U.S. patent application number 10/239276 was filed with the patent office on 2005-03-24 for composite building components.
Invention is credited to Hoie, Tor, Swann, Peter J.
Application Number | 20050064145 10/239276 |
Document ID | / |
Family ID | 9888230 |
Filed Date | 2005-03-24 |
United States Patent
Application |
20050064145 |
Kind Code |
A1 |
Hoie, Tor ; et al. |
March 24, 2005 |
Composite building components
Abstract
A structural insulated panel having a core (40) of expanded
polystyrene sandwiched between, and bonded to, two facings (52).
The facings are attached to faces of the core formed by moulding.
Preferably the core is an expanded polymer moulding and the
preferred polymer is polystyrene. The panel is useful as a building
component.
Inventors: |
Hoie, Tor; (Themes Ditton,
GB) ; Swann, Peter J; (Walton on Thames, GB) |
Correspondence
Address: |
Thomas M. Galgano
Galgano & Burke
Suite 135
300 Rabro Drive
Hauppauge
NY
11788
US
|
Family ID: |
9888230 |
Appl. No.: |
10/239276 |
Filed: |
May 26, 2004 |
PCT Filed: |
March 22, 2001 |
PCT NO: |
PCT/GB01/01272 |
Current U.S.
Class: |
428/167 |
Current CPC
Class: |
Y10T 428/2457 20150115;
E04C 3/29 20130101; E04B 7/22 20130101; E04C 2/296 20130101; E04C
2/521 20130101 |
Class at
Publication: |
428/167 |
International
Class: |
B32B 003/28 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 22, 2000 |
GB |
0007000.3 |
Claims
1. A structural insulated panel having a core of expanded
polystyrene sandwiched between, and bonded to, two facings, the
facings being attached to faces of the core formed by moulding.
2. A panel as claimed in claim 1 wherein the core is an expanded
polystyrene moulding.
3. A panel as claimed in claim 2 wherein the core is formed by
expansion of polystyrene cells in a mould in such that any
variations in density are minimal.
4. A panel as claimed in any preceding claim wherein the expanded
polystyrene is produced by pre-expanding polystyrene, maturing the
pre-expanded polystyrene and then expanding the pre-expanded
polystyrene and then expanding the pre-expanded matured polystyrene
in steam.
5. A panel as claimed in any preceding claim wherein the panel
dimensions are 1.2 metres wide, 0.2 metres thick and 2.4 metres
high/long.
6. A panel as claimed in any preceding claim wherein the facings
are made from cementitious board, plywood, gypsum/textile composite
board or OGB.
7. A panel as claimed in any preceding claim wherein the core
comprises two mirror image halves.
8. A panel as claimed in claim 7 wherein each mirror image half of
the core is provided with male/female location means for engagement
of the two halves.
9. A panel as claimed in any preceding claim wherein the core
includes at least one passageway.
10. A panel as claimed in claim 9 wherein there is a matrix of
passageways positioned such that each passageway will align with,
and be capable of connection to, a passageway of an adjacent such
panel.
11. A panel as claimed in any preceding claim wherein an organic
non-solvent, moisture controlled penetrative adhesive or glue is
employed for bonding the parts of the panel together.
12. A panel as claimed in any preceding claim including recesses
along the edges of oppositely facing surfaces of the core for
receiving joining elements for connecting the panel to another such
panel.
13. Use of an individual moulding of expanded polystyrene as a core
in a structural insulated panel in which the core is sandwiched
between, and bonded to, two facings.
14. A method of manufacturing a structural insulated panel
comprising forming an expanded polystyrene core with at least two
opposite faces produced by moulding and bonding facings to the two
moulded faces.
15. A method as claimed in any preceding claim wherein the step of
forming an expanded polystyrene core comprises pre-expanding
polystyrene beads by heating the beads and providing steam thereto,
cooling and drying the pre-expanded beads, maturing the
pre-expanded beads and then further expanding the pre-expanded and
matured beads with steam in a mould.
16. A method as claimed in claim 15 wherein the mould used for
further expansion of the pre-expanded and matured beads comprises a
two part mould defining a mould cavity, each part being connected
to a steam source, wherein the surfaces of the mould cavity are
provided with a multiplicity of steam injection points.
17. A method as claimed in either claim 15 or claim 16 wherein the
mould is an hermaphrodite mould.
18. A method as claimed in claim 17 wherein the mould is shaped to
provide each half of the core with male/female location means.
19. A method as claimed in any one of claims 15 to 18 wherein the
mould is shaped to form recesses along the edges of oppositely
facing surfaces of the core.
20. A method as claimed in any one of claims 15 to 19 wherein the
mould is shaped to form at least one passageway in the core.
21. A method as claimed in any one of claims 14 to 20 wherein the
bonding of parts of the panel is carried out with an organic
non-solvent, moisture controlled penetrative adhesive or glue.
22. A method of constructing a building comprising using a panel as
claimed in any one of claims 1 to 12.
Description
[0001] This invention relates to composite building components,
primarily but not exclusively for use in the construction of
buildings such as houses and more particularly to composite
building components which are generically known as structural
insulated panels or SIPs.
[0002] Typically, SIPs incorporate a relatively flat plastics foam
core of rectangular shape sandwiched between, and bonded to, two
relatively thin, high strength, rectangularly shaped facings to
form a laminated sandwich SIPs have been in use for many years and
have become well established in the construction industry,
particularly in the USA, as an alternative to traditional
brick/block cavity walls and the framed panel inner skin and outer
skin brick/block cavity walls of timber frame buildings.
[0003] The foam cores of SIPs provide thermal and acoustic
insulation which are superior to those of conventional brick or
timber built houses, are resistant to moisture, shock, impact and
fire and avoid the need for a water vapour barrier (house wrap).
Moreover, SIPs are lightweight and easy to manipulate and a single
SIP takes the place of many masonry blocks or building bricks,
thereby decreasing construction time and reducing material costs.
The foam cores also permit passageways or conduits for supply lines
such as electrical wires to be cut in the fully formed foam cores
in the factory, prior to assembly of the SIPs on site which further
decreases construction time.
[0004] Instead of being applied separately in a second stage, it is
advantageous to manufacture walls, floors and roofs incorporating
insulation material as part of the building (or individual module
structure).
