Sound Insulation Properties of Vermiculite


Exfoliated vermiculite has a high open porosity, so the filling by it is characterized by a high sound absorption. This property of vermiculite can be used to muffling airborne noise in ceilings of buildings.


Absorbing properties of exfoliated vermiculite depend on thickness of the fill, shape and size of vermiculite grains, the oscillation frequency of the sound.


With an increase in thickness of vermiculite backfill, sound absorption coefficient increases rapidly, reaching a maximum at a thickness of 50 mm. Only  superfine vermiculite's optimal layer thickness can be considered as 40 mm.


In thicker layer of backfill, sound absorbing properties remain the same or even slightly reduce.


Dependence of sound absorption coefficient of exfoliated vermiculite on layer thickness

Type of vermiculite

Sound absorption coefficient at an oscillation frequency of 1,000 Hz and a layer thickness in cm

1 cm

2 cm

3 cm

4 cm

5 cm

6 cm

7 cm

Exfoliated vermiculite

  • Grain Size: 0-10 mm
  • Density: 150 kg/m3









Significant impact on the acoustic properties of backfill provides their grain composition. Optimal grain size is 0.3-0.6 mm vermiculite.


With increasing frequency of the sound vibrations, sound absorption coefficient of vermiculite increases and at a frequency of 1000 Hz reaches 0.7-0.8, which is significantly higher than the standards for acoustic materials (0.4).


It should be noted that ceteris paribus bulk density effect on the sound absorption coefficient is relatively small. Therefore, for acoustic purposes, you can use any vermiculite grain composition.


Dependence of sound absorption coefficient  of expanded vermiculite on the oscillation frequency

Type of vermiculite

Sound absorption coefficient at an oscillation frequency Hz

125 Hz

250 Hz

500 Hz

1000 Hz

2000 Hz

Exfoliated vermiculite

  • Grain Size: 0-10 mm
  • Density: 140 kg/m3
  • Layer thickness: 50 mm







Exfoliated vermiculite has a low modulus of elasticity: static modulus of elasticity is less than 1.5 kg/cm2, the dynamic modulus is about 18 kg/cm2.


This property of exfoliated vermiculite determines its other opportunity and scope of application as an elastic gasket of interfloor overlappings for impact sound insulation. Exfoliated vermiculite, laid as backfill for concrete slab in the construction of the "floating floor" eliminates the indirect transfer of impact sound.


According to the International Classification, sound absorption properties of exfoliated vermiculite with 100 mm layer are referred to Class A, which is assigned only to sound proofers. The sound absorption coefficient of exfoliated vermiculite is above most materials used in construction.


For example, at a frequency of 2000 Hz the sound absorption coefficient of exfoliated vermiculite (layer thickness - 100 mm, grain sizes up to 8 mm) is 1, while for the glass wool - 0.64, for felt - 0.79, and for 23 cm thick brick wall - 0.49.


Exfoliated vermiculite as an soundproofer can be used alone, for example, in insulation of floors, roofs, walls, or as part of concretes, plasters as well as vermiculite boards.


The thickness layer of exfoliated vermiculite influences the acoustic insulation properties: the thicker the layer, the better the sound insulation.


The optimum thickness layer of exfoliated vermiculite in the device of floors and roofs, as well as in filling the gaps between the walls is from 100 to 150 mm. Such amount of vermiculite is sufficient in the premises to show all its unique properties.




This is interesting!

Acoustic properties of exfoliated vermiculite were first noticed and used in shipbuilding.

This lightweight thermal insulation and fireproof material is used for noise reduction as part of the inner plates to the hull. Exfoliated vermiculite provides soundproof for cabins, messrooms, crew space, galleys and control stations on ships and submarines.

20.04.2021   12:01

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