Note: Descriptions are shown in the official language in which they were submitted.
COMPOSITE BU~DING PANEL
Field Of The I~v~ ti()ll
The invention relates to a composite building panel and to methods
for the manufacLure of the panel. In particular, the inventioll is concerned with a
composite panel comprising a supporting layer of insulating material which is
adhered to a surface layer of cementitious material in a compression moulding
process. An open weave scrim-cloth-type material is encapsulated into the surface
layer to, amongst other things, minimi7e the possibility of breakage of the panel and
to introduce dimensional stability. The moulding process is used to impart a texture
10 and appearance to the surface layer which can be made to replicate the texture and
appearance of conventional surfacing materials.
Bacl~ ou~ Of The Il~vt;~
Stone has been employed as an exterior cladding, i.e. surfacing
material, in the building and construction industry for hundreds of years. Today,
the cost of natural stone construction tends to limit its application to that srnall
portion of the market that can afford such a luxury. Brick and other siding
materials have, for the most~part, been used as substitutes due to their relatively
low cost compared to naeural stone. There is, however, a need for high quality
sur~acing materials which exhibit all the authenticity of conventional surfacing
20 materials, i.e. texture, appearance and durability, but without the cost or application
problems associated with natural stone or ex3sting substitutes.
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Prior Art
Prefabricated composite building panels comprising an insulating
material core and facing or surfacing materials are known and have been used in
the construction industry. Canadian Patent No. 865,354, issued March 9, 1971 to
Kenneth W. Pope, discloses a prefabricated building panel comprising a rigid layer
of plastics material in cellular form, facing elements which are bonded to one face
of the rigid layer in spaced-apart relation, and a granular material adhered to, and
imbedded in the plastic between the facing elements. The granular material is
generally used to produce a hard, skin-like surface between the facing elements
10 which, depending upon the type of granular material employed, may resemble
mortar. The facing elements generally comprise segments of conventional surfacing
materials such as brick and stone.
Canadian Patent No. 876,090, issued July 20, 1971 to Donald E.
Shirley et al. describes a composite building panel comprising a core of thermal
insulating material encapsulated by a hardened hydraulic cement having disposed
therein a fibrous synthetic material such as glass fibre. The method of production
of these panels lends itself to long cycle times which the patent mentions as being
24 hours to produce one panel from start to finish.
United States Patent No. 4,044,520, issued August 30, 1977 to Albert
20 G. Barrows, describes a composite building panel comprising a base of expanded
polystyrene to which is applied a polymer fortified concrete facing. An acrylic
binder with quartz crystals carried thereon is provided over the concrete facing to
enhance the appearance of the panel and to illlprove its resistance to impact.
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Canaclian Patent No. 1,254,762, issued May 30, 1989 to David L.
Roodvoets, describes ~ prefabricated cement-fo~m composite p~nel co~ isil~g an
insu]ating base of synthetic resinous foam and a layer of ]ight-weight cementitious
material bonded by a latex adhesive thereto. The cementitious layer is constructed
of foam cement and a light-weight aggregate. This panel is particularly suited for
use ns a roofing panel.
SUMMARY OF THE lNVENTION
The present invention provides an innovative interior/exterior
surfacing alternative to brick or conventional siding materials, without the costs and
l0 application problems associated therewith. The invention represents an
pl~vement over prior art composite building panels in that the surface of the
panel can be made to replicate any conventional surfacing material, either natural
or man-made, in texture aml appearance while exceeding the insulative properties
thereo~ In addition, the panels are relatively light-weight, requiring less structure
to support the weight of the fac~ade as compared wi~h that for natural stone, and
they can be easily installed, even by inexperienced persons. Installation can be
achieved year round in all weather conditions employing readily available industrial
adhesives and fasteners. The panels can be cut by standard wood cutting tools such
as a carpenter's handsaw, a circular saw or sabre saw and can be conveniently
20 drille~l using standard high-speed drill bits. The method of manufacture of the
panels leads to fast production times and, therefore, a more cost-efficient panelg and
results in a panel of generally uni~orm weight regardless of the surface
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configuration. Various fininshing techniques allow the panels ~o be produced in a
variety of colours or tones, including multi-tonal colour variations.