[0005] Such modules or panels known as SIPs have been used in the
United States for over 50 years. These SIPs vary in thickness from
say 50 mm up to 300 mm and to comply with common international
building component dimensions, a typical wall or floor SIP would be
2.4 metres.times.1.2 metres and the thickness would depend on the
particular application, load bearing qualities and thermal
insulation requirements.
[0006] In the USA, the most popular SIPs comprise an expanded
polystyrene (EPS) core faced on its inner and outer surfaces
respectively with two facing sheets of say 9 mm to 15 mm thick of
OSB (oriented Strand Board) or ply wood or in some cases
cementitious board. These SIP building components have been
successfully used, extensively over the last 50 years in the US in
the construction of houses (usually single storey). Typically, the
SIPs were supported from a base length of timber fixed to a
suitable foundation and joined by timber splines or so called
biscuits to each other to form the walls of the building. When
larger roof and wall loadings were required, the SIP modules were
reinforced by incorporating a 2.times.4 inch timber reinforcing
post within the SIP or in some cases these timber elements were
used to connect the individual SIPs to each other. This method
results in a SIP wall reinforced with timber frame elements.
[0007] Timber frame elements suffer from dry rot due to poor
circulation of fresh air around the timber elements. The use of
timber elements can also give rise to "cold spots" which reduce
thermal efficiency. Therefore with any SIP for use with timber
frame elements there is a need for adequate air circulation around
the timber elements.
[0008] It has been ascertained that an SIP foam core has several
important functions. The core has to be stiff enough to keep the
distance between the facings constant and must also be so rigid in
sheer that the facings do not slide over each other and to prevent
buckling. If the core is weak in sheer, the facings do not
co-operate and the SIP sandwich will lose its stiffness. It has
also been ascertained that the foam core has to fulfil further
complex demands, namely strength in different directions and low
density (economics) and also has other special demands with regard
to buckling, insulation, moisture absorption, ageing, resistance
etc. For example, the facings are required to transmit the
compressive loads down to the foundation and the adhesive used to
bond the facings to the core must be sufficiently strong to resist
sheer and transmit load between the core and the facings.
[0009] The most practical and economical solution initially found
to manufacture an SIP giving the requisite load bearing strength
and insulation qualities, was an SIP panel utilising a core of high
density (HD) extruded polystyrene (XPS). Testing XPS proved that
this material had the necessary qualities and the synergy required
to construct an SIP panel capable of sustaining compressive loading
as would be found in a typical three storey housing structure.
Testing was carried out at the Building Research Establishment
(BRE) and it was proven that these XPS cored SIPs faced with ply
wood facings were capable of sustaining phenomenal loads.
[0010] However, further investigation showed that the initial
advantages of XPS were overweighed by XPS being considerably more
expensive, both in terms of manufacturing and capital expense which
rendered XPS uneconomical to use in an SIP composite building
component.
[0011] Further consideration was therefore made of the SIP products
as manufactured and used in the USA, particularly because SIPs
utilising cut EPS cores have obtained approvals (ASTM) in the USA
and general acceptance for use as load bearing building panels in
construction. The loading figures achievable for EPS core material
in use in the USA for SIPs are common knowledge. The minimum SIP
core thickness typically used for SIPS in the USA is 150 mm whereas
in Europe cores of 50 mm thickness could be described as
commonplace.
[0012] Cut EPS is typically in the region of three times less
expensive than XPS and moulded polyurethane foam which is also used
as a core in a SIP system already on the UK market. Urethane cores
are dangerous in that they give off poisonous fumes when burned and
so were not considered.
[0013] Also, plans are afoot globally to ban the use of urethane in
composite building components because urethane used in buildings,
particularly houses, is no longer considered to be an
environmentally responsible material.
[0014] The beauty of using cut EPS for the core material of SIPs is
that EPS is not only cheap to manufacture but is universally
regarded as an environmentally responsible construction material.
This is because EPS does not contain harmful fibres, represents an
efficient use of natural resources which saves energy and conserves
resources through its manufacture, use and disposal. EPS does not
contain or release compounds harmful to the ozone layer such as
CFCs or HCFC's and its manufacture and use represents no danger to
health. EPS insulation, in particular, has an invaluable role to
play in helping to achieve dramatic reductions in energy use and
reducing emissions that contribute to the greenhouse effect EPS can
be, and is being, recycled and the EPS industry is also leading the
way in terms of developing a range of waste management solutions to
ensure maximum recovery of waste. Further, EPS manufacture by the
well known three stage process comprising pre-expansion, maturing
and final block moulding is already proven and is capable of
economically producing gigantic blocks of EPS of up to 20 metres
long, 6 metres wide and 4 metres thick which is then cut into
smaller sizes by the standard hot wire technique depending upon
their intended purpose, such as cores for SIPs.
[0015] The raw material from which EPS is made is in the form of
free flowing, lightweight and cellular beads made from styrene
monomers derived from ethylene and benzene, themselves derived from
crude oil. The beads contain an expansion agent, usually pentane,
and have the appearance of granulated sugar. The raw material,
which is available in various grades and can be described generally
as regular and fire retardent types, is delivered in this form to
the manufacturing plant in either 600 or 1000 kg `octabins` or in a
bulk carrier for transfer to storage silos, the latter being more
economical.
[0016] In the first, pre-expansion, stage, the polystyrene beads
are pre-expanded to 20-40 times their original volume by heating to
a temperature of about 1000.degree. C., using steam as the heat
carrier, in an enclosed vessel known as a pre-expander. In
pre-expansion, the volume of the polystyrene beads is increased and
their bulk density changes accordingly--e.g. from 620 kg/cu. metre
to 20 kg/cu. metre if the moulded density of the foamed material is
to be 20 kg/cu. metre.
[0017] Following pre-expansion, the beads are cooled and dried
before being stored to mature. After pre-expansion the beads have a
partial vacuum and this is equalised by allowing air to diffuse
through the beads. The beads are matured over around 24 hours. The
density of the foamed block moulding produced from the beads is
therefore practically the same because in final forming the block
mould is completely filled with beads.
