EP0527115B1

EP0527115B1 - A soundproofing and deadening modular board unit for forming antinoise barriers

Info

Publication number: EP0527115B1
Application number: EP92830415A
Authority: EP
Inventors: Giovanni C/O Insokell S.P.A. Rinaldi
Original assignee: INSOKELL SpA
Current assignee: INSOKELL SpA
Priority date: 1991-08-05
Filing date: 1992-07-27
Publication date: 1995-09-06
Anticipated expiration: 2012-07-27
Also published as: DE69204601D1; IT1249829B; ITRM910597A1; EP0527115A1; ITRM910597A0; ATE127560T1

Abstract

A soundproofing and sound-deadening board modular unit for antinoise barriers, said unit comprising a first metallic hull 2B which is exposed to the source of noise, a second metallic hull (3B) performing the function of a cover or lid, and a sound-deadening member of tight-seal, modular type, which is realized with a first layer (7B) of an impermeable film, of a polyurethane -type membrane, a second layer (8B) consisting of a high-density sound-deadening separation wall, and a third layer (9B) consisting of a low-density mattress, said first, second and third layer, being reciprocally joined by means of a hot-pressing process, and said sound-deadening board being fastened by a fixed joint within a cavity that is defined at the points corresponding to the upper and lower edges of said first and said second metallic hull. <IMAGE>

Description

This invention relates to a soundproofing and deadening board modular unit for antinoise barriers.
More particularly, this invention belongs in the framework of antinoise barrier technologies which are particularly suitable for employment as soundproofing members on highways, freeways, railways and the like.
More generally, such types of barriers are made up of three fundamental members such as the modular boards making up the soundproofing shield, the supporting uprights consisting of steel structural work, and the foundation structures.
As regards the modular boards employed for forming anti-noise barriers, two distinct categories of said boards are employed in the present-day technology, such categories being divided according to the acoustic action exerted by the same.
In particular, a distinction can be considered between:

a) soundproofing board units, and
b) soundproofing/sound-deadening board units.

