Development of prefabricated facing brick panels

1 .b . 1
DEVELOPMENT DF PREFABRICATED FACING BRICK PANELS
K, FISHER
Redland B1'icks Ltd. , Horsham, Sussex, Great Britaú,
B,A , HASELTINE
Jenkins & Potter, Consulting Engineers , &ondon, G1'eat B1'itain
DEVEWP''ENT OF PREF4BRICATED PACING BRICK PANELS
ENTWICKLUNG VON VORGEFERTIGTEN
WANDTAFELN IN FASSADENSTEINEN
The manufacture of prefabricated brickwork panels has
been a topic of interest fo r some considerable time
amongst brick manufacturers and materia l users in the
Die Herstell ung von vorgef ertigten Wandtafeln aus
const1'uction indust1'y .
unter den Zieglern und den Bauunternehmern .
Following a b1'ief summa1'y of
Ziegeln war lange Zeit beliebtes Diskussionsthema
the va1'ious options available for panel prefab1'ication with an indication of related examples , the
Nach einer ku1'zen Uebersicht übe1' verschiedene
papel' reports observations of t1'ials carried out to
Móglichkeiten von V01'f ertigungen mit Wandtafeln
construct and erect a, se1'ies of panels built by trad-
an Hand Von Beispielen, werden die Autoren be -
itional methods under, controlled conditions .
richt en üb er Beobachtungen bei Versuchen, um eine
The
work aimed to provi de an opportunity to simulate the
Reihe Von M2ndtafeln auf herkómmliche Art und
on- site construction and erection of brick panels
Weise , jedoch unte1' Anleitung , herzustellen .
such as wo uld be used in a typical jramed structure.
Vier Wandtafeln wurden gebaut, die zwe i Wandta Four panels were built , comprising two sto1'ey - height
feln mit einer Stockwerkshóne von 2, 60 m umfassen,
(2 . 6 m) panels , nominally 3 . 8 m. long, to reproduce a
nominal 3 , 8 m lang, um eine typische Eckausbildung
typical C01'ner detai l with two spandrel panels along-
mit zwei langseitigen M2ndtafeln von 1 m hoch und
side , 1 m. high , 3. 6 m. long o Special b1'icks at the
3 , 6 m lang zu reproduzieren . Die Wandtafeln wurden
panel edges provided an aesthetically dis tinctive ex-
unmittelbar auf dem Beton - Fussboden angebracht und
pression of the joints .
auf beiden Seiten an SãUlen be festigt . Besonder e
Aufmerksamkeit galt Einzelheiten, die sich mit dem
Panels were positioned
. directly on a concrete floor slab and fixed to
columns at each end of the panel. Particular atten -
Aussehen, de1' Exaktheit und den Abmessungen, dem
tion was given to details concerning appearance , di -
Transport , und dem Anbringen und Fugen befassten .
mensional accuracy , handling, fixing and jointing.
Die FTobleme, die sich hierbei ergaben, wer den be spr ochen .
The problems encountered in satisfacto1'ily meeting
these r equirements are discussed .
1 . b. 1-0
LE DEVELOPPEMENT DES ELEMENTS
UE ONTWIKKELING VAN GEPREFABRICEERDE
PREFABRIQUES EN TERRE CUITE
BAKSTEENELEMENTEN.
La préfabrication d 'élements constitués de briques,
Het maken van gepr>efabr>iceer>de baksteeneZementen is
fut de tout terrps un sujet de discussion entr>e briquetier>s et entr>epr>eneur>s . Apr>es avoir> passé en r>e-
der> steenbakker>s en aannemer>s.