[0018] This second stage of maturing is required because, after
cooling, the pre-expanded beads are initially still sensitive to
pressure, and time must be allowed for them to acquire adequate
strength. This happens by diffusion of air into the foam cells
until the reduced pressure resulting from cooling and expanding
agent condensation has been compensated. Accordingly, the
pre-expanded beads are generally dropped straight out of the
expander into a fluidised bed drier in which warm air from
25.degree. to 35.degree. C. is blown in through the base of the
drier. Fluidised bed driers operate continuously but must be
designed with sufficient length to ensure adequate drying. The
residence time of the expanded beads in the fluidised bed should be
1 to 5 minutes depending on their moisture content. After drying,
the freshly pre-expanded beads are transferred to a maturing silo.
Whilst maturing some expanding agent (pentane) escapes and this
cuts down the foam pressure decay time required in moulding.
[0019] In the third and final block moulding/secondary expansion
stage, the pre-expanded and matured beads are further expanded with
steam in the mould until they fuse together to form a moulded
block. Although polystyrene can also be expanded with other heat
sources, e.g. with boiling water, hot air and other gases, steam
has decisive advantages because:--it is a highly efficient heat
transfer medium; its temperature at atmospheric pressure is close
to the softening point of polystyrene; it is readily available; and
it helps in the actual expansion process. Polystyrene is highly
permeable to steam (water vapour) and as soon as the expanding
agent starts to expand the beads, steam permeates into the newly
formed cells. The steam pressure inside the cells thus balances the
pressure of the steam surrounding the beads which can expand
against virtually no resisting force. This permits expansion of the
beads to low densities.
[0020] The mould for the production of block polystyrene foam for
use in producing SIP cores normally consists of two parts defining
a mould cavity that produces the shape of the finished moulding
with each mould part being bolted onto a steam chamber. Steam is
introduced into the mould cavity through a multiplicity of special
core vents or jets, usually made from aluminium alloy. The spacing
and number of core vents and the total vent area is important to
guarantee proper filling (with no back pressure), steaming,
cooling, and consequently the quality of the mouldings. Ease of
cleaning and maintenance of the core vents is an important feature
for efficient operation.
[0021] The mould parts typically are closed using hydraulic
pressure and the pre-expanded beads are blown into the closed mould
using air injectors with the air escaping via the steam nozzles or
special vents. For large block moulds, for producing gigantic EPS
blocks, which are of simple design, steam is supplied via the steam
chambers through the multiplicity of steam jets or vents in the
mould walls. The block mould is completely filled with the matured
pre-expanded beads which are, in effect closed polystyrene cells,
and then steamed. As a result of the renewed heating to
temperatures between 110.degree. and 120.degree. C., further
expansion of the beads takes place but is confined to filling up
the free volume of the mould cavity which compresses beads together
because being contained by the mould they cannot expand freely and
therefore creates internal pressure in the mould cavity. The beads
fuse together along their boundary faces to form a moulded block.
After a cooling (pressure reduction) period, usually using a vacuum
to remove any moisture, the moulded block is dimensionally stable
and can be released from the mould. Any remaining expanding agent
(pentane gas) is expended during moulding so that the moulded block
does not contain any residual expanding agent.
[0022] Investigations were carried out into American production
methods for SIPs using EPS for the core material and the quality
control procedure, and the material consistency was found to be
seriously lacking and would not comply with typical current British
& European quality control assurance schemes (BS5750, ESO 9000
and 9002).
[0023] Detailed testing of the lamination of SIPS using EPS faced
with OSB, ply wood and cementitious board were carried out. It was
found, however, that spasmodically the SIP panel would be prone to
collapse in the process of manufacture, usually when the panels
were placed in vacuum press for curing of the adhesive. Detailed
examination of the EPS core materials showed that whilst this
material was manufactured to BS 3837/BS4370 and BS4735 and the
overall density of say a 2.4.times.12.times.20 cm panel showed the
material was correct, if the panel was cut into segments however
there was seen to be significant variations in density across the
panel.
[0024] Panel samples were purchased from numerous UK EPS block
manufacturers and sample weight tests showed significant variation
in density from panel to panel and also segment tests showed
significant density variations across individual panels. It was
realised that with such density variations and poor quality control
methods, EPS manufactured and as supplied in the UK market would be
totally unsuitable for the manufacture of SIPs for use in housing.
There was therefore a need to devise some new form of manufacturing
process for the cores of SIPs that enabled the density of the
finished product to be controlled so that it could be held within
exacting standards.
[0025] Another disadvantage of cores cut from EPS blocks, is that
judder which occurs during hot wire cutting of the EPS block causes
the formation of ridges and indentations in the surfaces of the cut
EPS cores. In order to provide the precise surface tolerances
required for the core surfaces that are bonded to the facings, the
cut cores are passed through a planar thicknesser. This process
produces waste EPS, another disadvantage.
[0026] It is known that when cycle crash helmets are moulded as
individual items it is possible to control the density and quality
within defined limits and apply stringent quality controls, thus
ensuring that this vital piece of head protection will meet the
necessary British Standards tests.
[0027] The present invention involves using moulding to manufacture
expanded polymer cores for SIPs as individual quality controlled
items. It has been found feasible to apply quality control
procedures to produce a moulded expanded polymer product capable of
complying with the exacting criteria of the insulating core
material of a SIP. Specifically, it has been found possible by
moulding polymers in a quality controlled environment to ensure
that density variations do not exceed permitted amounts.
[0028] In one aspect, the present invention resides in a structural
insulated panel having a core of an expanded polystyrene moulding
sandwiched between, and bonded to, two facings, facings being
attached to faces of the core formed by moulding.
[0029] The core is preferably formed by expansion of polystyrene
cells in a mould such that any variations in density are minimal
and/or the core is of sufficiently uniform density to permit load
bearing of the panel without the need for additional structural
supporting elements.
[0030] Moulded cores of expanded polystyrene have been made that
exhibit a density variation of as low as up to/down to .+-.2.0% as
compared with the large density variations in cores cut from
gigantic blocks.
[0031] Moulded cores in accordance with the invention are
calculated to be 40% stronger than has hitherto been possible and
have improved u-values.
[0032] In a still further aspect the invention resides in an
individual moulding of expanded polymer for use as a core in a
structural insulated panel in which the core is sandwiched between,
and bonded to, two facings.
[0033] The invention also resides in methods of manufacturing any
of the structural insulated panels defined above.
[0034] Hereinafter the expanded polymer will be referred to as
XPS.
