Note: Descriptions are shown in the official language in which they were submitted.
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RBP File No. 5590-001
Title Noise Ab~tement Element
FIELD OF THE IMV~TION
This invention relates to noise abatement
elements and barriers.
BACKGE~OUND OF TIIE INVENTION
Noise abatement barriers are frequently
provided, for example, along the edges of highways to
protect adjacent areas from traffic noise. Such barriers
come in varied forms and are often abricated from, for
example, concrete or corrugated metal. However these forms
of barriers tend to reflect sound rather than absorb it,
such that the barriers may simply redirect the trafic
noise towards the opposite side of the highwa~. Concrete
barriers are o~ten formed o a plurality o concrete slabs
which are located between supporting uprights and mounted
on top of one another to form walls. Although
construction of the barrier may only requlre positioning
and anchoring of the supporting uprights and location of
the prefabricated slabs between the uprights, the weight
of the slabs necessitates the provision of heavy moving
equipment for the transporting and positioning the slabs.
Although metal barriers are generally less substantial
than concrete barriers and may be lighter in weight,
mat~rial costs for metal barriers are relatively high.
Various other means or providing noise
abatement barriers have been proposed, including those
disclosed in the below listed U.S. patents:
No. 3,948l009 issued April 6, 1976 to Bernhard
No. 4,566,558 issued January ~8, 1986 to LinX,
Jr. et al
No. 4,643,271 issued Feb. 17, 1987 to Coburn
No. 3,698,993 issued Oct. 17, 1976 to Rauh
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No. 4,1~3,495 issued March 13, 1979 to Hintæ
No. 3,~61,682 issued June 8, 1976 to Dausch et
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Bernhard describes sound a insulating wall
comprising elements formed of rubber shavings with a resin
binder. A number of different examples of element
composition are described, including one in which the
resin binder is cellular and has a predominantly closed
cell structure, which is described as having good sound
reflective qualities, and further examples in which the
space between the rubber shavings is only partly filled
with binder, and which may be filled with open cell foam
waste, to provide high sound absorbtion. For this form of
element, the side facing away from the sound source is
provided with a closa textured covering for reflecting
back sound waves which have penetrated through the
element. The side of the element facing the sound source
may be provided with an absorbtion layer of stone wool or
soft foam material and this is covered with a synthetic
fiber fleece. The patent also discloses the use of
reinforcing elements which are located between the boards,
and the possibility of providing mechanical reinforcements
such as wire inserts in the boards is also mentioned.
The edges of the boards may be profiled so that,
when several boards are placed one upon the other, they
en~age with each other by the corresponding profiles.
Link, Jr. et al. describes a noise barrier
formed of a slab of plastic foam sandwiched between ou~er
sheets of plastic. The sheet of plastic facing the sound
source is perforated over a number of recesses formed in
the plastic foam, the recesses being filled with a sound
absorbing material such as rubber granules. Reinforcing
members are provided in the form of channel members
embedded in the faces o-f the plastic foam.
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Dausch et al. describes a sound absorbing wall
element formed of two layers, one layer comprising
shredded rubber and a binder and a second backing layer
comprising loose rubber shreds supported in a sheet metal
frame.
Loose shredded rubber is also used as a sound
absorbing material in Hintz. The patent discloses a sound
absorbing panel formed of two sheets of corrugated sheet
metal, the front sheet being perforated. The shredded
rubber is held in a space between the rear sheet and a
wire mesh located between the sheets.
A somewhat different form of sound barrier is
described in the Coburn patent, which discloses the use
of gabions, a gabion being a wire cage which is normally
filled with rocks for use in erosion control and the like.
As disclosed by the patent, a sound barrier may be form~d
of a stack of gabions, the gabions closest to the highway
being filled with shredded tires and the reaxmost gabions
being filled with crushed stone and sound absorbing
material such as shredded polystyrene foam.
Rauh describes a sound deadening sheet material
formed of a foamed, closed shell sheet with cells of
various sizes spaced throughout the sheet and discrete
small particles of high specific gravity distributed
through the sheet. It is suggested tha~ the discrete
particles be formed of metallic oxide. One side of the
sheet is a smooth skin and on the other side of the sheet
the skin is torn to provide a fibre-like surface to
partially dissipate the initial sound waves striking the
surface.
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SUMNARY OF TEE INVENTION
According to a first embodiment of the present
invention ~here is provided a noise abatement element
formed of a granular material and a binder and including
a relatively rigid reinforcing member located within the
element.
Pref~rably, the granular material and binder are
in the form of granular rubber and a polymer which form a
flexible, sound absorbent material. The reinforciny
member assists in providing the element with additional
rigidity. Preferably also, the reinforcing member extends
over the length of the element and is in the form of an I-
shaped beam of laminated wood.
According to a second aspect of the present
invention there is provided a noise abatement barrier
comprising at least two spaced uprights and a plurality
of elongate noise abating elements extending between the
uprights and located one on top of another to form a wall.
Each element is formed of a crumb rubber and binder mix
and includes a relatively rigid reinforcing member located
wit~lin the element.
According to a third aspect of the present
invention there is provided a method of producing a noise
abatement element comprising the steps: providing a mix
of granular material and a binder; providing a mould
de~ining an elongate form; locating a relatively rigid
elongate reinforcing member in the mould; adding said mix
to the mould; curing the binder to solidify the mix in the
mould; and removing the solidified mix from the mould.