The latter exert a stronger action as in addition to interfere on the diffusion in the acoustic field preventing with their soundproofing characteristics it from propagating downstream of the soundproofing barrier, also realize a deadening effect of acoustic energy on the side of the barrier itself which is exposed to the noise source, which might be for instance the road or the railway traffic.
In the category of soundproofing/sound-deadening board units known at present, two different construction procedures can be distinguished for the realization of the same, i.e. the box-type boards or the boards made up of an outer structure consisting of a metal sheet (steel or aluminum alloys) or plastic or composite materials (ABS, plastic reinforced with glass fibres) or a combination of the same, and of a mattress or a plate of a sound-deadening material put inside the structure, and the so-called "sandwich" type boards, or boards built by mechanical coupling through gluing operations of a perfectly soundproofing member with a sound-deadening layer made up of plates of a fibrous or pit-bearing material.
The types of solution which are known at present and which make use of the box-type boards, while show the advantage of being realizable with materials already widely employed in other branches of the technical activities and hence widely reliable, with the use of quite simple plants, on the other side are also affected by considerable drawbacks as regards durability and reliability.
Such drawbacks are connected to the sound-deadening characteristics of the board itself; in the case of classical boards, such function is exerted by a layer of a homogeneous fibrous and porous material (mineral wool) which fills the gap between the two hulls of the structure.
The sound-deadening property of the material becomes degraded in time due to the effect of water and dust thrown against the boards by vehicles in transit.
The material so thrown against the board become absorbed by the surface of the porous material on the side facing the drilled hull and plug such surface, and in the long time the material projected lowers the sound-deadening properties of the board.
A further risk of degradation consists in vibrations induced in the board itself by wind forces and by the passing vehicles, which vibrations favour in time the flaking off of the porous material.
Among others solutions in the CH-672932 of Montana Stahl AG is described a sound proofing and deadening board for the absorption of low frequency sounds having two separate and supported different density sound-deadening layers housed within an external metallic structure. Said board however shows the disadvantage of a rapid deterioration of the sound-deadening layers also in view of the non water proof quality of the same.
A solution intended for improving the protection degree of the box-type structure, so reducing the penetration of liquids, is suggested in the patent application No. 47756-A/85 in the name of Hans Biegler. A structural member is disclosed in said patent application, said member being intended for a protective wall and having a metal hull exposed to the noise sources and made up of an aluminum alloy, endowed with slits staggered with respect to each other and realized by shearing and drawing in the shape of a weathered roof so as to allow the sound wave to pass and the successive absorption of said wave to occur by the action of the porous mattress, but lowering at the same time the penetration of liquids and other atmospheric agents that cause the degradation of the good characteristics of the mattress itself.
Such solution gives remarkable advantages with respect to other solutions known at present (for instance, circular or rectangular holes), but it does not solve definitively the problem connected to the durability of the mattress itself.
Accordingly, it is evident that there is the need for soundproofing/sound-deadening boards that are capable of warranting the continuity of the design performances in time, under any conditions of employment and service, and that gives at the same time a performance with adaptation to the most different conditions of design, with simple assembling operations and low realization costs.
Moreover, it is also evident that there is the need for an innovative solution of modular type that allows the sound-deadening power of the boards as well as the soundproofing power of the same to be increased, keeping the configuration of the metallic hulls and the thickness of the same unchanged.
In order to satisfy such need, the realization of a self-supporting multilayer composite for a soundproofing and sound-deadening board for antinoise barriers is proposed according to this invention in order to increase the sound-deadening power of the board itself, which realization removes the impregnation effects and exploits the principle of absorption of porous and waterproof membranes to realize the maximum absorption of the frequency range of the maximum sound emission of vehicles, and, in order to increase the soundproofing power of the board, it is proposed according to this invention to provide a layer made up of heavy waterproof rolled sections and to stiffen the outer hull that closes the board itself.
Accordingly, it is proposed in this invention to realize a soundproofing and sound-deadening board, inside which a self-supporting multilayer composite is provided which is made up of layers of a material having differentiated densities, such layers being joined together by means of a pressing process and in which, in order to improve the soundproofing function, the presence is provided of a further layer made up of a heavy material, which is connected in its turn to said multilayer structure having differentiated densities, capable of giving also rise to a stiffening of the board itself without giving rise to any size changes at the front and back positions of the metal sheet.
In particular, it is proposed in this invention to realize, as a sound-deadening structure, a multilayer mattress, closed by an outer membrane and realized with a plastic material film which is capable of preventing liquids from penetrating and to obtain protection against atmospheric agents to the whole system, said multilayer mattress being provided with at least two porous layers of different densities, the layer having the highest density facing toward the noise source.
Thus, by closing a set of layers of different densities inside the membrane, a sound-deadening system is obtained which realizes the best impedance behaviour for the sound wave impinging on the same, in the frequency range of interest and, as a consequence, a high absorption coefficient over a wide frequency range, while the waterproof membrane forms with the sound-deadening system behind it a resonator whose resonance frequency is in the middle of the frequency range of interest.
The mathematical model for visualizing the acoustic properties of said multilayer composite is realized by means of the formalism of the transfer matrix, employing the characteristics of the single layers as parameters.
In particular, the characteristics of the layers considered in order to obtain the mathematical model capable of supplying the necessary sound-deadening and sound proofing values are the following:

a) a heavy waterproof layer
weight per unit surface
b) an air layer
thickness
elastic modulus
c) a low-density porous layer
density
thickness
elastic moduli of the frame and of air resistance to the passage of air porosity
d) high-density porous layers
weight per unit surface resistance to the passage of air.