[0035] Significant advantages result from the invention. Firstly,
the use of additional structural members of timber etc., in
particular beyond the bottom story is avoided and thermal bridging
within a building made form such laminated composite building
components is minimised, thereby raising thermal efficiency. The
structural insulated composite building components rely on the
compression strength (core strength) of the component without the
use of timber.
[0036] A building can be produced, in particular a house, in which
not only the traditional cavity wall and brick construction are
replaced but also joist and floorboard floors and timber trussed
roofing systems are replaced. This is all for a fraction of the
cost of these traditional systems. There are therefore significant
technical advantages over other competing products, notably
urethane cored composite building component structures, timber
frame, and some concrete or steel framed structures.
[0037] Building costs are reduced and construction is facilitated
by means of a preferred embodiment of the invention in which the
basic moulded core structural insulated panel is 1.2 metres (1200
mm) wide, 0.2 metres (200 mm) thick and 2.4 metres (2400 mm)
high/long and 2.88 square metres in area. It has been calculated
that it takes 334 standard bricks to produce a normal cavity wall
construction (one brick thick and two half brick skins) of the same
area. This is clearly a major leap forward in terms of on-site
productivity.
[0038] To aid in flexibility of building, there is also envisaged
blocks that are 0.6 metres and 0.3 metres wide, 2.75 and 3 metres
high (3 meters is storey high) and 50 mm, 75 mm, 150 mm, 250 mm and
300 mm thick.
[0039] The reinforcing facings need to be tough and to this end,
facings of cementitious board, plywood, gypsum/textile composite
board or OSB (oriental strand board) are preferred.
[0040] In order to ensure that the steam carries to all parts of
the mould and ensure minimum variations in density, all surfaces of
the mould are provided with a multiplicity, e.g. thousands, of
small steam injection points.
[0041] By providing all surfaces of the mould with a multiplicity
of small steam injection points, the moulded core structural
insulated panel of the invention is strong, free of noxious gases,
and thus is suitable for its main purpose as an environmentally
responsible low cost structural building component.
[0042] Preferably, each moulded core is individually moulded in a
full sized mould which provides a stronger core than that cut from
a block. This is because the core has an integral surrounding skin
of well-fused, denser cells.
[0043] In a preferred embodiment, which facilitates moulding and
the obtaining of full thickness dimensions (at least 200 mm), as
well as having other advantages, the core is made in two mirror
image halves that are moulded in what is called an hermaphrodite
mould so that two mould halves taken from the same mould can be
bonded together to complete a two piece core.
[0044] Each mirror image half is provided with male/female location
means, preferably in the form of complementary projections and
recesses with each half being provided with both complimentary
projections and recesses so that it is a simple matter to turn one
half through 180.degree. and engage the projections and recesses of
one half with the complimentary recesses and projections of the
other half.
[0045] A given strength can thus be obtained with individually
moulded cores at a lower density than with cut blocks. This saving
is estimated at approximately 10% for densities of 25 kg/cu.mtr.
and higher. Accordingly individually moulded cores exhibit a lower
density gradient than large cut blocks, especially at higher
densities that always show considerable gradation in density across
the thickness.
[0046] The certre of a gigantic moulded block is of significantly
lower density than the overall density. It is, therefore, necessary
to mould blocks at a higher density than is actually required in
order to make sure that the centres of the blocks reach the
required density. This problem does not occur with moulded cores
and this factor gives a further saving of 8% to 10%. Since no
density gradient is present, the moulded core weight and hence the
product quality, are more consistent.
[0047] In order substantially to facilitate the supply of services
in a building utilising moulded core structural insulated panels,
preferably, the mould is provided with inserts which form hidden
passageways or conduits in the ultimate moulded core which are
suitable for accommodating any form of supply line but in
particular electrical wires and cables. In addition to electricity,
conduits may be provided for gas, communications, water,
ventilation and other usages. A matrix of passageways can be formed
in this way to satisfy all necessary service requirements which are
aligned as between adjacent panels both side by side and one above
the other. Moreover, the positions of the matrix of passageways in
relation to the dimensions of the core, can be so arranged that
when one panel turned onto one of its sides of lesser width to form
the wall beneath a window for example, the passageways in the
adjacent panels will still be in alignment.
[0048] Whilst a cut core would loose some of its strength by the
removal of material for supply passageways, e.g. 0.1% this does not
happen with two part moulded cores because the passageways will be
lined with a skin of fused cells that is integral with the
surrounding skin of fused cells.
[0049] It has been found that an organic non-solvent, moisture
controlled penetrative adhesive or glue e.g. MCPU, is the most
effective, not only for bonding the facings together, but also the
two part core pieces when the core is moulded in two parts. Such an
adhesive is stronger than the building component itself because it
penetrates between the closed cells. With two piece cores, the
penetration of the adhesive in this way forms a layer of adhesive
which extends between the cells of each moulded piece, thereby
preventing the formation of a plane of separation between the two
pieces and forming a bond that lasts as long as the foam cores.
[0050] It has been ascertained that the moulded foam core and
reinforcing facings glued together is comparable with an I-beam but
is stronger than steel. The foam core is the equivalent of the
I-beam web and the facings are the equivalents of the I-beam
flanges.
[0051] Whilst the strength of the panel is more than sufficient for
normal building structures, because of its composite nature it is
possible to increase the strength still further by adding a layer
of, for example, a textile or fibre cloth to the interior surface
of one or both facings. Adding such a layer or layers may have
effects other than or in addition to increasing strength depending
on the properties of the material. As one example, fire retardant
properties may be increased. In another example, a textile layer
may have ceramics embedded in it for security reasons or a thin
electricity conducting wire entwined therein which could allow for
heat flow and so obviate the need to put in under floor heating. In
a still further example a metal weave web or hurrican fencing could
be used not only to add great strength but also to act as a
security barrier giving an indication if it is cut.
[0052] In the embodiment where the core is formed in two parts, an
additional layer may be provided between the core halves as well
as, or in addition to, between the core and one or both
facings.
[0053] Moulded expanded polystyrene cores in accordance with the
invention are so remarkably strong in compression that the
structural insulated panels require no further input in terms of
structural elements. There are no timber beams, steelwork etc.
Initial tests indicate that structural insulated panels in
accordance the invention might well be approved to build up to six
floors and even ten floors high without further structural
elements, hence opening up a potential further market in commercial
construction.
