What is preferable - claydite or minvate?
First let's figure out why. You can warm the walls, floors and roof. Now consider the characteristics of the materials between which to make a choice. We are interested primarily in thermal conductivity, in claydite its coefficient is 0.1, but for mineral wool - only 0.04 .Consequently, the latter will release much less heat outside the first, with the same thermal insulation thickness. And now the second important factor is weight. Which is better, weighing up to 250 kilograms per cubic meter of claydite or minvate, the mass of which is not more than 30 kilos for the same cubic meter?
The friability of expanded clay depends on the size of the pellets, which can have a diameter of less than 5 millimeters( sand) and up to 20-40 millimeters, with a large fraction material cheaper.
But conclusions are too early to make. Suppose, for insulation of the ceiling, you have enough 5-cm layer of mineral wool. Accordingly, the claydite will need to pour 12 centimeters. Even if it weighs more fibrous insulation 8 times, it is unlikely that the expanded granules from burned clay will require an increase in the bearing capacity of the walls and foundation. We make a low box for the entire floor area, fill it with expanded clay, close it with vapor barrier, and complete the order. One should also take into account the fact that the smallest particles of mineral wool, getting into the lungs, can lead to serious diseases, and clay - an environmentally friendly product.
How to replace claydite, are there analogs?
If you think that for your purposes, namely - for bulk thermal insulation, clay is heavy, you can refer to other porous and expanded fillings. In particular, an analog of expanded clay, close in properties - agloporite, a pumice with a structure similar to glass. This filler is made of low-melting clays mixed with the burden of coal and shale waste, as well as ash and slags from thermal power plants. However, the environmental friendliness of this material is questionable. Another alternative to expanded clay is expanded perlite, moisture absorption is even lower than that of expanded clay, only 3-5%, but the coefficient of thermal conductivity is only 0.04, as in mineral wool.
The most optimal option than replacing expanded clay - expanded vermiculite. This is an environmentally friendly material, produced from a rock belonging to the group of hydromica( remember the plates of mica, which were inserted into the windows in Russia). For comparison, the coefficient of thermal conductivity of claydite is 0.1, and for vermiculite - 0.08, which is 2 times lower than that of mineral wool. The volumetric weight of a cubic meter of expanded vermiculite is 100 kilograms, which is relatively small. The use of this material will result, in the end, in a thinner layer of backfill, less stress on the floor and will be an acceptable basis for screeding.
What is detrimental to expanded clay, and is it not better to use polystyrene foam?
Often on the Internet there are warnings that along with materials like mineral wool, quite harmful to health, but with remarkable properties as a heater, expanded clay is also a danger. That supposedly after a certain incubation period, the expanded granules begin to release harmful substances. Is it so? First of all, let's turn to the primary source, by which we will mean not the producer, but raw materials. Usual red clay, capable of swelling under the influence of high temperatures. So what is harmful about expanded clay, which is a brick-like material? In the information about supposedly allocated toxins there is no specifics.
Another thing, if you choose, lay as a heater foam or expanded clay. Any insulation requires protection from humidity along with vapor barrier. However, if suddenly it happens that dampness penetrates the thickness of the expanded clay layer, if there is a vented gap, the granules will work as a kind of drainage, and then the moisture will evaporate. Polyfoam has the property of rotting in a damp environment, just a year later it turns black, mold can develop on it. And, most unpleasant, if there is a fire( which would not be desirable), the claydite, like the brick, will not react to it in any way, but the foam will start to produce very corrosive and harmful substances.