vue les diver>ses méthodes de fabrication de ces élé-
van de ver>schillende mogelijkheden voor> de fabr>ikage
ments , les auteur>s font quelques obser>vations quant
aux possibilités tr>aditionnelles de constr>Uction
enkele obser>Vaties inzake pogingen om op tr>aditionele
lange tijd een geliefd diskussieonderwer>p geweest onM2 een kor>t over>zicht
van baksteenpanelen, met voor>beelden, geven de auteUl"S
d'éléments et de leur> errploi , en r>espectant toutefois
cer>taines conditions irrposées . L'ouvr>age t~che de
tr>ouver> une méthode qui simuler>ait les conditions r>éel-
wijze , doch onder> gekontr>oleer>de voor>waar>den, slemen-
les d 'ér>ection et d 'emploi de ce genr>e de panneaux,
tels qu 'ils ser>aient utilisés dans une constr>Uction as-
Er> wer>d een poging gedoan wer>fvoorwaar>den te simuler>en
ten te ver>vaar>digen en te gebr>uiken .
en elementen in te bouwen in een typisch skelet .
semblée en squelette et ar>matur>es.
Vier> elementen wer>den gebouwd, waar>onder> twee met ver>Quatr>e panneaux fUr>ent constr>uits, dont 2 d 'une hauteur>
d 'un étage soit 2,60 m et d 'une longueur> nominale de
diepingshoogte (2.60 m) , nominaal 3,8 m lang, en een
3,80 m, deux autr>es r>epr>ésentaient un détail typique
3.6 m lang .
typisch hoekdetail met twee panelen van 1 m hoog en
speciale stenen op de hoeken gaven het ge -
d 'un assemblage en coin et mesUl"aient 1 m de hauteur>
heel een estetisch verantwoor>d uitzicht .
SUl" une longueur> de 3, 60 m.
wer>den dir>ekt op een betonnen vloer> geplaatst, en op
Des briques spéciales
donnaient au coin-même un aspect esthétiquement valable .
Les panneaux fUr>ent appliqués dir>ectement SUl" une surface en béton et attaohés de chaque côté aux colonnes .
beide zijden aan de kolommen bevestigd.speciale aandacht wer>d gegeven aan details in ver>band met uitzicht,
nauwkeUl"igheid van de ajmetingen, tr>anspor>t, bevestiging en voegen .
Une attention par>ticulier>e fut consacr>ée aux détai ls de
la pr>écision des mesur>es, du tr>anspor>t , de l 'assemblage,
des joints et de l 'esthétique génér>ale. Tous les pr>oblemes qui se présenter>ent font l 'objet de disaussions.
De panelen
den besproken.
De pr>oblemen die hierbij opdoken wor>-
1 . b . 1-1
INTRDDUCTIDN
1.
Interest in prefabricated brickwork is by no means new .
Early trials were carried out in the U. K. about 40
years ago. and development work was underta ken by a
number of brick manufactu r e rs in the early 1960's, but
few Df the resulting systems have been widely used in
the intervening years .
Dverseas there has been a steady increase in the use
Df prefabricated panels, notably in the U. S . A. and in
Holland . Some European brickmakers hold the opinion
that sooner or later, a large proportion of their output will be supplied to the construction industry i n
prefabricated panel form o
Several major advantages exist for prefabrication, and
a variety of methods can be used to manufacture such
components. Afte r briefly considering these points,
this paper discusses some aspects encountered in the
development of a facing brick panel built in a jig by
traditional methods.
between two vertical faces in a special machine.
Grout is fed into the top of the machine unt il all
the joint spaces are filled. Large pane ls that are
true and plumb, with perfectly filled mortar joints,
can be prod uced quickly.
(c)
Many early prefabrication systems were based on jiglaying. This involves traditional brick layi ng using
jigs to improve prod uctivity and facilitate quality
control o The method requires relatively simple equipment and production facilities. Thus the 'fact ory'
can be established either at the brickworks, the contractor's yard or on the s}te itself .
This latter approach, (c) , was adopted in the current
work .
ADVANTAGES DF PREFABRICATIDN
The major advantages of prefabrication over traditionally laid work cari be summarised as follows:
(a)
Work is carried out in a factory, or at least under factory conditions , thus avoiding the effects
of weather .
(b)
The materials used and the ac tu a l construction
process can be subjected to more careful control,
so that the resulting brickwork s hould be
superior to much normal traditional work .