[0054] A number of other components which will be used in the
building of a house. These include a ring beam, of the same basic
material, which adds horizontal stability and acts as a lintel over
doors and windows, a box beam for extending panel spans by adding
rigidity to lengths, a corner section and a seismic joint, again
made from the same basic materials.
[0055] Intermediate floors, roofs etc. may all made from these
basic components in a factory environment, and the large pieces are
simply assembled on site. Once assembled, the whole can then be
clad in local materials (brick tiles, stone, timber, rendering
etc).
[0056] The surface of moulded cores has a better appearance than
that of hot swire cut cores of which the appearance has been marred
due to hot wire cutting judder and this could be used to impart a
quality image by moulding-in trade names or marks.
[0057] A further contribution to the good surface appearance is the
fact that normally a low pentane grade material can be used which
consists of smaller beads than the block moulding equivalent.
[0058] Exact dimensions are obtained since they are determined by
the mould dimensions. The accuracy obtained is, therefore, much
higher than in the case of block-cutting. It can be said that a
design disadvantage with moulded cores is that the range of sizes
offered must be limited, since mould costs are high and the mould
changing time is long compared to the resetting of a hot-wire
cutter. However, thickness adjustment can be easily achieved by the
incorporation of spacers between the mould surfaces.
[0059] For effective insulation and structural connection, the
structural insulated panels have to be provided with a system to
eliminate the formation of gaps in the insulation caused by
shrinkage or thermal contraction. In the case of cores cut from the
block, this requires an extra, thus costly, operation by grinding,
planing or milling. Moulded core panels, however, can be provided
with special features, thus eliminating secondary operations to
which reference will now be made. For example, recesses may be
moulded in along the edges of the opposite facing surfaces of the
cores by means of inserts in the mould so that the aligned recesses
of adjacent cores assembled to form a wall of a building for
example may receive respective elongate elements in the form of
strips, known as "biscuits", for use in joining adjacent cores
together without thermal bridging.
[0060] To keep the facings and the core cooperating with each
other, the joints between the facings and the core must be able to
transfer the shear forces between the faces and the core. The
joints must be able to carry shear and tensile stresses. It's hard
to specify the demands on the joints. A simple rule is that the
joints should be able to take up the same shear stress as the core.
The biscuit/recess joints guard against such problems
occurring.
[0061] Whilst cut recesses would cause the core to lose loose some
of its strength by the removal of material, the moulding process in
two individually moulded part cores causes the recesses to be lined
with a skin of fused cells that is integral with the surrounding
skin of fused cells, like the service line passageways, to prevent
any loss of strength.
[0062] Moulded two part EPS cores 200 mm wide can be produced to
the requisite dimensions in a core moulding machine at a density of
24 kg per cm and a flexural strength of 400 kn/m2. To achieve the
desired flexural strength using cores cut from the block, it would
be necessary to use block material expanded at a minimum density of
35 kg. per cm. As previously stated, the density across the block
would vary considerably and therefore it would be impossible to
implement accurate quality control procedures. Accuracy of hot wire
cutting would not give the dimensional tolerance required and the
percentage waste ratio would climb dramatically.
[0063] The invention also comprehends methods of constructing
buildings using any of the structural insulated panels defined
hereinabove and to buildings constructed of such panels and/or in
accordance with the method.
[0064] The advantages of moulded core structural insulated panels
made according to the present invention are manifold particularly
for the preferred EPS embodiment and are as follows:--
[0065] Cost effective--as compared with any other conventional
building system.
[0066] Mechanical Strength--Trials on this style of construction
material show it to be far superior in all performance criteria to
brick, timber or concrete structures of comparable size. A finished
building, e.g. a house, will also be earthquake and hurricane
proof.
[0067] Workable--Using standard tools can be adapted to suit
specific customer requirements.
[0068] Multi-skilled Constructors--once certification is achieved
the buildings/houses can be constructed by relatively low skilled
(or multi-skilled) workforce readily available.
[0069] Hidden Utilities--provision is easily made during moulding
for power, communications cables, water pipes etc. to be completely
hidden by engineering them directly into the moulded cores at the
outset, thereby solving the conduit problems. This eliminates all
types of costs relating to adding utilities after construction of
the walls and is a considerable improvement on the American SIPs
referred to previously in which conduits for service supply lines
are cut into the already formed core which takes time and results
in waste polystyrene and can cause core weakening.
[0070] Weather Strength--new, old and damaged components will meet
the highest standards of resistance against wind, rain, snow, sun
and frost.
[0071] Fire Resistance--of the two major constituents of the EPS
moulded core structural insulated panels, one is nonflammable and
has a two-hour fire rating and the other is self-extinguishing.
Neither gives off toxic fumes during a fire. Thus a home can be
built with out there being any combustible materials
whatsoever.
[0072] Moisture Resistance--the EPS moulded core structural
insulated panels are not susceptible to damage by water from
blocked gutters, breached damp proof course, leaking pipes, rain
exposure, etc.
[0073] Noise Attenuation--the use of high-density core material and
the thickness of the walls formed from the EPS moulded core
structural insulated panels components will give outstanding noise
attenuation performance. Vibration through the panels is virtually
impossible.
[0074] Long Life--the life of a brick and mortar house is around
100 years. Beyond that a major expense is required to keep it in
good order. The design life of the EPS moulded core composite
component homes will be targeted as 200 years. Information from the
USA rates their SIP constructions relying on additional structural
support from timber elements as having a 300-year life.
[0075] Thermal Performance--It is considered that EPS moulded core
structural insulated panels will be the best thermally performing
building material in the world. The u value, a measure of thermal
resistance of a material, of the moulded core panel remains
constant throughout the life of the component.
[0076] Readily Available Materials--all the main components of the
EPS moulded core structural insulated panels will be available as
commodity items or will be manufactured in-house.
[0077] Resistance to Organisms--none of the EPS moulded core
structural insulated panels is prone to attack from insects,
rodents, fungus or rot. If a particular problem exists in a certain
part of the world, the product can readily accept fungicides,
insecticides etc to resolve these issues.
[0078] Toxicity--the materials from which the EPS moulded core
structural insulated panels are made contain no toxins, carcinogens
or odours. EPS itself can actually be used in certain food grade
applications.