in order to obtain various values of sound-deadening of the modular board, various combinations of the layers menò tioned above can be realized, also aiming at obtaining adaptation to the various size characteristics of the containing structure.
Again according to this invention,it is suggested to realize the soundproofing/sound-deadening multilayer composite in such a way as to be easily put inside the box-type member made up of metal sheet and containing the structure, and to be easily fixed to such member by means of a fixed joint, avoiding in that way any type of further fixing members because such members form discontinuity points within the material itself that contribute to create weakness points which are more easily attacked by atmospheric agents with the result of a reduced reliability and durability of the material itself.
Moreover, again according to this invention, the realization of a soundproofing/sound-deadening board is proposed, said board containing a multilayer composite of thin thickness, with the consequent increase in the thickness of the air space inside the box-type board.
Finally, according to this invention the proposal is put forward of shaping the profile of the outer metallic hull and of the inner metallic hull in such a way as to have the possibility of fixing to the same by means of fixed-joints both the multilayer composite made up of the set of layers having different densities with a sound-deadening function, and the multilayer structure made up of the layers having different densities and of the inner soundproofing layer.
Accordingly, it is a specific object of this invention a self-supporting modular, soundproofing and sound-deadening board for antinoise barriers, said board comprising a first metallic hull which is suitable to be exposed to a noise source, a second metallic hull performing the function of a cover, a soundproofing and sound-deadening multilayer composite which is located inside said first and second hulls, wherein said outer hull which is exposed to the noise source has, at the points corresponding to said surface, slits disposed in staggered way covered by projecting portions obtained in said first metallic hull for decreasing the seepage of water and other atmospheric agents, said board being characterised in that said sound-deadening multilayer composite is made up of a first layer exposed to the source of noise made up of a light waterproof membrane impermeable to liquids and atmospheric agents, a second layer made up of a high density porous membrane endowed with a high resistance to the air passage, and of a third layer of a low-density porous material wherein said first, second and third layers having been joined by means of a hot-pressing procedure, wherein said first layer of impermeable membrane is fastened to the edges of said second and said third layer so as to ensure the impermeable properties of the same, wherein said outer metallic hull exposed to the source of noise has, at the points corresponding to the upper and lower edges a first recess and a second projecting portion defining a longitudinal cavity, and wherein said metallic hull having the function of a cover has, at the points corresponding to the upper and the lower edges, a compound profile having a first end portion substantially parallel to but spaced from said outer surface of said first metallic hull, a second end portion inclined with respect to the first end portion and a third end portion at the outer end of the second end portion which is substantially parallel to the first end portion, wherein said first second and third end portions define, with the inner surface of said first hull, a cavity for the housing and fastening of said sound-deadening multilayer composite.
According to a preferred embodiment, said first layer of said sound-deadening multilayer composite is fastened to the front surface of said second layer in a frontal way.
An alternative embodiment of this invention provides a self-supporting, soundproofing and sound-deadening modular board for antinoise barriers, said board comprising a first metallic hull exposed to the source of noise, a second metallic hull having the function of a cover, a soundproofing, sound-deadening multilayer composite housed inside said first and second hull, wherein said outer hull which is exposed to the source of noise has, at the points corresponding to said surface, slits disposed in a staggered pattern covered by projecting portions obtained in said first metallic hull for decreasing the seepage of water and of other atmospheric agents, said board being characterised in that said soundproofing and sound-deadening multilayer composite is made up of a first layer exposed to the source of noise and of an impermeable light membrane, a second layer made up of a high-density porous membrane, a third layer of a low-density porous material, and a fourth layer comprised of a heavy impermeable rolled sheet based on bituminous or elastomeric material that exerts a stiffening action, having been fixed to the composite of said first, second and third layer by a pressing operation.
According to a preferred embodiment, said fourth layer soundproofing multilayer composite is applied mechanically or glued to said second outer metallic hull having the function of a cover.
Again according to this invention, said first layer of said sound-deadening, soundproofing multilayer composite is made up of a membrane consisting of an impermeable fabric or an impermeable film based on a polyurethane, polyester, polyamide plastic material, or an aluminium film weighing between 20 and 60 g/m², and preferably 40 g/m².
Moreover, advantageously, said second layer of said soundproofing/sound-deadenint modular composite consisting of said high-density porous membrane is made up of fibrous tufts of the TACA-ABX type and pressed, or of mineral wool, or of a pierced plastic filme or fabric, and it should have a resistance to the flow of air of optimized value as a function of the characteristics of the third layer, the preferred values oscillating between 800 and 1,200 Rayls/m.
Again according to this invention, it is suggested to realize said third layer of said sound-deadening/soundproofing modular composite with a low-density porous material, as for instance TACA-ABX fibrous tufts, or mineral wool or open-cell foams as for instance polyurethane or melamine foamed material, with thicknesses ranging from 2 to 5 cm and with a specific resistance to the flow of air between 10,000 and 30,000 Rayls/m.
Finally, again according to this invention, said fourth layer will be realized advantageously with heavy rolled material based on bituminous or rubber matter, whose weight ranges from 4 to 10 kg/m². In order to increase the soundproofin power and the sound-deadening effect of the complete board, stiffening materials or inserts will be put into the layer, in case the bow-type member having the function of a cover is to be strengthened.
This invention will be disclosed in the following according to some preferred embodiments of the same with particular reference to the figures of the enclosed drawings, wherein:

Figure 1 shows a cross-sectional vertical view of the soundproofing and sound-deadening board according to the present invention, which shows a three-layer sound-deadening multilayer composite ;
Figure 2 represents a cross-sectional vertical view of the soundproofing and sound-deadening board that has a four-layer soundproofing and sound-deadening multilayer composite ;
Figure 3 represents a cross-sectional vertical view of the board that shows a four-layer soundproofing and sound-deadening multilayer composite with an air jacket;
Figure 4 shows a cross-sectional vertical view of the metallic profiles making up the hull; and
Figure 5 shows a front view of the metallic hull which is exposed to the source of noise.

As can be observed in Figure 1, the board 1 is made up schematically of a metallic hull 2 which is exposed to the source of noise and is illustrated in a more detailed way in Figure 5, and it is also made up of a back metallic hull 3 performing the function of a cover, said board being made up of a multilayer modular composite as well, said structure consisting of sound-deadening materials having differentiated densities.
Such multilayer composite 4 is housed and positioned in a fixed way between the hulls 2 and 3 so as not to require any further member for being fastened and so as not to reduce its own structural integrity.
The metallic hull 2 is suitable to be exposed to the source of noise has a set of slits 5 at the points corresponding to such surface, said slits being obtained by drawing in the metal sheet that makes up the hull itself, so as to reduce the seepage of water and of other atmospheric agents into the board.
Again with reference to Figure 1, it can be observed that the sound-deadening multilayer composite is made up of three different layers.
In particular, the first layer 7 is made up of an impermeable, liquid-tight film, preferably made up of a polyurethane, a polyester or a polyamide material or of an aluminum film whose weight ranges between 30 and 60 g/m², preferably 40 g/m², said film being fastened during a process of hot-gluing to the successive second and third layers at the points corresponding to the longitudinal edges.
On the contrary, said layer 7 is glued at some points to adjacent layer.
Such layer, which is labelled with the reference numeral 8 in Figure 1, is made up of a high-density porous membrane, preferably in the shape of a molded or pressed mattress of the TACA-ABX type or made up of a mineral fibre fabric or of plastic materials or a pierced film of a plastic material.
Preferably, such layer has a thickness of about 3 mm, a weight ranging from 1,000-15,000 g/m² and a resistance to the flow of air of 800-1,200 Rayls.
On the contrary, the third layer has a lower value of density and is made up of TACA-ABX or of mineral wool or of an open-cell foamed material and its thickness varies in the range between 20 and 50 mm.
As already mentioned above, the layers 7, 8 and 9 are joined by means of a hot-pressing procedure.
According to a preferred embodiment of the board of this invention as shown in Figure 1 which is illustrated in Figure 2, it is possible to observe in the latter figure that said multilayer sound-deadening structure is made up also of a further layer 10 in addition to the layers 7A, 8A and 9A realized with the same materials as those already illustrated for the board 1.
Such configuration, completed with a layer for making the containment cover heavier and sound-deadening, is employed in the cases in which a high soundproofing power is required.
The layer 10 which has a tray-like shaping, and inside which the low-density layer 9A is housed, is made up of heavy impermeable rolled materials consisting of a plastic or a metallic material of thickness ranging from 2 mm to 10 mm and having weights ranging from 5 to 15 kg/m².
Such layer is fastened by hot gluing to the layers 7A, 8A and 9A and is fastened mechanically or glued to the inner surface of the metallic hull 3A, so as to supply the same with further stiffness and so as to increase the soundproofing effect.
Figure 3 shows a further kind of embodiment of the board of Figure 2 in which the low-density layer 9B is partially substituted with an air gap or jacket and in which the layer 10B is fastened mechanically to the hull 3B in order to perform its stiffening function.
Figure 4 represents in cross-sectional vertical view and in a non-assembled position, the profile of the metallic hull which is exposed to the noise source 2 and of the outer hull 3.
It can be observed that the extreme positions 11 of the hull, which are delimited within the circle, show a portion 12 which, when the hulls 2 and 3 are assembled together, adheres to the inner part of the hull 2, because it is parallel to the same, and they also show a curvilinear and receding portion 13.
This last portion, together with the portion 12 and also together with the inner portion of the metallic hull 2 which is exposed to the source of noise, delimits the cavity in which the sound-deadening multilayer structure 4 goes according to the design, so as to become fastened by a fixed-joint and keeping so fastened in the position delimited by said cavity and without the need for particular fastening systems.
The metallic hulls 2 and 3 are fastened reciprocally on the contrary at the points corresponding to the holes 13.
Such fixed-joint type of fastening system so designed allows, once the hull 2 is available, the sound-deadening multilayer structure 4 to be positioned on the same and then allows the assembling with the hull 3 to be completed together with the fastening of said pull with the hull 2, so fastening in the correct position the structure 4 by means of a fixed joint.
In addition, it is to be observed that the shaping of the two hulls 2 and 3 is so realized as to allow a number of boards to be assembled in a set, on steel-structure work, in order to build continuous antinoise barriers.

EXAMPLE

Sequence of layers described starting from the noise source side:

1st layer

An impermeable membrane made up of a waterproof or fluid impermeable fabric or of a film consisting of a plastic material: a polyurethane, a polyamide or a polyester and so on, or an aluminum film.
In a principle and protection function of the porous layers.
From the acoustical standpoint, together with the sound-deadening system consisting of the layers II and III , the membrane forms a resonator whose sound-deadening characteristics are linked to the phenomenon of resonance, the maximum value of the sound-deadening coefficient being obtainable at the resonance frequency of the system: $F = 500 x [K/(d x M)] 1/2 (Hz)$
wherein:

K =: elastic modulus of the sound-deadening system behind the membrane (layers II and III) (N/cm²)
d =: thickness of the sound-deadening system (cm)
M =: mass of the impermeable membrane (kg/m²)

The optimal weight can vary between 20 and 60 g/m² as a function of the thickness of the layers II and III.
The membrane is fastened all along the perimeter, and just partially on the surface of the underlying layers; glue lines or points at distances not lower than 5 cm are acceptable.
The membrane covers accurately the perimeter of all underlying porous layers in order to avoid the absorption of liquid matter due to capillarity phenomena.

