GB2104568A

GB2104568A - Prefabricated sound-absorbent element

Info

Publication number: GB2104568A
Application number: GB08125536A
Authority: GB
Inventors: Razvan Biznosan; Dan Stoenescu
Original assignee: PREFABRICATE DIN BETON GRANITU
Current assignee: PREFABRICATE DIN BETON GRANITU
Priority date: 1981-08-20
Filing date: 1981-08-20
Publication date: 1983-03-09

Abstract

The element 1 is composed of autoclaved cellular concrete reinforced with a wire net cage. It encloses a mineral wool mat 3 which is exposed by the formation of milled slots in the active face of the element. The central strip of concrete is joined to the back by a column 4. <IMAGE>

Description

SPECIFICATION Prefabricated sound-absorbent element The present invention relates to a prefabricated sound-absorbent element and to the manufacture of such an element on automatic production lines for the manufacture of autoclaved cellular concrete.

The sound-absorbent element can be used in the formation between rooms with special acoustical requirements of sound-absorbing dividing walls having high values of acoustical attenuation coefficient. Also such soundabsorbent elements may be of value in acoustical treatments required for sound reduction in spaces having a high noise level (industrial workshops, meeting halls, waiting rooms, corridors, etc.) for the attenuation of noise in ventilating ducts (damping chambers, noise suppressors), and also for obtaining proper parameters of the acoustical field in rooms for special purposes, such as television and sound studios and rooms for special shows.

It is well known that the acoustical treatments in use present some disadvantages, for example high cost price, the need for specialized manual labour for mounting, and fireproofing difficulties.

Another disadvantage is that the weight of the acoustical treatment loads the building structure.

Moreover in general acoustical treatments use scarce materials (wood, metal, webs of various types of fibre).

In accordance with the present invention there is provided a prefabricated sound-absorbent element comprising a cellular concrete body reinforced with a metallic cage and enclosing a mineral wool board, the body having on one face a pair of longitudinal slits extending through the concrete to the mineral wool board.

Such a sound-absorbent element can be made by a method in which the mineral wool board is mounted on the wire net cage before the concrete is poured and the slits are formed by milling after autoclaving of the concrete.

The invention avoids the disadvantages referred to above because the cost price per unit of the prefabricated sound-absorbent element of the invention is reduced by the use of cheaper materials (mineral-wool and mortar) and the manual labour for assembly of the elements does not need to be highly skilled. The acoustical treatments produced have a high degree of fireresistance and the weight per unit area is smaller than that of present acoustical treatments (having a corresponding strength). The materials used in carrying out acoustical treatments on the basis of the prefabricated sound-absorbing elements of the invention are not scarce.

The invention will be described in more detail with the aid of an example illustrated in the accompanying drawings, in which: Fig. 1 is a front view of a prefabricated soundabsorbent element in accordance with the invention, Fig. 2 is an end view of the element of Fig. 1, Figs. 3 and 4 are sections on the lines A-A and B-B of Fig. 1, respectively, Fig. 5 is a longitudinal section on the line C-C in Fig. 2, Fig. 6 is a plan view of a reinforcing cage for use in the element of Figs. 1 to 5 in a flat condition before bending, and Fig. 7 is a perspective view of the finished element.

The sound-absorbent element shown in the drawings comprises a body 1 of cellular concrete which is reinforced by a cage of wire net 2 shown in Fig. 6. The cage 2 is shown in Fig. 6 in the flat condition but is bent up about the bending lines shown to form five sides of a rectangular box, the sixth side being left open. The body 1 encloses a sheet 3 of mineral wool which is exposed through two parallel slots b in the active face of the element. To ensure the support of the concrete strip between the slots b a column 4 of concrete extends through the mineral wool slab 3 and joins the strip to the back face of the element.

In the manufacture of the element the mineral wool board 3 is prepared by cutting to the required dimensions and a bore is cut out of the centre for the formation of the column 4. The wire net cage 2 is assembled and the board 3 placed within it and the assembly is then mounted on supporting rods in a pouring tank. The concrete mix is poured and the rods removed, after which the crude block is cut to the proper dimensions.

The element is then autoclaved and the shuttering removed after which the slots b are formed by milling through the cellular concrete to expose the mineral wool board.

The resulting sound-absorbent elements have the following advantages: - special acoustic properties with a high sound absorption coefficient of 0.45 to 0.9 over a wide frequency range of 100 to 5000 Hz starting at very low frequencies; special sound insulating properties with Ea-5; - remarkable mechanical properties; - reduced transport costs; - achievement of cheap acoustic treatments, quite light, fire-proof, without a supporting wall, with a special architectural aspect; - low cost, being manufactured of cheap materials (autoclaved cellular concrete, mineral wool) on production lines of high efficiency.