[0079] Maintainability--there is no requirement for ongoing
maintenance. The EPS moulded core structural insulated panels are
resilient and will resist minor impact damage, e.g. from a slow
moving vehicle. For serious impact damage, the building can be
readily repaired using replacement panels.
[0080] Additions--the form of construction lends itself very well
to extensions for additional rooms, bedrooms, garages etc. as the
family grows. This fits well with many cultures where family
dwellings start small and grow as funds and demands so dictate.
[0081] Technically Approved--thinner SIPs than the moulded core
composite building components are well accepted in the United
States. Tests that have already been carried out by BRE show that
the EPS moulded core structural insulated panels exceed racking
resistance requirements for both stiffness and strength given in
BS5268:part 6: Section 6.1 to resist wind and vertically imposed
loads in domestic buildings.
[0082] Environmentally Friendly--the materials from which the EPS
moulded core structural insulated panels are made are
environmentally friendly. They offer substantial energy savings;
over 80% of the components (by volume) can be recycled; and 100% of
each component can be used in a power plant as fuel, thereby
utilising the energy expended in its production: so it is energy
efficient
[0083] In order that the invention may be more fully understood,
some embodiments thereof will now be described, by way of example,
with reference to the accompanying drawings in which:--
[0084] FIGS. 1 and 2 are photographs of the raw polystyrene
material and pre-expanded polystyrene beads respectively used for
manufacturing ESP moulded cores of a structural insulated panel
made by a method illustrated in FIGS. 3 and 4;
[0085] FIGS. 3 and 4 are schematic drawings illustrating one method
of manufacturing a structural insulated panel (SIP) having a custom
made/individually EPS moulded two part core and reinforcing
facings, in accordance with one embodiment of the invention;
[0086] FIG. 5 is a perspective view of a two part hermaphrodite
mould for manufacturing EPS moulded cores of which two such cores
form a two part core in the structural insulated panel made in the
method of FIGS. 3 and 4;
[0087] FIG. 6 is a perspective view of the lower part of the
hermaphrodite mould of FIG. 5;
[0088] FIGS. 7, 8 and 9 are a side elevation, bottom plan view and
top plan view respectively of one EPS moulded core part made in the
mould of FIGS. 5 and 6;
[0089] FIG. 10 is a cross-section taken along the line A-A of FIG.
8 of two EPS moulded core parts made in the mould of FIGS. 5 and 6,
positioned one above the other in vertical alignment;
[0090] FIG. 11 shows the two EPS moulded core parts of FIG. 10
glued together to form a two part EPS moulded core:
[0091] FIG. 12 is detail view to an enlarged scale of one part of
the two part EPS moulded core of FIG. 11;
[0092] FIG. 13 is a perspective view of a structural insulated
panel comprising the two part EPS moulded core of FIGS. 11 and 12
sandwiched between, and laminated by gluing to, two facings;
[0093] FIG. 14 is a perspective view of a part of a corner
structural insulated panel comprising the two part moulded core of
FIGS. 11 and 12 sandwiched between, and laminated by gluing to,
four facings;
[0094] FIGS. 15 and 16 are enlarged detail views of two adjacent
structural insulated panels showing one method of joining the two
panels together, for example to form a section of a wall of a
building, just before and before and after joining together,
[0095] FIG. 17 is perspective view of with parts cut away of a wall
section comprising three adjacent structural insulated panels
joined together in the manner shown in FIGS. 15 and 16;
[0096] FIG. 18 is an exploded perspective view of a plurality of
two part EPS moulded core structural insulated panels showing how
the panels are joined together to form a wall of a building;
[0097] FIG. 18a is diagrammatic view of the wall of a building
formed of the joined together panels of FIG. 18;
[0098] FIG. 19 is an exploded perspective view of a plurality of
two part EPS moulded core structural insulated panels having window
and door apertures and showing how the panels are joined together
to form a wall of a building;
[0099] FIG. 20 is a perspective view from the front of a building,
with the front removed, to show the interior and of which the
walls, floors and roof are made from two part EPS moulded core
structural insulated panels according to the invention;
[0100] FIGS. 21 and 22 are cross sectional and front elevational
views respectively of a seismic joint joining together two part EPS
moulded core structural insulated panels according to the invention
and forming a floor and the walls of a building and which may be
used to join the first floor to the walls of the building of FIG.
20 to each other;
[0101] FIGS. 23 to 25 are part cross-sectional views of the
components of a box beam using two part EPS moulded core structural
insulated panels according to the invention;
[0102] FIG. 26 is a part cross-sectional view of a box beam
assembled from the components of FIGS. 23 to 25;
[0103] FIG. 27 is a part perspective view of a one-piece
individually EPS moulded core or use in making a structural
insulated panel in accordance with another embodiment of the
invention;
[0104] FIGS. 28 and 29 are enlarged detail views of two adjacent
structural insulated panels using the core of FIG. 27 showing one
method of joining the two panels together for example to form a
section of a wall of a building, just before and before and after
joining together,
[0105] FIG. 30 is a part perspective view of a one-piece
individually EPS moulded core made of expanded polystyrene for use
in making a structural insulated panel in accordance with a further
embodiment of the invention; and
[0106] FIGS. 31 and 32 show graphs.
[0107] In the drawings the same reference characters have been used
to designate the same or similar parts.
[0108] Referring to FIGS. 1 to 6 of the drawings, a low pentane
grade polystryrene raw material, which consists of smaller free
flowing beads 1 than the block moulding equivalent from which
conventional EPS cores are made, is stored in a storage container 3
shown in FIG. 4 from whence it is subjected to the three stage
process involving pre-expansion, cooling and maturing and
moulding/secondary expansion.
[0109] The raw polystyrene beads 1 are fed to the first,
pre-expansion, stage 5 where the beads 1 are pre-expanded to 20-40
times their original volume by heating to a temperature of about
100.degree. C., using steam as the heat carrier in the manner
previously described herein. The pre-expanded beads which are
indicated by the reference 6 in FIG. 2 are cooled and dried in a
fluidised bed dryer 7 (FIG. 4) before being stored to mature in
storage silos 8, as what are, in effect, closed cells, again as
previously described herein.
