wetting
1
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110lirs.
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.& simple small-scale c.ontinuous kiln achieving,bette
(intermittent
kijns aqd clamps arid which is capable o
‘2 either as kil;i fuel of incorporated
as carbonhceo&
matter in the clay itself. ,.This development work could also include improved dtsigns for a h.earth and &gratefor more efticient
wood firing for use ‘with eitller kiln or clamp.
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