(c)
With many systems, decora tive bonds, recesses and
other features that would normally be too expensive or time consuming in traditional work , can
be readily incorporated into panels.
(d)
(e)
Prefabrication can accelerate the entire site
construction, enabling earlier occupancy of the
building with a resulta'nt financial contribution.
Site problems involving congestion of materials
are eliminated. No storage is necessary on site ,
since panels can be lifte d from the lorry and
placed directly in position.
Naturally fresh problems are also introduced, such as
fixing , jointing and hand ling , but considerable experience is available with other materiaIs , and many
known techniques can be readily adapted for brickwork .
3.
Pa rticular attention was directed to the following
points.
(1)
Appearance
This is obvious ly of importance for facing panels , and
care was required with both bonding and pointing .
Bri cks used were sandfaced perforated wirecuts . Special bricks were used around the perimeter of each
panel , as illustrated in Figure 2 . Use of such units
resulted in a number of advantages, namely:
(a)
the detailing of the joint is facilitated and,
because it is expressed , the panel becomes aesthetically distinctive as a special product.
(b)
the risk of damage to the arrises is minimised
during any transit and placing,
(c)
panels can be used in both internal and externaI
corners without breaking the dimensional grid .
Figure 2 illustrates typical junct i ons between
pane ls .
(2)
Dimensional accuracy
PREFABRICATIDN METHDDS
zontal casting# vertical casting and jig laying .
Nu-
merous variations of technique exist within each of
these categories . Discussion of several of these
techniques is detailed in the papers listed in the
bibliography (refs. 1- 9).
Horizontal Casting
In this method the bricks are placed face downwards on
to a compressible sealing layer, in a horizontal tray
or mould. A thin grout is then poured or pumped over
their backs, filling the joints betw·een them . The
m~uld may be lightly vibrated to aid this process o
(b)
Description
The purpose Df the work was to carry out a small scale
exercise to simulate the on -sit e construction and
erection of bri ck panels as used in a typical frame
structure . The arrangement of panels is illustrated in
Figure 1 . Basically, it consisted of an L-shaped reinforced concrete strip foundation , with three hollow
brick columns , built off the foundation, together with
two steel channel posts . The cavities in the brick
columns contained reinforcement, and were gr outed with
concrete . A frame construction was thu~ simulated .
Four brick pane ls, two storey-height and two sill
height , were jig-built by traditional methods adjacent
to the strip fouridation by a local contractor, and
subsequently hoisted and placed into final position by
crane . Lifting was by means of canvas slings from a
steel spreader beam .
There are three basic methods of panel assembly: hori-
(a)
EXPERIMENTAL WDRK
4.
4. 1
2.
Jig-laying
Vertical Casting
Bricks arranged in a bond pattern are tightly clamped
Panels were bui l t i n spec i al timber jigs . Accuracy
was closely controlled. This is necessary where
panels are to fit into a modular grid .
(3)
St-rength
Adequate sfrength for the pane 1 is necessary to permit
lifting and placing in position . In finished work the
panel must be strong enough to resist wind, impact
loads, and frame movement . Reinforcing w·as therefore
placed at intervals in the horizontal joints, as shown
in Figure 1. The morta r used WBS 1 :1 : 6 by volume .
1.b . 1- 2
(4)
Fixing
Special fixings were designed to hold panels to the
structure. Figure 3 details those initially used.
These gave ris e to some problems during the first
erection trial, as discussed in section 4. and t hey
were subsequently modified as illustrated in Figure 4.
(5)
Jointing
Joints must exclude the weather. be simp~e and economic, with an aesthetic appearance, accommodate differential movement, and allow for the manufacturing tolerances within the framework Df dimensional co-ordination. A 'dry-joint' system was provided for the
vertical joints, using a proprietary filler strip.
The bed joint for each panel was made as follows:
(a)
two rigid packing pieces for each panel were set
and levelled on a 1:3 mortar bed at an appropriate distance apart.
(b)
After this had hardened, and when panels were
ready for erection, a 'ridged 50ft mortar bed was
trowelled between these support pads and covered
with a layer Df 'Hyload' D.P.C. along the whole
pane 1 length.
