Concrete Canvas
Concrete
Canvas
Concrete Canvas (CC) is a flexible, concrete impregnated
fabric that hardens when hydrated to form a thin, durable,
water proof and fire resistant concrete layer. CC allows
concrete construction without the need for plant or mixing
equipment. Simply position the Canvas and just add water.
CC consists of a 3-dimensional fibre matrix containing a
specially formulated dry concrete mix. A PVC backing on
one surface of the material ensures the material is water
proof. The material can be hydrated either by spraying or
by being fully immersed in water. Once set, the fibres
reinforce the concrete, preventing crack propagation and
providing a safe plastic failure mode.
CC is available in 3 thicknesses: CC5, CC8 and CC13, which
are 5, 8 and 13mm thick respectively. CC is used in a
variety of civil infrastructure applications, such as
ditch lining, slope protection and capping secondary
containment bunds.
Compared to traditional concrete solutions, CC is faster,
easier and, more cost effective to install and has the
additional benefit of reducing the environmental impact of
concreting works by up to 95%.
Concrete
Canvas Shelters
Concrete Canvas Shelters (CCS) are rapidly deployable
hardened shelters that require only water and air for
construction.
CCS have two major advantages over conventional tented
shelter:
- Operational: CCS enable a hardened structure from day
one of an operation. They provide much better
environmental protection, increased security and vastly
improved medical capability.
- Financial: CCS have a design life of over 10 years,
whereas tents wear out rapidly and must then be replaced.
CCS are a one stop solution, saving effort and cost over
the lifetime of medium to long term operations.
The key to CCS is the use of inflation to create a surface
that is optimised for compressive loading. This allows
thin walled concrete structures to be formed which are
both robust and lightweight.
CCS are constructed from Concrete Canvas, bonded to the
outer surface of a plastic inner which forms a Nissen-Hut
shaped structure once inflated.
- Packaging -- CCS are supplied in polyethylene, airtight,
water proof, rot proof sacks within ISPM15 heat treated
timber/ply panel crates.
- Modularity -- CCS structures are designed as part of a
modular system; units can be docked together to create
arrays of structures to suit operational requirements.
- Inflatable Inner -- Each CCS has a flame retardant
reinforced polyethylene inflatable inner with internal
hanging tabs (maximum load 20kg/tab). Disinfecting with
high chlorine concentration will not damage the inner.
- Requirements for deployment -- Both CCS variants can be
deployed by 2 people. A CCS50 will require a vehicle or
winch to aid with the unfolding of the shelter prior to
inflation. Each shelter is provided with the ground pegs
required for inflation.
CCS are deployed in four stages; Delivery, Inflation,
Hydration and Setting.
IMPREGNATED
FABRIC
US8287982
The invention provides a knitted spacer fabric having a
tightly knitted bottom layer, a more loosely knitted upper
layer and pile yarns extending across the space between
the lower and upper faces. Settable material, e.g. cement,
is introduced into the space between the upper and lower
faces and can be caused to set by the addition of a
liquid, e.g. water. Until set, the fabric is flexible and
can be shaped but after the material in space has set, the
fabric is rigid and can be used as a structural element in
a wide range of situations, e.g. to form a cover of a
prefabricated shelter, a track-way for vehicles,
pedestrians or animals; a shelter by applying the fabric
to a framework; formwork for casting concrete; barriers,
e.g. to line tunnels; to repair structures, e.g. roofs; to
form floors or damp proof structures; to reinforce earth
structures, e.g. river banks; to provide flood defences;
or to repair existing pipes, including buried water pipes
or to construct new pipes.
TECHNICAL
FIELD
The present invention relates to a fabric impregnated with
a material that, when mixed with a liquid, will set. Such
fabric has numerous applications.