30 BRI~F DESCRIPTION OF T~IE DRAWINGS
These and other aspects of the present invention
will now be described, by way of example, with reference
to the accompanying drawings, in which:
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Figure 1 is a front elevation o~ a noise
abatement barrier in accordance with a preferred
embodiment of khe present inven~ion,
Figure 2 is a top plan view of the noise
abatement barrier of Figure l;
Figure 3 is a sectional view on line 3-3 of
Figure 2, showing a section ~f a noise abatemant element
of the barrier of Figuxe 2; and
Figure 4 is a somewhat simplified illustration
of the method of producing the noise abatement element of
Figure 3.
DETAILED DESCRIPTION OF DRAWINGS
Reference is first made to Figures 1 and 2 of
the drawings, which show a portion of a noise barrier 10
in accordance with a preferred embodiment of the present
invention. The barrier 10 comprises a plurality of spaced
uprights 12, 14 with a plurality of noise abating elements
16 extending therebetween and located one on top of
another to form a wall. The uprights 12, 14 are in the
form of I-beams which are securely mounted in the qround.
Typically, the bases of the upright~ 12, 14 will be set in
concrete or the like. The inwardly directed channels 18,
20 provided by the uprights 12, 14 receive the ends of the
elements, the central web portions 19, 21 of the uprights
being spaced apart a distance slightly longer than the
length of the elements such that the elements may be
located between the uprights~ The uprights 12, 14 and the
elements 16 are sized such that the ends of the elements
are a snug fit in the channels 18, 20.
Only two uprights are shown in Figures 1 and 2,
though a typical barrier would comprise a large number of
spaced uprights and elements.
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The elements 16 are generally elongate in form
and comprise a mix of recycled crumb rubber and a binding
agent. The crumb rubber is preferably formed by shredding
discarded vehicle tires. The binding agent is preferably
a polymer.
The resulting composite is fairly flexible and
in order to provide the element 16 with some rigidity,
each element contains a reinforcing element, in the form
of a length of laminated wood 2~ of an I~cross-section
which extends over the length of each element. The length
of wood 22 provides sufficient rigidity to enable the
elements to be easily handled and transported.
The element also contains a fire retardent and
may contain colour pigment, depending on the desired
colour of the element.
The elements 16 may be of plain rectangular
cross-section, shown in Figure 3 of the drawings, but may
also be provided with other cross-sections, for example,
the element top surface may be provided with a tongue and
the bottom surface provided with a corresponding groove
such that adjacent elements may interlock to provide a
more effecti~e sound isolating interface between adjacent
elements and also to add to the structural strength of the
wall formed by the elements.
The method o~ producing the sound elements will
now be described, with reference to Figure 4 of the
drawings.
The elements are formed by first mixing a
quantity of rubber crumbs with a prepolymer. The mix 40
is then poured i.nto a metal mould 42 which defines an
elongate form identical to the desired form of the
element. ~ length of wood 22 is mounted in the mould such
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that the crumb and prepolymer mix encapsulates the wood.
The prepolymer is then cured, the curing process being
controlled by heating the mould 42 using suitable heating
means ~4, and applying pressure to the mix by providing
the mould 42 with a moveable wall 46, the pressure force
being provided by means of a hydraulic actuator 48, to
bind the granular material and the wood to form an
integral ~lement, which may then ~e removed from the
mould.
The components of the mix and the dimensions of
~he element may be varied to provide elements suitable for
various purposes. The crumb rubber, as mentioned above,
is preferably formed of shredded vehicle tires, the crumbs
preferably having a diameter of approximatel~ one quarter
of an inch. If the crumbs are substantially similar in
diameter, the resulting element will be less dense than an
element formed with crumbs of more varied sizes. The
density of the element may also be increased by increasing
the heat and pressure used during curing of the binder.
The binder is prefer~bly a polyurethane based
material, such as FLEXILON 40:2 (Trade-Mark), a solvent
free diphenyl meth~ne di-isoyanate polyether prepolymer
(MDI) available from Rosehill P~lymers Ltd., of Sowerby
Bridge, England. The binder is preferably added to the
crumb rubber in ratio of 10% by weight to the total weight
of crumb rubber. The fire retardent, and the colour
pigment, where present, are also mixed with the binder.
For the preferred element composition a flame retardent
chemical such as Fyrol (Trade-Mark) PCF, a tri (B-
chloroisopropyl) phosphate 2-chloro-1-propenol, phosphate
(3:1), as available from Stauffer Chemical Company of
Westport, Connecticut, U.S.A. may be used.
Although the dimensions of elements may vary it
is preferable to have the element and reinforcing member
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dimensions of generally similar proportions. One example
of an element is set out below:
Element width (A) = 5 3/4"
Element depth (B) = 10"
Reinforcing member overall depth (C) = 9"
Reinforcing member flange width (D) = 1 3/4~
Reinforcing member flange thickness (E) = 1 1/2"
Reinforcing member web thickness (F) = 3/4~
The resultin~ elements are relatively light, and
thus may be transported and installed with minimal need
for heavy equipment/ are substantially weatherproof and
have good sound reflective and absorbtion properties.
Also, the use of relatively inexpensive materials to form
the elements and the savings in transportation and
installation when compared to conventional barriers,
allows for the provision of barriers in accordance with
the present invention at advant:ageous cost. In addition,
use of resilient material ~or much of the element allows
the element to absorb minor bumps without damage, and if,
for example, the bump was from a vehicle, the vehicle
would likely sustain only minor damage, if any. In more
violent collisions the elements will give-way and the
reinforcing mamber break. This would likely result in
reduced passenger injury and vehicle damage when compared
~o a collision with, for example, a rigid concrete noise
bar~rier.
It will be clear to those skilled in the art
that the present invention is not limited to the
particular uses described above and further that various
modifications and improvements may be made to the
invention without departin~ from the scope of the present
invention.