(c)
4.2
The panel was then positioned on to the bearing
as quickly as possible, 50 that the mortar bed
was squeezed out to provide a uniform bearing.
Dbservations
On the basis of the trial, a number Df observations
can be made, some of which would lead to modifications
in future work.
(1)
Construction
An improved building jig is required, the design of
which should not present difficulty. It is important
that the bricklayers have no chance to build a different number Df courses than required, as this would
affect the fixing positions, and must be avoided.
beyond the front of the c oncrete slab unless a special
flas h ing is incorporated.
(4)
The fixings initially used, and illustrated in Figure
3, were unsatisfactory. It is necessary for any fixings to cope with a degree Df tolerance, both in panel
size and position, and a degree of inaccuracy in the
setting out of the bolts. Horse-shoe-shaped packing
pieces of several thicknes ses were required to cope
with such problems. Location of brackets to make a
temporary support while the crane was holding the
pane 1 in position was not easy.
The amended fi xi ngs used in the final erection of alI
the panels, illustrated in Figure 4, retained the stud
fixing built in to the horizontal mortar joint Df the
brickwork, but used vertical unistruts with a captive
nut, built into the two brickwork columns . Vertical
slots in the steel columns gave tolerance on fixing.
The new angle cleats with horizontal slots gave alI
the degrees of movement necessary, and eliminated the
need for packing pieces, in addition to being easier
to fix.
Theffifi xings illustrate one satisfac tory solution to
the problem, but alternative systems could usefully be
considered for the future.
(5)
(2)
Lifting
Use of canvas slings was unsatisfactory. Chamfered
bricks along ths bottom of the panel meant that it did
not hang vertically, and 50 was difficult to handle
and align. Further examination showed this problem
could be overcome by careful positioning of the slings,
but this remains an unnecessary complication.
Slings were difficult to remove when the panel was in
position, and could be a cause Df damage to the D.P.C.
In the particular exercise described, slings were unavoidable, but thsrs are several other ways in which
panels could be lifted. For example, where the brick
contains largs psrforations, a lifting hook and continuous rod can bs grouted in. Alternatively two perpend' joints could be omitted towards the ends of each
panel, say three courses from the base, and a metal
plate pushed through the perpends, to which suitable
wire bonds could be attached.
(3)
Panel Support and positioning
Although no major problems were encountered in supporting the panel on initial release of the crane, it
is considered some temporary support such as push -pull
props, should be a vailable.
Positioning on the concrete to achi e ve the required
cavity width was found to be e~sier if temporary spacing pieces, ass e ss e d by ca reful mea s urement at the
base of each panel, were positioned at the bac k of the
D. P.C . against the concrete upstand. A similar vertical member between panels enabled the appropriate
joint thickness to be achieved.
(6)
No problems were encountered when incorporating reinforcemsnt and fixings.
Fixings
Jointing
A number of jointing materiaIs were examined. Those
requiring compression to be exerted during pane 1 positioning to achieve a seal were unsatisfactory since
insuffici e nt horizontal movement of panels was possible at this stage. For thi~ reason, use of a cellular neoprene material sleeved with a waterproof selfadhesive composition proved unsatisfactory, as also
was a wax-resin i mpregnated e xpanded polyurethane
foam. A pre-compressed bitumen impregnated foamed
polyurethane strip proved the most suitable of those
examined.
Modification of the special edge bricks on the panels,
to gi ve a wider bearing area in th e j oints, would be
an advantage. In addition this would increase stability of the panels during handling, without affecting the.aesthetic appearance of the joint.
Examination of other alternati ve materiaIs 1s however
necessary to extend the range of suitable sealants .
5.
FURTHER WORK
Mortar bed and D.P.C.
It is important that the panels squeeze out the mortar
bed to give adequate, even bearing. To ensure this,
the bsd should be laid immediately prior to positioning the panel. When the small panels were removed
after an initial trial, the bearing achieved was found
to be satisfactory by this method.