TECHNICAL
BACKGROUND
WO 2005/124063 describes a shelter that includes a ground
sheet and a cover; the space between the ground sheet and
the cover can be inflated by pumping air into the space to
raise the cover and form the shelter. The cover is made of
a fabric that has been impregnated with cement; the fabric
may be a type of felt known as “wadding”, which is a loose
non-woven fabric. Immediately before the interior space is
inflated, the cover is wetted with water, so that, after
inflation, the cement in the cover sets and forms a rigid
shell that acts as a self-supporting roof for the shelter,
which is particularly useful in providing temporary
accommodation in emergency areas.
Spacer fabric is a known material and comprises a top face
layer, a bottom face layer and pile yarns extending
between the two faces. It is commercially available, for
example from Culzean fabrics of Kilmarnock, United
Kingdom; Scott and Fyfe of Tayport, Fife, United Kingdom
and W Bull and Son Ltd (Baltex) of Ilkestone, United
Kingdom. It is used to manufacture garments and other
articles where the fabric must be thick but light and/or
where the fabric should include an air gap, for example in
cycle helmets, boot soles, fireman's clothing, body
armour; mattresses and bandages; climate-control seating
in vehicles. The pile yarns are self-supporting to space
the two faces apart by a desired distance and to resist
crushing forces, i.e. forces acting perpendicular to the
plane of the faces. The thickness of the spacer fabric is
determined during manufacture by choosing an appropriate
length for the pile yarn. The yarns used for forming the
two faces can be the same or different from each other and
from the pile yarns so that it is possible to choose the
properties of the two face layers and of the pile to
provide the desired properties. Among the fibres employed
are polyethylene, polyester, Nomex, Kevlar, polyamide and
microfibre (Nomex and Kevlar are trademarks).
JP-A-04327272 discloses a woven or knitted lattice-like
fibre sheet to which is applied a composition containing
all the components of a thermosetting resin, and
containing a large proportion of plasticizer. The resin
composition is cured to provide a sheet having high
flexibility, high strength, low elongation and good shape
stability. Because of the high amount of plasticizer in
the resin, the resin is flexible and so allows the sheet
to be wound up on a roll.
U.S. Pat. No. 5,461,885 describes a hardenable substrate
that is used for forming casts and splints for
immobilising patients' limbs and joints that have been
fractured, broken or strained. The substrate is formed of
a fabric having two spaced-apart webs; a hardenable liquid
composition is drawn into the space between the webs by
capillary action and allowed to set. The liquid
composition may be a resin or a liquid dispersion of
plaster of Paris. The hardenable liquid sets in situ
shortly after it has been added to the fabric.
US 2003/0077965 discloses the use of a spacer fabric in a
resin infusion process or a resin transfer moulding
process in which liquid resin is introduced into the
fabric and allowed to cure/harden.
DISCLOSURE
OF INVENTION
According to the present invention, there is provided a
fabric comprising:
a first face;
a second face separated from the first face by space;
self-supporting pile yarns extending between the first and
second faces that maintain the first and second face in a
spaced-apart arrangement; and
a solid powder material, located in the space between the
first and second faces, which material is capable of
setting to a rigid or semi-rigid solid mass on the
addition of a liquid or on exposure to radiation, e.g. UV
radiation.
The settable powder material may be settable on the
addition of water and in one embodiment may comprise
cement, optionally together with sand or fine aggregates
and/or plasticizers and other additives found in cement or
concrete compositions, that will set to solid cement or
concrete on the addition of water or a water-based
solution. Alternatively, the settable material may be a UV
settable material or one component of a multi-part curable
resin that cures when two or more liquid components are
mixed together, e.g. an epoxy resin system.
The amount of settable material in the space in the fabric
is preferably such that, particularly when the material
has set, it occupies substantially the whole of the space
between the first and second faces.
The settable powder material can be easily loaded into the
fabric and, in the case that it is hardened by the
addition of a liquid, the liquid can rapidly penetrate
between the powder particles to form a composition that
will set over time.
The settable powder material and/or the liquid can include
additives e.g. flexiblizers, foaming agents, fillers,
reinforcement materials etc. that are known in the art in
connection with the settable materials concerned.
The first and the second faces may be formed of yarns and
the yarns of the two faces may be the same as each other
or different.