2nd layer

A high-density porous membrane weighing 1:1.5 kg/m², and whose optimal resistance s to the flow of air is given by: $s = (R x d)/3 (Rayls)$
wherein:

R =: specific resistance to the flow of air of the low-density porous material (III layer) (Rayls/m)
d =: thickness of the low-density porous material (III layer) (mm)

3rd layer

A low-density porous mattress (mineral wool or TACA ABX or an open-cell foamed material), having the following optimal characteristics:

thickness variable as a function of the thickness of the containing board; the thicker the thickness of the layer, the higher the sound-deadening coefficient of the completed board, a thickness of 5 cm being provided for the preferential configuration
resistance to air flow: R = 10,000-30,000 Rayls/m
elastic modulus of the frame: less than 1 N/m²

The function of the layers II and III is that of supplying a sound-deadening system having a sound-deadening coefficient higher than 0.7 in the frequency range in which the vehicle noise is maximum.

4th layer

A heavy rolled sheet (based on a bituminous, or an elastomeric or a fibrous material) of thickness variable between 2 and 10 mm, whose functions are:

making the structure heavier, on the side opposite to the noise source, in order to increase the soundproofing power of the completed board
increasing the sound-deadening power of the structure in order to reduce the vibrations induced by the wind thrust or by the vehicles passing by
making possibly the whole structure stiffer.

This invention has been disclosed just for illustrative and not for limitative purposes according to some preferred embodiments of the same, but it is to be understood that modifications and/or changes can be introduced by those who are skilled in the art without departing from the scope of the invention for which a priority right is claimed.