[0110] The third and final moulding/secondary expansion stage 9
(FIG. 3) comprises an hermaphrodite mould 10 having two mould parts
10a and 10b as will be apparent from FIGS. 5 and 6. The walls of
the mould parts 10a and 10b define a multiplicity of nozzles or
vents 12 and air injectors (not shown) for a purpose to be
described.
[0111] The mould part 10a defines a mould cavity that is formed
with a peripheral recess (not visible) which accommodates a
correspondingly shaped mould insert (not shown) that projects into
the mould cavity during moulding. The mould part 10b is formed with
a grid 14 (see FIG. 6) of interconnecting longitudinally and
transversely extending channels 16 and 18 respectively which are in
alignment with respective slots 16a and 18a in the walls of the
mould part 10a which slots and channels accommodate a
correspondingly shaped grid mould insert when the mould is
hydraulically or pneumatically closed to commence a moulding
operation.
[0112] Additionally, the mould part 10b is provided with
complimentary male/female locating means constituted by three
projections 20 towards one end (the right hand end, as illustrated
in FIG. 6) of the mould part 10b and three identically positioned
complimentary recesses 22 toward the other end (the left-hand end
as illustrated in FIG. 6) of the mould part 10b.
[0113] The pre-expanded and matured beads 6 are blown from the
storage silos 8 into the mould cavity in the mould part 10a of the
closed mould 10, using air injectors (not shown) with the air
escaping via the nozzles or vents 12. Each mould part 10a, 10b is
provided with its own bolted on steam chamber (not shown) which is
in communication with the nozzles or vents 12 through which steam
is introduced into the pre-expanded and matured bead 6 filled mould
cavity in the mould part 10a of the closed mould 10.
[0114] In the closed mould 10, the beads 6 are heated to
temperatures between 110.degree. and 120.degree. C. and are further
expanded with steam which is confined to filling up the free volume
of the mould cavity which compresses beads together because, being
contained by the mould, they cannot expand freely. This, therefore,
creates internal pressure in the mould cavity so that the beads
fuse together along their boundary faces, assisted by any residual
stickiness of the circumference of the individual cells due to the
heating to form an individually (custom) EPS moulded shaped core
part. After a cooling (pressure reduction) period, usually using a
vacuum to remove any moisture, the moulded core part is
dimensionally stable and can be released from the mould 10. The
moulded core part is indicated by the reference 24 and is
illustrated in FIGS. 7 to 9. Any remaining expanding agent (pentane
gas) is expended during moulding so that the moulded core part 24
does not contain any residual expanding agent. The individually
(custom) moulded shaped EPS core part 24 part has a surrounding
skin 26, as shown in FIG. 12 and a grid of moulded, skin covered
channels. Only the channel 18b is visible in FIG. 12.
[0115] The spacing and number of nozzles or vents 12 and the total
nozzle/vent area ensures that the steam reaches all parts of the
mould cavity and thus provides moulded core parts 24 of which the
density is substantially uniform in that it does not vary up or
down more than .+-.2.0%.
[0116] Referring more particularly to FIGS. 7 to 9, the surface 28,
which is the upper surface as illustrated in FIGS. 7 and 9 of the
individually moulded core part 24, has a peripheral recess 30
therein, i.e. a recess that extends all the way around its
periphery. This peripheral recess 30 is formed by the mould insert
in the recess in the mould part 10a and which projects into the
mould cavity during moulding. A grid 14a of longitudinally and
transversely extending channels 16b and 18b respectively are formed
in the surface 32 by the mould insert grid that occupies the grid
14 of channels 16 and 18 and slots 16a and 16b during moulding.
Also, it will be appreciated from FIGS. 7 and 8 that the three
projections 20 and three identically positioned complimentary
recesses 22 of the mould part 10b are responsible for forming the
three recesses 20a and complimentary projections 22a in the
undersurface 32, as illustrated, of the moulded core part 24.
[0117] When two (mirror image) moulded core parts or halves 24 have
been produced in the mould 10 and successively demoulded, they are
conveyed to an adhesive coating stage 34 (FIG. 3) where their
surfaces 32 are coated with an MCPU adhesive. Then, the two
adhesive coated core parts 24 are conveyed to a pressing and
setting stage 36 (FIG. 3) where one core part 24 is turned through
180.degree. relative to the other core part 24 to occupy the
positions shown in FIG. 10. In this position, the purpose of the
complimentary projections 22a and recesses 20a will readily become
apparent. This is because at the left hand end as illustrated, the
recesses 20a of the upper core part 24 align with the projections
22a of the lower core part 24 and at the right hand end as
illustrated, the projections 22a of the upper core part 24 align
with the recesses 20a of the lower core part 24. The transverse
channels 18b of the upper and lower core parts 24 as well as the
longitudinal channels (not visible) are also aligned.
[0118] Thus, when the upper and lower core parts 24 are pressed
together at the pressing and setting stage 36 to adhere the one to
the other as shown in FIG. 1. The aligned complimentary projections
22a and recesses 20a inter-engage precisely to locate the two core
parts 24 with respect to each other and the aligned channels 16b,
18b form a matrix of passageways 38 for service lines. Once the
adhesive has set, a two part custom moulded core 40 is produced
which is conveyed to a quality check and assurance stage 42, as
shown in FIG. 3. The adhesive penetrates into the interstices
between the closed cells of the two mould parts 24 to form a layer
which is not shown in FIG. 12 and extends between the two mould
parts 24 so that there is no plane of separation between the two
mould parts. Indeed the bond made by the adhesive layer is stronger
than the EPS material of the moulded parts 24.
[0119] The next stage which is indicated by the reference 46 in
FIG. 3 involves the application of an MCPU adhesive to one surface
of each of two panel facings, e.g. of OSB, ply wood or cementious
board. The adhesive coated surfaces of the facings are then
conveyed to a stage 48 (FIG. 3) where they are applied carefully to
the oppositely facing surfaces 28 of the moulded core 40. To ensure
long lasting adhesion under load bearing conditions, the moulded
two part core 40 with its applied facings is conveyed to a pressing
and setting/curing stage 49 (FIGS. 3 and 4) where a mechanically or
pneumatically operated press is used. A completed structural
insulated panel (SIP) 50 and which is illustrated in FIG. 13 has a
core 40 sandwiched between, and adhesively bonded to, two facings
52.
