Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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K 1637
PROCESS FOR PROVIDING THERMAL INSULATION
This invention relates to a process for providing thermal
insulatlon -ln a wooden-framed building.
US Patent No. 4,019,297 discloses a construction panel for
incorporation into a building structure, which comprises a frame
consis~ing of spaced-apart vertical studs and transverse top and
bottom plates wider than said studs, an insulation board secured to
one face of the rame and within a cavity formed by said plates and
studs, and a concrete composition layer comprising expanded mica,
expanded polystyrene and mortar cement applied to the exposed
outwàrdly-facing side of the insulation board, which layer has a
filament mesh reinforcement embedded therein. Such construction
panels are manufactured in a factory and transported to a building
site or incorporation into a building.
In the case of buildings having a brick outer wall and a
cavity between the outer wall and an inner wall, very satisactory
thermal -lnsulation may be provided in situ by introducing into the
cavity expanded polymer particles bound into a cohesive mass with a
synthetic polymer latex binder. Such a process ls described for
example in UK Patent Specification No. 1,602,3~1.
Although such thermal insulation is very satisfactory and cal.
be made acceptably flame retardent for use in brick buildings, the
degree of flame retardency obtainable is less ideal for application
to wooden-framed buildings.
A wooden-framed building i9 commonly comprised of a wooden
frame constructed from 4 inch x 2 inch ~10 cm x 5 cm~ section
timber (studding) (e.g. pinewood) which is clad on the outside
with, for example, shiplap boards of wood or plastics material
(e.g. polyvlnylchloride), asbestos sheeting or marine-grade
plywood, and on the inside with, for example, plasterboard,
fibreboard, chipboard or plywood. This mode of construction leaves
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a series of cavity compartments bounded at the sides by wall
cladding and at the edges by wooden frame members. These cavlty
compartments are commonly of the order of four feet x two feet x
four inches (122 cm x 61 cm x 10 cm) in dimensions. An alternative
form of wooden-framed building may have plywood cladding on the
outside of the wooden frame and the outside of the building may be
a brick wall spaced from the plywood cladding.
It is an ob;ect of this invention to provide thermal
- insulation sui~able for wooden-framed buildings.
According to the present invention there is provided a process
for providing thermal insula~ion in a wooden-framed building which
comprises introducing into individual wall-cavity compartments
thereof a flowabl~ lightweight concrete composition comprising an
aqueous s~urry containing cement and cellular polymer partlcles an~
allowing the concrete to harden.
Expanded polystyrene particles are particularly suitable for
use as the cellular polymer particles in the process of the
invention, but other types of cellular, expanded polymers may also
be used. As is well known, expanded polystyrene particles are
conveniently prepared from expandable particles manufactured in the
form of beadq or pearls by suspension or emulsion polymerisation
techniques, the expanding agent (e.g. pentane) being incorporated
therein during or after poly~erisation. Upon heating of the
expandable pearls or beads, "pre-expansion" occursl yielding
expanded polystryrene particles suitable for use in the process of
this invention. "Pre-expan~ion", which is a well-known step in the
cellular polystyrene art, comprises s~eaming the expandable beads
or pearls to give an expansion by a factor oE 20 to 30, or eve~ as
much as 70, times their original-~olume, and, during cooling,
allowing air to penetrate into the individual cells to raise the
internal pressure to atmospheric pressure. These expanded cellular
polystyrene particles have a spherical shape, an apparent bulk
density of, for example 6 to 100 g/l, and free flowing properties.
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In the process of the invention, use of cellular polymer par~icles
having a bulk density in the range 12 to 16 g/l ls preferred, The
cellular polymer particles may range in diameter from 1 to 10 mm or
more. Cellular polymer particles having diameters in the range 2 to
10 mm, preferably 3 to 5 mm, are preferred.
Any suitable hydraulic cement may be employed in the aqueous
slurry, but Portland cement is preferred.
Flowable lightweight concrete compositions wherein the water:
cement ratios in the aqueous slurry is în the range 0.42 : 1 to
0.44 : 1 have been found to be very suitable. Those skilled in the
art will appreciate ~hat the slurry has to contain sufficient water
to achieve complete wetting of the cellular polymer particles for
the composition to be capable of introduction into the
compartments, and for the resulting hardened concrete in a
compartment to be a coherent block. How~ver, the water content of
the slurry has to be sufficiently low to avoid water draining ~o
the bottom of the compartment before hardening (setting) of the
concrete.