The settable material is preferably added to the space
through pores formed in the first face of the fabric, in
which case, the first face will have pores that are large
enough to allow the material to be placed in the fabric.
However, after the material has been placed in the fabric,
it is desirable to prevent it falling out through the
first face and several techniques can be applied to
achieve this aim.
Firstly, a further layer may be bonded onto the first face
after the settable material has been introduced into the
fabric. This further layer may be permeable to the liquid
used to cause the settable material to set and, if the
permeability is brought about by the presence of pores in
the bonded layer, such pores should be sufficiently small
to prevent the settable materials from falling through the
first face material. Any suitable layer may be used to
seal the first face, e.g. a PVC layer, which can be
secured to the upper face by a variety of techniques, for
example by thermal welding or by means of an adhesive.
Alternatively the layer may be formed of a curable paste
which is subsequently cured, e.g. using heat. Such a layer
is preferably thin, typically less than or equal to 0.5
mm. The layer may be flexible to maintain the flexibility
of the overall fabric prior to setting. Additional layers
may be applied to the sealing layer by a variety of
techniques, for example by thermal or chemical welding or
by means of an adhesive. One such layer could by way of
example be a damp-proof layer for applications, which
could find application in the construction industry or
tunnelling.
Secondly, the first face may be made of, or include, an
elastomeric yarn so that the upper face can be stretched
to enlarge pores within the face to allow the settable
material to be introduced into the fabric but, once the
material has been added to the fabric, the stretching
forces can be released, to close the pores to a size such
that the settable material cannot readily escape through
the first face.
Thirdly, the first face can be treated after the settable
material has been introduced into the fabric to close the
pores of the first face. For example, it is possible to
treat the first face by applying a sealing material such
as an adhesive or to subject the first face to solvent
treatment to fully or partially close the pores. In one
example, a PVC paste may be applied (for example using a
scraper) to the first face and cured for example by heat,
e,g. by means of radiative heaters or hot air blowers.
Fourthly, the first face can be knitted from a fibres that
will shrink when heated, thereby enabling the settable
materials to be introduced through a knit having pores
sufficiently open to allow the particles to pass through;
after the particles of the settable material have been
introduced into the fabric, the first face can be heated,
e.g. using heated air, and the heat will cause the fibres
to contract sufficiently to close the pores enough as to
substantially prevent the particles of settable materials
from escaping. Such fibres that shrink when heated include
the majority of thermoplastic fibres for example
polypropylene. The method of heating fibres to cause
shrinkage described above may also have an advantage in
compacting the settable material especially if such heat
shrinkable fibres are also used to form the second face
and/or the pile yarns.
The second face is preferably substantially impervious to
the settable material so that the settable material does
not fall through the second face when added through the
first face. However, in order to assist in the penetration
of liquid into the space, the second face is preferably
porous to the liquid applied to set the material. Thus,
the second face preferably includes pores having a size
allowing the liquid to penetrate but not allowing material
particles to pass through. If nevertheless the second
sheet has pores that are too large to retain the material
within the space, it is possible to prevent the material
falling out through the second face using any of the
measures discussed above.
As already mentioned, the second and in some cases the
first face of the fabric may be such that the liquid can
penetrate into the space through the faces to contact the
settable powder material within the space. Such liquid
penetration can take place either by including pores
within the face (as discussed above) and/or by making the
yarns of the first and second faces of a material that can
be wetted by the liquid concerned and therefore the liquid
will be wicked through the first and second faces to come
into contact with the settable material within the fabric.
Furthermore, capillary action between fibres within the
first and second faces can assist in providing liquid to
the settable material.
Suitable materials for use in forming the first and second
faces include:
polypropylene, which is the preferred material to use when
the settable material includes cement, as it has excellent
chemical resistance to alkaline conditions;
coated glass fibres, which can provide reinforcement to
the set material;
polyethylene;
PVC fibres, which have the advantage of being relatively
easy to bond using chemical or thermal bonding.
A mixture of fibres can be used.
