uses, dangers, how to use it?

Vermiculite is a natural mineral frequently used in homes for its insulating properties. Vermiculite can present health risks, but if supplied correctly, it is not at all inevitable.

Vermiculite was mainly extracted from the Libby mine in Montana in the United States between 1960 and 1990, known by its trade name: vermiculite. zonolite. Nowadays it is produced in China, South Africa, Australia, Zimbabwe and the United States, but is no longer quite as popular as it was in the 1960s and 1970s.

Areas of application of vermiculite

In the home, both for the construction of new housing and for rehabilitation, vermiculite is generally used as a natural insulatoras is or mixed with concrete, in order to offer better sound and thermal insulation.

The pluses: it’s a eco-material very light, environmentally friendly, inexpensive (approximately 1.5 euros per kilo), non-combustible, unalterable, rot-proof, inert. Vermiculite offers good mechanical resistance and remains stable. In addition, it does not attract insects or rodents.

Vermiculite as thermal and sound insulation

Vermiculite is intended for interior insulation of all types of construction:

• insulation or additional insulation of attic floors,
• insulation or additional insulation of hollow vertical walls, interjoists,
• acoustic correction and upgrading of old floors,
• facade coatings, acoustic correction, anti-condensation, fire protection,
• ceiling tile,
• semi-refractory concrete,
• fire protection plates.

To note : vermiculite is a natural mineral close to the micas family. Before processing, the vermiculite is sorted, calibrated and sieved. This heat treatment (exfoliation) at 900°C results in the exfoliated product which is the one most often marketed and used.

Discover the figures of the global vermiculite production on the Planetoscope

Dangers and precautions related to vermiculite

Another of the advantages of vermiculite is that it does not have any allergenic products.

So, what’s the problem with vermiculite?

The problem is that in nature, vermiculite is often associated with asbestosbut it is not systematic, because it depends on the deposits.

It is therefore necessary to check the risks of possible asbestos contamination. The Libbly mine in Montana, which provided up to 70% of world production until the mid-1980s, contained a natural deposit of amphibolic-type asbestos which contaminated the vermiculite.

How do you know if vermiculite is contaminated or not?

Only a laboratory capable of analyzing vermiculite can make a decision by carrying out tests using three (or more) samples. The aim is to check to what extent the fibers have more or less settled at the bottom of the layer. A sample may very well be negative (less than 0.1%) while the others are contaminated.

Vermiculite and asbestos

Asbestos, a natural mineral fiber which is classified as a carcinogen by the International Agency for Research on Cancer (IARC) and is therefore harmful to health.

It is therefore more the asbestos than the vermiculite itself which poses a problem.

How to protect yourself from vermiculite contaminated with asbestos fibers?

Here are some tips to protect yourself from vermiculite which contains asbestos fibers:

• Do not stir the vermiculite so as not to create clouds of dust.
• Isolate work areas with temporary barriers (plastic sheets
  in polyethylene) in order to avoid the diffusion of dust and fibers.
• Use disposable protective clothing.
• Use respiratory protection equipped with HEPA filters.
• Wet the work area to reduce the spread of fibers.
• Never use compressed air to clean.
• Place waste in appropriate containers.

Vermiculite and gardening

Vermiculite is a rock, composed of a clay structure in layers, whose properties are very appreciated by horticulturists and gardeners.

Vermiculite and plantations

In fact, it offers a large capacity tocation exchange. In other words, it has a good capacity to store and redistribute mineral elementswhich explains why it is widely used in horticulture in the manufacture of certain substrates (soils) among other types of clay (use for seedlings is quite rare).

Cultures sur vermiculite © Onur ERSIN

Vermiculite is very light and is used for lighten the substrateswhich facilitates the growth of quality roots of many plants, for example for roof greening. It can be used for cuttings, sowing and repotting plants. The action of vermiculite is physical and mechanical: it does not provide any nutrients to the seedlings, because it is chemically neutral.

• Vermiculite promotesaeration of crop mixtures and allows gas exchange at the root level.
• Its insulating action protects seeds from temperature variations (to be put into perspective all the same…).
• Used for delicate seedlings, vermiculite is used to regulate humidity and to compensate for any forgetting to water.
• For seeds with long germination, vermiculite prevents successive watering from forming a crust which would hinder the growth of the young plants.
• Vermiculite is sometimes used pure, for certain seedlings such as palm trees, but most often mixed with potting soil or peat, at a rate of 20 to 30%.

Vermiculite and animals

Vermiculite is also used for animal care, in particular it is very useful for incubating the eggs of snakes, lizards and reptiles, amphibians, spiders or crickets.

It is used for the care of living animals when their habitat has high humidity (up to 90%) with a temperature that must remain stable. It serves to capture and retain water, while making it available to plants, but avoiding excessive accumulations.

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