Accordingly, there is provided in one aspect of the invention a
composite building panel which comprises a surface layer of cementitious material
to which is adhered a supporting layer of foamed insulating material in a
compression moulding proGess. An open weave scrim-cloth-type material is
embodied within the surface layer to minimi7e the possibility of breakage (increases
impact resistance) and to introduce dimensional stability to the panel. A mould is
used to impart a texture and appearance to the surface layer which recreates all the
10 authenticity of the original surfacing or siding material from which the mould was
produced. Although the surface ]ayer is moulded, the thickness of the surface layer
is maintained subst~nti llly consistent and at a predetermined minimum.
According to a second aspect of the invention, there is provided a
method of making a composiLè building panel co~ g the steps of:
a) dispensing a slurry of cementitious material in a mould;
b) placing a scrim-cloth-type material atop the slurry in the moukl;
c) colllpres~il.g the slurry to a predetermined thickness;
d) curing the compressed slurry to ~orm a shell;
e) injecting a foamable insu]ating material into the shell; and
f) euring the foamable insulating material.
The density and rigidity of the foamed supporting layer may be
increased significantly if, immediatély after the foamable insulating material is
injected into the shell, the mould is capped and placed in a press for a
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predeterrnined amounl of time, thus l;miting the extent to which the foam expancls.
The thickness of the surface layer may be maintained substantially
consistent and at a predetermined minimum by providing an inner moukl which is
use(l to compress the slurry in the mould. The moulding surface of the inner mould
resembles the moulding surface of the main mould, but provides areas of wider or
narrower definition to maintain the thickness of the surface.
The curing of the slurry is an exothermic process wherein heat is
generated during hydration and any excessive moisture is dissipated fram the mass.
Direct heat cannot be used to force-cure the slurry as the outer surface thereof
1() would cure before excessive moisture in the interior could be dissipated which would
lend to cracking as the moisture tries to escape. In order to accelerate the
hardening process, it is possible to employ infrared thermoreactor-type curing
tunnels. The nature of these ~unnels is such that they do not cure or dry the slurry
by means of direct heat but rather they aid in the dissipation of ~cessiv~ moisture
by maintaining a very dry (low relative humidity) atmosphere in the tunnel. The
use of such tunnels dramatically reduces the curing time for the surface layer and,
thus, significantly decreases the overall production time for the panels. Because no
t;~ccssive heat is generated in the thermoreactor tunnels, the hardened surface layer
shells can be handled immediately upon removal from the tunnel arld problems
~0 associated with thermal expansion in the forrnation of laminar materials are avoided.
In an alternate method of making the composite building panel, the
supporting layer of foamed insulating material may be pre-formed and used, instead
of the inner mould, to con~ ess the slurry. Infrared thermoreactor-type tunnels
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may then be advantageously employed in curing the compressed slurry, without
melting or burning the supporting layer of foarned insulating material.
Typically, a 4' x 4' x 2" panel producecl in accordance with the
invention and having a surface layer thickness of a~plu~hllately 3/8" exhibits an over-
all weight of about 80 Ibs or about S ]bs/ft2, and can be produced in a~ o.~ lately
30 minutes when infrared thermoreactor-type tunnels are used in the curing process.
The panel has zero surface flame spread, is impervious to moisture, and resists the
freeze-thaw cycle which is destructive to many construction materials.
Further features and advantages will be described hereinbelow in
10 conjunction with the accompanying drawings.
BRIEF DESCRlPTION OF THE DI~W~N(;S
Fig. 1 is a plan view of a composite building panel in accordance with
the preferred ernbodiment of the invention.
Fig. 2 is a cross-sectional view of the panel along line 2-2 in Fig. 1.