The length of the pile yarns controls the spacing between
the first and second faces and, as described above, they
must be self-supporting. They should be sufficiently
stiff, i.e. they should be sufficiently resistant to
bending under forces tending to crush the fabric, to
maintain the spacing between the faces when the settable
material has been loaded onto the first face to feed the
material into the fabric. The density of the pile yarns,
i.e. the number of yarns per unit area, is also an
important factor in resisting crushing forces while the
material particles are being added and so maintaining the
spacing between the faces and in restricting the movement
of the material particles once they are trapped between
the upper and lower layers.
It is important, in accordance with the present invention,
that the pile yarn does not divide the space within the
fabric into individual small closed compartments since
such a division would allow cracks to propagate within the
fabric and so reduce the strength of the fabric once the
material has set.
The particle size of the settable material must be
sufficient to allow it to be introduced into the fabric
but it should not be so fine as to fall out of pores in
the first and/or second faces. Especially preferred are
high alumina cements since they provide shorter setting
times than other cements.
The first and second faces and the pile yarn are
preferably part of a spacer fabric, which can be formed
with pores in the first and second faces by the knitting
process used to make it. The second face is preferably
more tightly knitted than the first face so that the pores
in the second face are smaller than in the first face to
allow the settable powder material to be introduced into
the space through the relatively large pores in the first
face and prevent the material falling out of the fabric
through the second face.
The fabric of the present has the advantage that it can be
manufactured and caused to set at will any time later by
the addition of the liquid, e.g. water. The fabric can
therefore be made at one location, transported to another
location, where it is caused to set by the addition of the
liquid, which can be supplied locally, thereby reducing
the bulk that must be transported. The fabric impregnated
with the solid powder will still be flexible and can be
folded or rolled up for transport.
The fabric of the present application has many
applications. Firstly, it can be used to form the cover of
a prefabricated shelter as described in WO 2005/124063.
However, it has wider applications and, for example, can
be used:
to form a track-way for vehicles, pedestrians or animals;
to form a shelter by applying the fabric to a framework;
to make formwork for casting concrete;
to form barriers, e.g. to line tunnels;
to repair or reinforce structures, e.g. roofs;
to form floors or damp proof structures;
to reinforce earth structures, e.g. river banks and
unstable slopes;
to provide flood defences;
to repair existing pipes, including buried water pipes or
to construct new pipes;
to fireproof elements of new or existing structures e.g.
as a fireproof covering or lining for chimneys;
to form a hard surface, reduce dust hazards and contain
fuel spills for aircraft e.g. helicopter landing sites and
runways;
to reinforce sandbag structures and protect them from
ultra violet degradation and damage from the elements such
as wind and ultra violet degradation;
to line ground works and prevent the leaching of chemical
contaminants eg. for land fill or secondary fuel
containment works;
to form a waterproof lining for the containment of water
e.g. pond, canal lining and water storage or septic tanks;
to form permanent awnings or roof structures;
to form artistic or decorative forms, or
to form hulls and superstructure of floating vessels such
as boats or pontoons.
If the settable material is set by the addition of water,
the water can be added deliberately or the fabric can be
put in a place where it will come into contact with water,
e.g. in a watercourse or outside where it can absorb rain.
For example, it is possible to bury the fabric in damp
earth and allow it to absorb water from the earth, thereby
causing the settable material to set.
Once the material has set, the pile yarns also provide
reinforcement to the set material and substantially
increase its strength.
A substantial advantage of the fabric is that the pile
yarns and the fibres of the first and second faces provide
reinforcement to the material once it has set and
accordingly increase the physical properties of the set
material, as discussed more extensively below.
There is theoretically no limit to the thickness of the
fabric, although it will generally be limited by the
manufacturing techniques used to produce it. A typical
thickness would be between 2 and 70 mm, e.g. from 2 to 40
mm, and typically between 4 and 30 mm, e.g. from 4 to 20
mm. One important consideration limiting the thickness of
the material is the ability of the liquid to penetrate
through the interior of the settable material before the
outer portions of the settable material is set. A further
limitation on the thickness comes from the increased
weight of the fabric with increased thickness and if it is
too thick, the faces may not be able to support the weight
of the settable material within the fabric.
