The present invention relates to a prefabricated sound insulating and sound absorbing panel for building construction, roads, tunnels and the like. The invention further relates to the process for manufacturing such panel.

The need of reducing annoying and/or harmful noises is felt not only in the field of civil and industrial building construction but also in that of roads and road and railway tunnels. Document CN101634176A describes a light panel for building constructions comprising an outer layer and an inner core and wherein blast furnace slag is used as component of the outer layer, whereas the inner core is of polystyrene foam. The outer layer of such known panel exhibits sound insulation features. However, the above known panel has quite limited sound insulation features as it exhibits a structure not suitable for carrying out the dual and necessary function of sound insulating barrier and sound absorbing barrier for the effective noise reduction. Moreover, in the above known panel, while the slag is used as sound insulation means, the same is not structurally distributed in an optimal manner, also considering the shape thereof and the grain size thereof, for carrying out, as said, the dual function of sound insulating barrier and sound absorbing barrier.

Document US-A-2010/0078260 discloses an acoustical barrier material.

Starting from the notion of the above drawbacks, the present invention aims to solve them.

An object of the present invention is to provide a prefabricated panel which concurrently provides a sound insulating barrier and a sound absorbing barrier for the effective reduction of annoying and/or harmful noises in building construction, roads, tunnels and the like.

Another object of the present invention is to provide a prefabricated sound insulating and sound absorbing panel for building construction, roads, tunnels and the like which is easy to manufacture, has a certain effectiveness and is easy to install.

Yet another object of the present invention is to provide a process for manufacturing a prefabricated sound insulating and sound absorbing panel for building construction, roads, tunnels and the like which is quick and easy to manufacture.

In view of such objects, the present invention provides a prefabricated sound insulating and sound absorbing panel for building construction, roads, tunnels and the like the fundamental feature whereof is the object of claim 1.

The essential feature of the process for manufacturing the prefabricated sound insulating and sound absorbing panel for building construction, roads, tunnels and the like, according to the present invention, is the object of claim 7.

Further advantageous features are listed in the dependent claims. All the claims are intended as integrally reported herein.

The present invention will appear more clearly from the following detailed description made with reference to the annexed drawing provided by way of a non-limiting example only, wherein:

• fig. 1 shows a perspective view of an exemplary embodiment of a prefabricated sound insulating and sound absorbing panel for building construction, roads, tunnels and the like, object of the invention;
• fig. 2 shows a perspective enlarged scale view of a tile component of the prefabricated panel according to fig. 1.

General features of the slag in prefabricated construction panels

In general, slag is widely used as inert material for prefabricated construction panels also with sound insulation purposes. In such use, it is mixed with other components in a known manner for forming a layer of the panel (CN101634176A). The known literature does not specifically indicate the shape or grain size of the slag used to this end.

Blast furnace slag (or blast furnace dross) is a by-product of the cast iron manufacturing process during which large amounts of liquid dross are formed having a composition similar to Portland concrete. The dross acquires hydraulic features if, at the exit from the blast furnace, it is suddenly cooled and transformed into porous granules with a vitreous structure (amorphous silica), a material called granular slag. Subsequently, this material is ground so as to obtain a powder having fineness comparable to that of concrete.

It is important to note that, according to the grain size, the slag has both sound insulating (when in powder state) and sound absorbing properties (when in natural granular state).

From a construction viewpoint, basic granulated slag is used for making prefabricated panels, which by itself has hydraulic properties, i.e. the capability of hardening in contact with water. However, since such hardening is per se very slow, in order to accelerate it, basic granulated slag is associated with other binders, which act as hydraulic property activators. Moreover, the slag concrete is particularly suitable for making workpieces that require a high resistance to the disintegrating action of atmospheric agents, as well as in massive casting, due to its feature of having a low hydration heat. Moreover, slag proportionally increases the resistance to chemical attacks: it is particularly indicated for those workpieces that may come into contact with aggressive waters.

It should be noted that slag is treated as non hazardous industrial waste.

Therefore, the use of slag in prefabricated panels improves permeability and resistance to the attack of environmental chemical agents, imparting better duration features to the end product as compared to other blends.

In fig. 1, reference numeral 10 globally indicates an exemplary embodiment of the prefabricated sound insulating and sound absorbing panel for building construction, roads, tunnels and the like, object of the invention.

Said panel 10 comprises a plurality of prefabricated tiles 11 (fig. 2), assembled and steadily fixed to each other, in a geometrical arrangement according to lines and columns, so as to form a prefabricated wall element or the like 12, comprising a back base layer 12.1 substantially shaped as a parallelepiped sheet and a front facing layer 12.2 with a rusticated surface, having a plurality of pyramid cusps 13 with alternating orientation.

Two sturdy U-shaped metal section bars 14, parallel to each another, are respectively steadily fixed on opposite sides of panel 10 and are open outwards: they constitute support and connection elements for making a workpiece with prefabricated modular components.

Each prefabricated tile 11 (fig. 2) comprises, correspondingly and in a single body, two adhering structural layers, i.e.:

• a parallelepiped back base layer 11.1, made with a deep blending of concrete and slag in powder state and forming a barrier with a high sound insulating power, and
• a cusp front facing layer 11.2, made with a deep blending of concrete and slag in natural granulated state, so-called granular slag, and forming a barrier with a high sound absorbing power.

A metal armour 15, for example grid-like, is interposed between said back layer 11.1 and said front facing layer 11.2 of tile 11 for connecting said parts and structurally reinforcing the same tile.

An example of blends for making each of said two layers 11.1, 11.2 of said tile 11 and thus of panel 10 is provided hereinafter.

Foamed clay 5-40%, slag 5-60%, sand 5-40%, concrete 10-30%, added water 5-10%, additive CTC < 2%, gravel 5-50%. The slag is provided as ground powder.

Foamed clay 5-40%, slag 5-60%, sand 5-40%, concrete 10-30%, added water 5-10%, additive CTC < 2%. The slag is provided in natural grain shape, i.e. as so-called granular slag.

Indicative and exemplary dimensions of a prefabricated sound insulating and sound absorbing panel for building construction, roads, tunnels and the like, according to the invention.

The dimensions shall differ according to the different uses and to the features of the positioning place:

• minimum dimensions: length 50 cm , width 25 cm, thickness 15 cm;
• maximum dimensions: length 500 cm, width 150 cm, thickness 50 cm.

As is clear from the above, the panel according to the invention may also be made as a single body (rather than with a plurality of assembled tiles), comprising a back base layer constituting the sound insulating barrier and a front facing layer constituting the sound absorbing barrier.

The process for manufacturing the prefabricated sound insulating and sound absorbing panel for building construction, roads, tunnels and the like, according to the invention, comprises the following steps:

• in a suitably shaped formwork or mould, a first partial casting is made of a deep blending of concrete and slag in natural granulated state (granular slag), so as to form a front facing constituting a barrier with a high sound absorbing power;
• a second partial casting is then made for filling said formwork or mould, of a deep blending of concrete and powder slag, so as to form a back layer constituting a barrier with a high sound insulating power;
• the natural drying and hardening of the workpiece (8 to 12 hours, according to the operating conditions), or the drying and forced hardening in furnace (3 to 5 hours) are then carried out;
• and, finally, the operations for detaching the workpiece from said formwork or mould are carried out.

Advantageously, in said formwork or mould, a suitable metal armour, for example a grid, is positioned on said first casting for reinforcement and connection with said second casting.

As it appears from the above description, the present invention allows the objects described in the introduction of the present description to be achieved in a simple and advantageous manner.