If desired the aqueous slurry may optionally contain
additional components, e.g. to assist in wetting of the cellular
polymer particles. Such components include synthetic polymer latex
binders such as aqueous colloidal suspensions of styrene-butadiene
copolymers, acrylic copolymers, butadiene-acrylonitrile polymers,
vinylidene chloride copolymers, butyl rubber, isoprene or polym~rs
or copolymers of vinyl alkanoates such as vinyl acetate, vinyl
propionate or copolymers of vinyl acetate with higher vinyl esters
or with vinyl chlor~de or ethyleneO The binders sold under the
trade mark "Vinamul" (e.g. "Vinamul" 6975, 3252 and 3452) (all ex
Vinyl Products) are very suitable.
Other optional additional components include antifungal
agents, plasticizers, thickening agents, surface active agent~
(e.g. "Teepol" (registered ~rade mark)) in an amount of 0.1% w~
based on the water in the slurry) and slliceous or
siliceous-aluminous materials such as pozzolans.
It i9 preferred for the relative quantlties of cement and
cellular polymer particles in the flowable lightweight concrete
composition to be such that the resulting hardened concrete has a
density in the range 150 to 600 kg/m3.
l'he f]owable lightweight concrete composition is conveniently
introduced into the individual wall compartments by injection
through a single hole drilled in the outer cladding near the top of
each compartment. If desired the flowable lightweight concrete
composition may be premixed and transported from a mixlng or
storage vessel to the wall compartment, for example by means of
flexible pipes using a peristaltic pump.
Alternatively use may be made of a filler gun to which the
cellular polymer particles and a cement mix (containing the cement,
water and any other ingredients of the eventual aqueous slurry) are
fed separately, but at appropriate relative rates, and wherein the
flowable lightweigh~ concrete composition is formed immediately
before entering the compartment. Suitable such filler-guns are
described in detail in UK Patent Specification No. 1,600,096 and
European Patent Application Publication No. 53411. Such filler guns
co~prise a hollGw body having an outlet at one end, a binder inlet
for liquid binder at the other end, and a side inlet for granular
or particulate solid, which side inlet is directed towards the
outlet at an angle of less than ~0 with respect to the direction
of flow of liquid binder from the binder inlet to the outlet in
operat.ion of the gun. When used ln the process of this invention,
the c~llular polymer particles are fed through the side inlet and
the cement mix is fed through the blnder inlet. The csment mix may
be held in suspension in a pressure vessel and fed to the gun via a
flexlble pipe under pressure. Alternatively, the cement mix may be
mixed in a conventional concrete mixer and pumped to the gun, for
example via a flex-lble pipe by means of a peristaltic pump. If
desiredJ the cemen~ mix may be pumped continuously in a loop system
and diverted to the gun as required. Such use of a loop system
assists ln avoiding settling of solids from the cement mix in the
flexible pipe.
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The invention also includes wooden framed buildings provided
with therma~ insulation by a process according to the invention.
Thermal insulation provided by the proce~s of the invention
has a number of advantages. The process itself is a method which is
readily applied to existing buildings, and greatly reduces heat
transfer through the walls of the building to which it is applied.
The thermal insulation is flame resistant and may enhance the
strength of the building. On hardening and drying, the thermal
insulation is air-permeable, which minimizes risk of damp in the
wooden structure of the building. Furthermore, transmission of
impact sound is reduced in those parts of the building to which the
process of the invention is applied.
The invention will be further understood from the following
examples thereof, wherein parts are parts by weight.
I5 EXAMPLE 1
A cement mix was prepared by gradual addition of 35 parts of
water to 80 parts of Portland cement with mixing. Thereafter 10
parts of expanded polystyrene beads prepared by pre-expansion of
expandable polystyrene beads sold by ~he Royal Dutch/Shell group of
companies under the reglstered trade mark "Styrocell R 551" having
a density of 12.6 kg/m3 and bead diameter of 3-5 mm were mixed into
the cement mix. The resulting flowable lightweight concrete
composition was in the form of an aqueous slurry.
This flowable lightweight concrete composition was of
sufficiently low viscosity for in~ection into a wooden~framed wall
cavity compartment 122 cm x 61 cm x lO cm. The concrete remained
homogeneous until it had hardened, with no draining o~ water to the
bottom of the compartment. Drying sbrinkage was low (of the order
of 0,02%), the resulting thermal insulation (the hardened
lightuelght concrete) had a denslty of 150 kg/m~ and thermal
conductivity at 5% water content lower than 0.10 W/m C. The
thermal insulation was flame resistant.
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EXAMPLE 2
The process of Example 1 was repeated but using 270 parts of
water, 640 parts of ~he cement and 10 parts of the e~panded
polystyrene beads.
The resulting concrete also remained homoge.n ous until it had
hardened, with no draining of water to the bottom of the
compartment. Drying shrinkage was low (of the order of 0.02%), the
resulting thermal insulation (the hardened lightweight concrete)
had a density of 600 kg/m3 and thermal conductivity at 5% water
content lower than 0.10 W/m ~C. The thermal insulation was flame
resLstant.
