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La correction acoustique

Two methods are used to characterise the absorption properties of a material over the entire audible frequency range:

  • The noise reduction coefficient (NRC) is the average of the sound absorption coefficients measured in the frequency range 250 to 2000 Hertz.
  • The weighted sound absorption coefficient αw also takes into account the perception of the human ear, and is complemented by a shape index which indicates when the product is particularly good at absorbing low (L-index), medium (M-index) or high frequencies (H).

Acoustic attenuation

The airborne sound reduction of a wall is measured in accordance with NF EN ISO 140-3, noting for each frequency the difference in intensity between the sound emitted and the sound measured on the other side of the wall. A curve is then obtained giving the attenuation R as a function of frequency.
From this curve, the single weighted index Rw (C; Ctr) is determined, in dB.

The adaptation terms C and Ctr are used to calculate:

• Reduction of noise from neighbours, industrial activities or airports: RA = Rw + C in dB
• Noise attenuation from land transport infrastructure: RA,tr = Rw + Ctr in dB.
However, it is important to note that according to NF EN ISO 140-3: 1995, “The results of measurements […] should not, therefore, be applied directly in situ, without taking into account other factors that influence sound insulation, including lateral transmission and loss factor.”

Acoustic correction and attenuation of concrete structures: Fibrexpan®

Projiso proposes an innovative solution, based on the spray-on application of Fibrexpan® to improve sound insulation between superimposed spaces. The principle consists in spraying the Fibrexpan® coating in one or more layers to achieve the desired thickness.
Fibrexpan® is a dry, non-toxic, CE-marked material composed of slag wool, hydraulic and semi-synthetic binders and various additives It is supplied in flake format(insérer un lien vers le produit)

Fibrexpan® is a spray-on product; the sprayed thickness will be defined according to the desired acoustic attenuation. Flocking consists in applying Fibrexpan® fibres under pressure using special machines.

The product is carded in a spraying machine that generally comprises a feed hopper, a carding device, a blowing device (fan, turbine or blower), a hose for conveying the mixture to be sprayed to a spray gun using compressed air. Water-fed nozzles are placed around the hose outlet to wet the product before it is sprayed onto the substrate.

The assembly principle consists in fixing an expanded metal sheet to the concrete slab.
Fibrexpan® is then sprayed onto this sheet in one or more layers until the desired thickness is reached.

The thickness of the Fibrexpan® coating to be sprayed onto the concrete slab will vary depending on the desired acoustic attenuation value

Acoustic correction and attenuation of concrete structures

Example: a system consisting of a 200 mm thick slab sprayed with 140 mm of Fibrexpan® according to the application described above will have a sound attenuation of Rw+c = 65 dB compared with 61 dB for a bare slab. These values are taken from calculations based on laboratory tests. On-site results may differ slightly due to the site's configuration and the application conditions

Acoustic correction and attenuation of concrete structures

The coating will be finished with Projiso Sidairless®.
Sidairless® is an aqueous dispersion of vinyl copolymers with inert mineral fillers. Colouring in pastel shades can be done directly on site. Concentrated universal colorants can also be used. It is a fine, ready-to-use coating, specially designed for the surfacing and mechanical reinforcement of fibrous coatings. It is applied using pumps for spray-applied coatings. The product can be churned in a mixing turbine.

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Acoustic correction: Fibrofeu®

Projiso’s Fibrofeu® is a fibrous spray-on mixture used for acoustic correction. Fibrofeu® consists of slag wool, with hydraulic and inorganic binders. It is supplied in the form of light flocons.

Fibrofeu® is applied using a spraying machine. The spraying technique, also known as flocking, consists in applying Fibrofeu® fibres under pressure, using a special spraying machine.
The sprayed thickness will be defined according to the desired acoustic correction rating.

The machine generally comprises a feed hopper, a carding device, a blowing device, a hose for conveying the mixture to be sprayed. A spray gun® and water.

Using Fibrofeu® for acoustic correction

Acoustic correction and attenuation of concrete structures

Take concrete for instance - first, a bonding agent must be applied. Projiso Fixo B® is used for concrete supports. Projiso Fixo B® is a solution of vinyl derivatives with a high molecular weight and a high degree of polymerisation.
Projiso Fixo B® is applied with a brush, roller or low-pressure sprayer on a clean, sound surface.

The coating will be finished with Projiso Fixo Dur® or Sidairless®
Sidairless® is an aqueous dispersion of vinyl copolymers with inert mineral fillers. It is a fine, ready-to-use coating, specially designed for the surfacing and mechanical reinforcement of fibrous coatings. It is applied using pumps for spray-applied coatings.
Colouring in pastel shades can be done directly on site. Concentrated universal colorants can also be used. The product can be churned in a mixing turbine.

 

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LEARN MORE ABOUT FIBROFEU®

Acoustic correction: Fireplaster 270®

Fireplaster 270® is a sprayable powder mixture used for acoustic correction and attenuation of concrete structures. The material is based on plaster, vermiculite and special additives. Fireplaster 270® is sprayed on using a pump/mixer.

This slurry mixture is a mortar that is supplied in powder format. The product is placed in a machine that contains a mixing chamber. Fireplaster 270® is sprayed on using a pump, the size of which depends on the amount of product to be sprayed, with the mixture passing through a hose and a spray gun, after being mixed with air. The product is applied using a spray gun.

The coating finish can be left rough with a surface grain or tinted with Sidairless®.
Sidairless® is a fine, ready-to-use coating. It is an aqueous dispersion of vinyl copolymers with inert mineral fillers. It is applied using pumps for spray-applied coatings.

Want more information?

LEARN MORE ABOUT fireplaster®270

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