1. A prefabricated sound-absorbent element comprising a cellular concrete body reinforced with a metallic cage and enclosing a mineral wool board, the body having on one face a pair of longitudinal slits extending through the concrete to the mineral wool board.

2. A prefabricated sound-absorbent element substantially as described with reference to the accompanying drawings.

3. A method of making the sound-absorbent element of claim 1 in which the mineral wool

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Prefabricated sound-absorbent element The present invention relates to a prefabricated sound-absorbent element and to the manufacture of such an element on automatic production lines for the manufacture of autoclaved cellular concrete. The sound-absorbent element can be used in the formation between rooms with special acoustical requirements of sound-absorbing dividing walls having high values of acoustical attenuation coefficient. Also such soundabsorbent elements may be of value in acoustical treatments required for sound reduction in spaces having a high noise level (industrial workshops, meeting halls, waiting rooms, corridors, etc.) for the attenuation of noise in ventilating ducts (damping chambers, noise suppressors), and also for obtaining proper parameters of the acoustical field in rooms for special purposes, such as television and sound studios and rooms for special shows. It is well known that the acoustical treatments in use present some disadvantages, for example high cost price, the need for specialized manual labour for mounting, and fireproofing difficulties. Another disadvantage is that the weight of the acoustical treatment loads the building structure. Moreover in general acoustical treatments use scarce materials (wood, metal, webs of various types of fibre). In accordance with the present invention there is provided a prefabricated sound-absorbent element comprising a cellular concrete body reinforced with a metallic cage and enclosing a mineral wool board, the body having on one face a pair of longitudinal slits extending through the concrete to the mineral wool board. Such a sound-absorbent element can be made by a method in which the mineral wool board is mounted on the wire net cage before the concrete is poured and the slits are formed by milling after autoclaving of the concrete. The invention avoids the disadvantages referred to above because the cost price per unit of the prefabricated sound-absorbent element of the invention is reduced by the use of cheaper materials (mineral-wool and mortar) and the manual labour for assembly of the elements does not need to be highly skilled. The acoustical treatments produced have a high degree of fireresistance and the weight per unit area is smaller than that of present acoustical treatments (having a corresponding strength). The materials used in carrying out acoustical treatments on the basis of the prefabricated sound-absorbing elements of the invention are not scarce. The invention will be described in more detail with the aid of an example illustrated in the accompanying drawings, in which: Fig. 1 is a front view of a prefabricated soundabsorbent element in accordance with the invention, Fig. 2 is an end view of the element of Fig. 1, Figs. 3 and 4 are sections on the lines A-A and B-B of Fig. 1, respectively, Fig. 5 is a longitudinal section on the line C-C in Fig. 2, Fig. 6 is a plan view of a reinforcing cage for use in the element of Figs. 1 to 5 in a flat condition before bending, and Fig. 7 is a perspective view of the finished element. The sound-absorbent element shown in the drawings comprises a body 1 of cellular concrete which is reinforced by a cage of wire net 2 shown in Fig. 6. The cage 2 is shown in Fig. 6 in the flat condition but is bent up about the bending lines shown to form five sides of a rectangular box, the sixth side being left open. The body 1 encloses a sheet 3 of mineral wool which is exposed through two parallel slots b in the active face of the element. To ensure the support of the concrete strip between the slots b a column 4 of concrete extends through the mineral wool slab 3 and joins the strip to the back face of the element. In the manufacture of the element the mineral wool board 3 is prepared by cutting to the required dimensions and a bore is cut out of the centre for the formation of the column 4. The wire net cage 2 is assembled and the board 3 placed within it and the assembly is then mounted on supporting rods in a pouring tank. The concrete mix is poured and the rods removed, after which the crude block is cut to the proper dimensions. The element is then autoclaved and the shuttering removed after which the slots b are formed by milling through the cellular concrete to expose the mineral wool board. The resulting sound-absorbent elements have the following advantages: - special acoustic properties with a high sound absorption coefficient of 0.45 to 0.9 over a wide frequency range of 100 to 5000 Hz starting at very low frequencies; special sound insulating properties with Ea-5; - remarkable mechanical properties; - reduced transport costs; - achievement of cheap acoustic treatments, quite light, fire-proof, without a supporting wall, with a special architectural aspect; - low cost, being manufactured of cheap materials (autoclaved cellular concrete, mineral wool) on production lines of high efficiency. CLAIMS

3. A method of making the sound-absorbent element of claim 1 in which the mineral wool board is mounted on the wire net cage before the concrete is poured and the slits are formed by milling after autoclaving of the concrete.

4. A method of making a sound-absorbent element substantially as described with reference to the accompanying drawings.