Figs. 3 to 6 are cross-sectional views, showing only those features at
the plane of cross-section, of dirrerelll stages in the mould making procedure.
Figs. 7 and 8 are cross-sectional views of the surface layer shell being
made in accordance with the method of the invention.
Fig. 9 is an oblique view in section of a typical surface layer shell
20 made in accordance with one method of the invention.
Fig. 10 is an oblique view in section alld partially broken away
showing the panel made in accordance with the invention.
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Figs. 11 and 12 are cross-sectional views of the panel being made in
accordance with the alternate metllod of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODlMENT
Figs. 1 and 2 illustrate a composite building panel 10 in accordance
with the preferred embodiment of the invention. The panel 10 has a moulded
surface 12, which can be made to replicate any textured design whether natural or
man made, but is shown in the drawings as simulating a natural stone construction.
The surface 12 of the panel 10 has raised portions 14 which correspond to the
;ndividual stones of such a construction and which are separated by depressions 16
10 corresponding to the areas which the mortar occupies to mailltain the stones in
position.
~ s shown in Fig. 2, the panel 1û colllplises a moulded surface layer
18 of cementitious material and a supporting layer 20 of foamed insulating material.
The surface layer 18 preferably covers one surface and all four edges of the
supporting layer 20. The cementitious material used for the surface layer 18 is
preferably a fast-setting portland/gypsum cement blend such as DURACAL (trade-
mark), for exterior use, and HYDROCAL (trade-mark), for interior use. The
supporting layer 20 of foamed insulating material is preferab]y a polymeric
isocyanate based polyurethane foam which is water- or CO2-blown, and not freon-
20 blown, in order to conform to building codes. Water-blown polyurethane foam has
an added advantage in that it does not support a flame and, thereby, provides for
a safer product.
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An open we~ve scrim-cloth-type material 22 of jute, sisal,
polypropylene, ~olyethylene or the like, and preferably having woven openings of
approximately l/~, is en~apsulated into the surface layer 18 to ",i~,i",;~t~ the
possibility of breaking and to introduce dimensional stability to the panel. In
addition, webs 24 may be provided to increase the overall strength and rigidity of
the panel.
The thickness t of the surface layer 1~ is maintained substantially
consistent and at a predetermined n~ illlulll value, even at the depressions 16, as
most building codes require a minimum thickness of flame-resistant material for
10 shielding insulating materials. By making the surface layer 18 consistently thick,
substantial weight and material savings can be realized as compared with a panel
having a surface layer of a depth d in order to maintain the required Illinilllu
thickness at the depression 16.
The panels may be produced in various configurations depending
upon the type of surfacing material being simulated, i.e. natural stone, brick,
flagstone, wood, etc. For instance, it rnay or may not be desirable to have surface
patterns which repeat from panel to panel or to have rectilinear panel edges. In
the panel 10 shown in Fig. 1, the pattern of the rnoulded surface 12 is random,
simulating a natura.l stone construction. The configuration of the sides 26 is such
20 that the panels 10 may be nested or interlocked with panels having mating sides but
having a different moulded surface pattern to eliminate excessive pattern repetition.
Where pattern repetition is not of concern, a single modular panel may be
produced with four mating sides wherein the sides may be rectilinear, interlocl~ing
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or a combination of both.
According to the type of panel to be produced, model panels of the
genuine material are laid out by skilled professionals, duplicating actual construction
and me~hods. In the case of the panel 10 shown ;n the drawings, the model panels
are laid out using real stone and mortar as would be prepared by a mason. Any
one of several techniques such as sand casting, silicone casting or aluminum casting
may be used to produce moulds of the model panels, however7 silicone casting is
preferred for ease of release of the mould from the original and of the panel from
the rnould, and for its ability to capture and duplicate the finest of details.
1() A simplified cross section o~ the resulting mould 30 is shown in Fig.