[0120] FIG. 14 shows a corner SIP 50 which, because the core 40
actually forms the corner, is virtually moisture in-penetrable as
compared to conventional SIP corners formed by abutting separate
SIPs against each other. It will be seen in each case that the
recesses 30 are disposed inwardly of the facings which define with
the core 40, a slot 30a for a purpose to be described with
reference to FIGS. 15 to 17.
[0121] Referring to FIG. 15, the slots 30a receive strips which are
called biscuits 54 which may be adhered to those parts of the core
40 and facings defining the slots 30a to join adjacent SIPs 50
together, as shown in FIGS. 16 and 17. Additionally, the abutting
faces of adjacent SIPs 50 may be adhered together, optionally as
shown in FIG. 16 by forming adhesive receiving channels 56 therein
so that in FIG. 16 there is shown a longitudinally extending bead
of adhesive 56a occupying the channels 56. The longitudinally and
transversely extending passageways 38 for supply lines can be seen
in FIG. 17.
[0122] FIG. 18 shows how SIPs 50 may be assembled to form a wall of
a building which is shown completed in FIG. 18a, as indicated by
the reference 57 by the use of biscuits 54 in the manner shown in
FIGS. 15 to 17 and by extending the facings 52 upwards beyond the
cores 40 to provide top channels 60 for elongate elements 58. It
will be seen that the upper SIPs 50 have been shaped to fit with an
unshown pitched roof.
[0123] In FIG. 19, apertures 62 for doors and windows are cut in
SIPs 50 forming a wall 64 and are provided with respective frames
66 that fit in channels 60 formed by extending the facings 52
beyond the cores 40. The SIPs 50 are supported on a foundation 68
by means of an elongate sole plate element 58 engaging in a channel
60 in each SIP 50.
[0124] The building 70 illustrated in FIG. 20 is a two storey
(floor) building with a foundation (ground floor) 72, walls 74,
first floor 76, roofs 78 and a roof supporting beam 80 acting as an
I-beam in which the core 40 is the equivalent of the I-beam web and
the facings 52 are the equivalents of the I-beam flanges, are of
SIPs 50. The first floor 76 may be joined to the wall SIPs 50 by
means of the joint 90 illustrated in FIGS. 21 and 22 to which
reference will now be made. The joint 90 comprises a channel
element 91 supporting the second storey wall on the first floor 76
with a dowel element 92 extending through the channel element 91
and into the cores 40 of the SIPs 50 of the first floor and ground
floor walls. The joint 90 has a capping 93 that fits over the
projecting part 94 of the first floor 76.
[0125] Referring to FIGS. 23 to 25, there is shown the elements of
an SIP having cores 40, facings 52 and biscuits 54 that are adhered
together into a box beam which is shown assembled and indicated by
the reference 100 in FIG. 26. The box beam 100 is utilised for
extending SIP spans by adding rigidity to lengths. An I-beam such
as is mentioned in the preceding paragraph can be substituted for
the box beam 100 as required by load demands.
[0126] The embodiment of core 40a shown in FIG. 27 differs from the
two part core 40 of the previous drawings in that the core 40a is a
one-piece custom made individually moulded EPS block type core
having a maximum thickness of 100 mm. As will be apparent from
FIGS. 28 and 29, two adjacent SIP's 50 are joined together in a
similar manner as described with reference to FIGS. 15 and 16 for
the SIPs 50 with the two-part cores 40 except that there are no
channels 56 which receive an adhesive bead 56a. The core 40a will
be made in a mould that functions in the same way as the mould 10
and the upper mould part will have a recess for receiving a
complimentary mould insert to produce the recess 30.
[0127] Except for the recesses for mould inserts, the simple
individually moulded EPS block core 40b of FIG. 30 may be made in
such a mould.
[0128] The cores 40a and 40b are sandwiched between and bonded to
unshown facings 52 to produce an SIP 50.
[0129] In FIG. 31 there are two graphs which illustrate a
comparison between cores that are rigid and weak in shear
respectively. In the upper graph, the trace shows that the core
tested is rigid in shear, i.e. a two part moulded core 40 of
substantially uniform density, and is the acceptable deflection for
use in an SIP to be placed in long term compressive loading such as
when used in the wall of a building.
[0130] On the other hand in the lower graph, the core tested is
weak in shear. i.e. a core of variable (low) density such as that
cut from an EPS block because the trace shows bad deflection which
would be an undesirable quality for use in an SIP to be placed in
long term compressive loading such as when used in the wall of a
building.
[0131] Some typical values of flexural strength of moulded EPS
cores versus those of cores cut from EPS block are set out in the
graph shown in FIG. 32 and are self evident. Core shrinkage is in
the order of 0.5-0.6%, this value being obtained after two or three
months.
[0132] Prototype testing shows representative results according to
the following Table which are given purely by way of example to
enable the invention to be more readily understood.
1TABLE Panel Panel stiffness Estimate stiffness in of in stiff-
strength Average failure Failure Vertical ness cycle, cycle, panel
load, load, Panel load R.sub.stiff R.sub.str stiffness,
F.sub.max,ext F.sub.max ref. (kN) (N/mm) (N/mm) R (N/mm) (kN) (kN)
Test series 1 MPR1 0 4613 5101 4857 25 33.59 MPR2 0 5010 5063 5023
32 47.54 MPR3 0 4294 5418 4856 42 39.54 MPR4 0 2951 4986 3968 40
34.44 MPR5 0 4225 5677 4951 40 38.80 MPR8 5 6558 7136 6847 60 45.02
MPR7 5 6987 6983 6975 48 44.78 MPR8 5 5058 5821 5439 44 54.02 MPR9
5 5861 7176 6519 46 49.28 MPR10 5 5521 7627 6574 48 48.03 Test
series 2 MIP1 0 3543 3894 3718 36 26.46 MIP2 0 642 877 759 10 5.70
MIP3 0 392 553 472 8 6.00
[0133] Various modifications may be made to the embodiments
described without departing from the inventive concepts defined in
the introductory portion of this specification. For example, the
EPS moulded cores may be cut to smaller sizes of rectangular shape
or different shapes depending upon their location and/or
application (see FIG. 18 for example) either before or after
bonding of the facings 52. In such instances, it may be necessary,
depending upon load requirements, to provide the cut surface of an
EPS moulded core with a facing such as a biscuit to restore any
losses in strength that might conceivably occur.
* * * * *