BRIEF
DESCRIPTION OF DRAWINGS
There
will now be described, by way of example only, a fabric
material in accordance with the present invention, by
reference to the accompanying drawings in which:
FIG.
1 is a cross sectional view through a spacer fabric;
FIG.
2 is a diagrammatic illustration of the fabric; and
FIG.
3 is a graph showing the strength of the fabric under a
load.
DETAILED
DESCRIPTION OF THE BEST MODE FOR PUTTING THE INVENTION
INTO OPERATION
Referring to the accompanying drawings, FIG. 1 shows a
knitted spacer fabric having a tightly knitted bottom face
layer 10, a more loosely knitted upper face layer 12 and
pile yarns 14 extending across the space 16 between the
lower and upper face layers 10, 12. The spacer fabric is
made of knitted polyethylene and is commercially available
from Scott & Fyfe as 5 mm spacer fabric.
Settable material, e.g. cement, is introduced into the
fabric through pores 20 in the open-knit upper face layer
12. The pores 20 arise through the knitting process during
manufacture of the spacer fabric. The cement can be placed
on the spacer fabric and will fall through pores 20 into
space 16. The penetration through the pores 20 can be
assisted through vibration. It is preferred that the whole
of the space 16 is filled with cement in this way.
Vibration also has the advantage of settling the cement
within the space 16 to prevent voids or air pockets being
formed. Additionally, the settable material can be drawn
into space 16 by resting the spacer fabric on a porous
surface and applying suction through the porous surface to
form a pressure drop across the spacer fabric, which
assists in the compaction of the settable material within
the spacer fabric and reduces the instances and size of
residual voids and air pockets. Additionally, compaction
of the settable material within the space 16 may be
further increased by vibration of a heavy plate resting on
the spacer fabric containing the settable material.
The bottom face 10 has a relatively tight knitted
structure and the size of the pores in the bottom face are
smaller than in the upper face layer such that the pores
are sufficiently small to prevent substantial amounts of
the cement from falling out.
After the material has been introduced into the space 16,
the upper face layer 12 is sealed by the application of a
thin coat of PVC paste which is then cured by heating the
surface.
Water can penetrate into the fabric through the pores in
the bottom face 10; hydration of the cement is aided by
the pile yarns 14, which can wick water into the interior
of the fabric.
The fabric including the settable material within the
space 16 is flexible and can be formed to shape prior to
the introduction of liquid to set the material within the
space.
The long fibres 18, together with the shorter fibres in
the fabric, provide reinforcement to the material, when
set and prevent crack propagation.
Example
1
Three test pieces of fabric in accordance with the present
invention having a surface area of 725 mm<2 >were
produced by introducing high alumina cement into a spacer
fabric, the spacer fabric was a polyethylene knitted
fabric manufactured by Scott and Fyfe being 5 mm thick.
The fabric was then sprayed with water and allowed to set
for 4 days. The test pieces were then subjected to the
following test: the test pieces were each placed in an
Instron—5584-52536 Universal Materials Testing Machine
having a movable anvil that can apply compressive forces
to the test piece. Each test pieces was loaded so that the
anvil acts perpendicularly to the knitted faces. A load
cell measures the compressive load and the displacement of
the anvil. The compressive load was progressively
increased until the test piece failed and the load exerted
on the test piece and the displacement of the anvil at
failure were logged by a computer connected to the
machine. The procedure was repeated four times using
separate samples.
The results are shown in FIG. 2, from which can be seen
that the four test pieces of fabric material in accordance
with the present invention failed at a consistently high
compressive load and that once initial failure had
occurred, when cracking could be observed in the samples,
the samples did not fail catastrophically but continued to
support a consistently high compressive load as the
displacement was increased progressively.
SG196860
IMPREGNATED
CLOTH
Quick-setting
and rapid-hardening cement matrix for concrete canvas
system and use method there of
CN103360027