The D.P.C. - must be lapped, and should not extend
It has been estab lished that panels of the type described can be made and erected sat is factorily, to
give an efficient and pleasing cladd i ng. It is now
necessary to plan the next stage of the development
work. The observations made in 4.2 (4), (5) and (6)
point to the need for further consideration of the jig
design, method of fixing and jointing material. At
the same time , a prototype s tructure should be design e d
to test more conditions a nd to give a greater area of
~
panel for the research team to assess. It is essential that such a prototype should be built as a nor mal job, and not as apure development project, i . e .
a building contractor should perform his normal function Df erecting the frame and should only r eceive the
panels from the manufactu rers . One function Df the
prototype will be to establish a cost - time relationship for panel e r ection .
Concurrently with the bu ilding of the prototy pe a market research investigation is required, to establish
the potential market and to dete rmine whether any alterations to the design are necessa ry to suit the purchaser ' s needs . These can then be incorp orated into
a final design based on both expe rience from the manufacture and e rection Df the prototype, and the results
Df the market research .
The building i ndust ry, at present, is not sufficie ntly
buoyant to need a ma jor injection Df prefabricated
brick panels. The tests described above , together
with the p r ojected work, should enable a properly
tested and tried method Df manufacture and erection Df
prefabricated brick panels to be available for the
future upturn in building effort.
6.
BIBLIOGRAPHY
1.
Foster, O., "progress in Brickwork Pr efabricat ion a Compa rative Study " . Th e Brick Bulletin , VoI. 6,
No . 9, 1967 .
2.
Foster , O., Laird, R.T ., "Vertical Casting Df
Brick Panels" Trans . Brit . Ce ram . Soe . 67 (6) 22131 , 1968.
3.
Zenobi, G. V., Szerdahelyi, O. , "14-Storey buildings
in Switzerland with brick wall elements prefabricated by the Pr eton process : Designing Engineering and Const ructing with Masonry Products , Ed .
F. B. Johnson. Houston , Texas, Gulf Publishing ,
1969 pp . 460-67.
4.
Bryrup . J .• " P refab~icated Brick Facing Panels :
An I nte rnational Survey". S . I . B.M.A.C. Proceedings .
Ed . H. W. H. West, K. H. Speed , 1971 pp . 8- 14.
5.
Hamm , P . C., "The Oevelopment Df Prefabricated
Brick Panels in So uth Africa ", ibid . , pp . 15-22 .
6.
Anon . , "Prefabricated Brickwo r k. An outl1ne Df
International Oevelopments ", Brick Oevelopment
Association , London. 1972.
7.
Erdmann, M. P .• et.al . , "The Philadelphia National
Bank - A case study in Prefab r icated High Strength
Masonry ". Ziegel Oocumentation 3rd International
Brick Mason ry Conference Essen 1973; Bonn, Bandesverband der Oeutschen Ziegelindustrie. 1975 , pp .
13-17.
8.
Wa l t , H. • "T he Preton System: Prefab r icated Construction with Masonry Brick ", ibid . . pp . 594-96 .
9.
Finizi , S .• "Automatic Plant for Pre f abricating
Brick Wall Units ", ibid ., pp . 597-99 .
ACKNOWLEOGEMENTS
The authors acknowledge with thanks the assistance
given in this work by Mr. M. Simons , R. I .B . A. of Triad
Architects and Planners , Mr.E . Papper, Red l and Te chnology Ltd . , and Mr . P . Vallis , Red l and Br icks Lt d.
. b . 1-3
1. b. 1-4
storey height panel
bric kwork rem
. torcement
column
brickwork remtorcement
2600",
1
Fig. l
Arrangem ent af p a nels
column
,[2
l a) S
vertical ed
.
pecl al
ge unlt
uni t ~
(b) Junct lons;
·
o t panels;
Fig. 2
1.b . 1-5
pa ne l
col um n
pane l
Ihreaded sl ud fix in';j
built into bric kwor k
Fi g 3
Typica l f i x ing brac ke t Isubsequen tl y modi fied )
column
channe l inser i
fig 4
Mod i fi ed f ixi ng brack et