Claims

A soundproofing, sound-deadening self-supporting modular board (1) for antinoise barriers, said board (1) comprising a first metallic hull (2) suitable for being exposed to a noise source, a second metallic hull (3) performing the function of a cover or lid, a soundproofing and sound-deadening multilayer composite (4) housed inside said first (2) and second hull (3), wherein said first hull (2) exposed to the noise source has, at the points corresponding to said surface, a set of staggered slits (5) which are protected by projecting fins, said fins being obtained in the metal sheet itself in order to decrease the seepage of water and of the atmospheric agents, said board (1) being characterised in that said sound-deadening multilayer composite is made up of a first layer (7) exposed to the source of noise realised by a light, liquid impermeable membrane which also resists the seepage of atmospheric agents, a second layer (8) made up of a high-density porous membrane showing a high resistance to air flow, and of a third layer (9) of a porous, low-density material, wherein said first (7), second (8) and third layer (9) are coupled together having been joined by means of a hot-pressing procedure, wherein said first layer (7) of impermeable membrane is fastened to the edges of said second (8) and said third layer (9) so as to assure the impermeable character of the same, wherein said first metallic hull (2) exposed to the source of noise has, at the points corresponding to the upper and lower edges a first recess and a second projecting portion defining a longitudinal cavity, and wherein said metallic hull (3) having the function of a cover or lid has, at the points corresponding to the upper and lower edges (11) a compound profile having a first end portion (12) substantially parallel to but spaced from said outer surface of said first metallic hull (2), a second end portion (13) inclined with respect to the first end portion and a third end portion at the outer end of said second end portion which is substantially parallel to the first end portion (12), wherein said first (12) second (13) and third end portions define, with the inner surface of said first hull (2), a cavity for the housing and fastening of said sound-deadening multilayer composite (4).
A soundproofing, sound-deadening self-supporting modular board (1) for antinoise barriers, said board (1) comprising a first metallic hull (2) suitable for being exposed to a noise source, a second metallic hull (3) performing the function of a cover or a lid, a sound proofing, sound-deadening multylayer composite (4) housed inside said first (2) and second hull (3), wherein said outer hull which is exposed to the source of noise has, at the points corresponding to said surface, slits (5) disposed in a staggered pattern covered by projecting portions obtained in said first metallic hull (2) in order to decrease the seepage of water and of other atmospheric agents, said board being characterised in that said soundproofing and sound-deadening multilayer composite (4) is made up of a first layer (7) of high impermeable membrane exposed to the source of noise, a second layer (8) of high density porous membrane; third layer (9) of a low density porous material and a fourth layer (10) comprised of a heavy impermeable rolled sheet of plastic material which has a stiffening function; said fourth layer (10) having been fixed to the composite of said first (7), second (8) and third layer (9) by a pressing operation.
A soundproofing, sound-deadening and self-supporting modular board (1) for antinoise barriers according to claims 1 and 2, said board (1) being characterized in that said first layer (7) of said sound-deadening, soundproofing multilayer composite (4) is made up of a membrane consisting of an impermeable fabric.