3. The moukling surface 32 complements precisely the surface of the original
model. To create the irlner mould 54 (see Fig. 6), which will be used in the
moulding process to maintain the thickness of the surface layer 18 consistent, a
complementary "panel" 34 is produced (see Fig. 4) using a similar casting procedure
and is removed from the main mould 30. The panel 34 is an exact replica of the
original model having corresyonding stone-resembling regions 36 and mortar areas
38 (see Fig. 5). The panel is relieved at lines 40 to create wider definition for the
mortar areas 38 and the sides are cut at 42, in order to provide for the
predetermined minimum thickness of the surface layer 18. If strengthening webs
24 are to be provided, the panel 34 is cut at 44 into a plurality of sections 48 and
trimmed at 46, preferably with a slight taper. The sections 48 are mounted to a
support means 50 which may comprise a p]anar backing or a plurality o~ support
members. The support means extends outwardly at least to the outer edge of the
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main mould 30 and is employed to maintain the sections 48 in proper position
rel~tive to the moulding surface 32, thu~ providing a consistently wide mould cavity
52 ~see Fig. 6).
Referring now to Fig. 7, a s]urry 56 of hydrous cement;tious material
is dispensed evenly in the main mould 30. An open weave scrim-cloth-type material
22 is cut to size and is positioned atop the sl-lrry 56 in the mould 30. The scrim-
cloth 22 is preferably cut larger than the moukl 30 in order to ensure that the
entire surface layer including the edges has a scrim-cloth component.
Using the sectioned inner moulcl 54, the slurry 56 is compacted (see
10 Fig. 8), forcing it to flow throughout the mould cavity 52 and through the woven
openings of the scrim-cloth 22 and into the recesses hetween the sections 48 to
form the webs 24. The slurry 56 is cured in this campressed state, preferably in
infrared thermoreactor-type tunnels, to form a hardened scrim-cloth-lined surface
layer shell 58 as shown in Fig. 9. Such tunnels may be advantageously employe~l
in the curing process with silicone rnoulds (from which more detailed panels can be
produced) without any deleterious effects thereto.
By placing the scrim-cloth 22 atop the slurry, the scrim-cloth 22 is
embedded in the surface layer to a sufficient depth to effect reinforcement thereof,
yet shallow enough to provide a roughened inner surface 60 to which the foamable
20 insulating material of the supporting layer 20 will more readily adhere. It will be
recognized that a smooth inner surface 60 of the surface layer 18 would increase
the possibility of del~min~tion of the surface and supporting layers, resulting in a
substantially weaker panel
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A foamable insulating material is injected into the shell 58 and is
cured to form the supporting layer 20 (see Fig. 10) ancl to complete the panel 10.
The density and rigidity of the supporting layer 20 and, thus, the overall strength
of the panel 10 may be increased significantly if, immediately afler the liquid plastic
is injected intQ the surface layer shell 58, the mould is capped and placed in a press
for a predetermined amount of time, limiting the extent to which the foam expands.
Preferably, a backing 62 of kraft paper or the like is applied prior to
the pressing step. The backing 62 absorbs any gasing generated during curing of
the foamed plastic thus elirnin~tin~ the possibility of voids forming in the supporting
layer 20. Advanta~eously, the backing 62 becomes saturated with resin from the
foam;ng plastics material becoming effectively a waterproof skin.
In an alternate methocl of making the composite building panel 10,
the supporting layer 20 of foamed insulating material may be in the form of a pre-
formec~ fs~amed insert 64 and used, instead of the inner mould 54, to compress the
slurry (see Fig. 11). In this method9 a secondary mould (not shown) is produced
in which the foamable insulating material may be formed. Preferably, the secondary
mould is made by vacuum-forming a surface shell of plastic on the inner mould 54,
thus allowing the foamed insert 64 to be formed with a surface configuration wbich
ensures the same consistent surface layer thickness as does the inner mould 54.
The foamed insert 64 is produced in a similar manner as described
above, i.e. by injecting a foamable insulating material into the vacuum-formed shell.
If desired, backing 62 is applied and the shell is capped and placed in a press to
limit the extent to which the foam expands, thus producing a more dense and rigid
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insert 64. As shown in Fig. 11, the foamed insert 64 comprises a p]urality of
foamed insert sections 68 corresponcling to the inner mould sections 48. The
sections 68 are temporarily mounted on support means 50 which maintain the
sections 68 in proper position relat;ve to ~he nnoulding surface 32 of the mould 30.
It has been found that a supporting layer 20 which has been
produced by injecting a foamable insulating material into the hardened scrim-cloth
lined shell 58 adheres better to the surface layer 18 than does a pre-formed
supporting layer inserted into a cementitious slurry which is then cured. A decrease
in adhesion between the supporting and surface layers increases the tendency of the
10 layers to delaminate. Therefore, in order to increase adherence and to provide
additional stability, the foamed sections 68 may be provided with through-ho]es 66
(either as part of their forming procedure or in a subsequent operation) which will
allow the cementitious slurry material to flow therethrough during compression.
Various other means or techniques to prevent delamination of the surface and
supporting layers may alternatively be employed.
To m~ke the panel in accordance with the alternate method of the
invention, a slurry 56 of cementitious material is dispensed into the main rnould 30
and a scrirn-cloth 22 is placed atop the slurry 56. A pre-formed foam insert 64 is
then used to compress the slurry 56 to a predetermined thickness (see Fig. 12) and
20 the slurry 56 is cured in this colllpresscd state, preferably in an infrared
thermoreactor-type tunnel. When the slurry 56 has hardened, the panel is removed
from the mould 30 and the foamed insert support means 50 are removed from the
panel.
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In addition to the various surfacing materials which can be emulated,
the building panels in accordance with the presen~ invention can be produced in a
variety of colours. The slurry 56 may be tinted using conventional mortar tinting
materials or elastomeric acrylic type materials, as well as some latex based
materials. The main rnould 30 itself can be pre-tinted prior to the dispensing of the
slurry by brush or other hand-wiped methods. Alternately, the product may he
produced as a single, base-colour panel having the toning or colourant applied as
a final operation over the entire surface or portions thereof. In either case, it is
possible to produce multi-coloured panels. However, the post-production colouring
10 metho~l is preferable in that it enables panels to be produced and warehoused
without finishing colourants, leaving the tinting as a separatc operation which can
be performed on an as needed basis and in accordance with a customer's particular
request.
Once the panel has been produced and, if desired, finished, the panel
preferably undergoes a surface water rinse to remove any collected foreign material.
The washing serves to eliminate streaking or bleeding which occurs as water is
dissipated during curing of the surface layer. Minerals contained in the water (or
dissolved therein from the cementitious material) are drawn with the water to the
surface where the water evaporates, leav;ng behind a residual layer of minerals.
20 This residual layer is susceptible to moisture and, therefore, is prone to the
destruc.tive freeze~thaw cycle. The water rinse removes this residual layer thus
rendering the surface layer impervious to moisture.
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The panels may be installed by app]ying a comnnercially a~ailable
adhesive to the back of the panel (or backing 62 if provided) and/or to the surface
to which the panel is to be applied and pressing the panel into place. For
additional support, the panel may be further secured by standard fasteners such as
screws. The panels can be cut by standard wood cutting tools such as a carpenter's
handsaw, a circular saw or sabre saw and can be conveniently drilled using standard
high-speed drill bits. A matching grouting material may be supplied along with the
panels for filling screw holes and joints where necessary.
Although the panel of the present invention has been shown and
10 desired as being relatively planar, it is not necessarily limited to such an
embodiment. For example, corner panels for both interior (90~) and exterior (270~)
corners may be produced in accordance with the methods described hereinabove.
Such panels would facilitate installation by eliminating the need to form joints at the
corners with planar panels, thus, adding to the realistic appearance of the entire
panel construction. The present invention may also be extended to produce other
constructive or decoratlve features such as lintels for above doorways, without
departing from the spirit and scope of the invention as defined in the appended
claims.
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