A soundproofing, sound-deadening self-supporting modular board (1) for antinoise barriers, according to claims 1 and 2, characterized in that said first layer (7) of said sound-deadening, soundproofing multilayer composite (4) is made up of a powder based on a polyurethane plastic material.
A soundproofing, sound-deadening self-supporting modular board (1) for antinoise barriers according to claims 1 and 2, characterized in that said first layer (7) of said sound-deadening multilayers composite (4) is made up of an aluminium film.
A soundproofing, sound-deadening self-supporting modular board (1) for antinoise barriers according to claims 1 and 2, characterized in that said first layer (7) of said sound-deadening, soundproofing multilayer composite (4) has a weight in the range from 20 to 60 g/m², and preferably of 40 g/m².
A soundproofing, sound-deadening self-supporting modular board (1) for antinoise barriers according to claims 1 and 2, said board being characterized in that said second layer (8) of said sound-deadening, soundproofing multilayer composite (4) consisting of a high-density porous membrane is realized with a pressed fibrous tuft of the TACA ABX type.
A soundproofing, sound-deadening self-supporting modular board (1) for antinoise barriers according to claims 1 and 2, said board being characterized in that said second layer (1) of said sound-deadening, soundproofing multilayer structure (10) consisting of a high-density porous membrane is realized with a pierced fabric.
A soundproofing, sound-deadening self-supporting modular board (1) for antinoise barriers according to claims 1 and 2, said board (1) being characterized in that said second layer (8) of said sound-deadening, soundproofing multilayer composite (4) consisting of a high-density porous membrane shows a resistance to air flow ranging between 800 and 1,200 Rayls, and preferably of 1,000 Rayls.
A soundproofing, sound-deadening self-supporting modular board (1), for antinoise barriers according to claims 1 and 2, said board being characterized in that said third layer (9) of said sound-deadening, soundproofing modular multilayer composite (4) consisting of a low-density layer is realized with fibrous tuft of the TACA ABX type.
A soundproofing, sound-deadening self-supporting modular board (1) for antinoise barriers according to claims 1 and 2, characterized in that said second layer (8) of said sound-deadening, soundproofing multilayer composite (4) in the form of a low-density layer is realized employing mineral woll or an open-cell foamed material.
A soundproofing, sound-deadening self-supporting modular board (1) for antinoise barriers according to claims 1 and 2, said board being characterized in that said second layer (8) of said soundproofing and sound-deadening multilayer composite (4) in the form of a low-density layer has a thickness ranging from 2 to 5 cm.
A soundproofing, sound-deadening self-supporting modular board (1) for antinoise barriers according to claims 1 and 2, said board being characterized in that said second layer (8) of said sound-deadening, soundproofing multilayer composite (4) consisting of a low-density layer has a resistance to air flow ranging from 10,000 to 30,000 Rayls.
A soundproofing, sound-deadening self-supporting modular board (1) for antinoise barriers according to claim 2, said board (1) being characterized in that said fourth (10) layer of said modular multilayer composite (4) is realized with bituminous matter based heavy rolled sheets.
A soundproofing, sound-deadening self-supporting modular board (1) for antinoise barriers according to claims 2 and 13, characterized in that said fourth layer (10) has a weight ranging from 4 to 10 kg/m².
A soundproofing and sound-deadening, self-supporting modular board (1) for antinoise barriers according to claims 2, 13 and 14, said board (1) characterized in that said fourth layer (10) is fastened to the whole set (4) of said first (7) second (8) and third layer (9) by means of a hot-gluing process.