All about tuff

Tuff in our country is one of the most recognizable types of expensive building stone - in Soviet times, it was actively used by architects, because there were rich deposits of it in the USSR. In modern Russia, tuff is a little more difficult, but now it is much easier to purchase imported goods, because they still build from tuff quite often.

Tuff is described in scientific sources as a natural rock of high porosity. In places of occurrence of the mineral, it often crumbles and, at first glance, is not strong enough, nevertheless it is constantly used, if not as a direct building material, then at least as a facing coating or raw material for the production of concrete.

Despite the large number of voids and apparent fragility, it is almost impossible to find fault with tuff as a building material. Actually, he has only one minus - the stone absorbs water in huge quantities, which, of course, affects the mass of the constructed building and does not always allow you to correctly calculate the margin of safety of the foundation, and when moisture freezes inside the pores and its subsequent expansion, rapid erosion of the structure is possible.

This disadvantage is due precisely to the porosity, but it also provides some advantages, such as the lightness of the material and its high thermal insulation properties. Actually builders have long learned how to protect tuff from penetrating moisture and cold with the help of exterior decoration and insulation.

As for the main physical characteristics of tuff, they are given with a wide range of values, because the mineral is heterogeneous and has completely different properties, depending on which deposit was mined.

Nevertheless, for a general idea of ​​such a material, it is necessary to describe its properties at least in general terms:

• density - 2.4-2.6 t / m3;
• volumetric weight - 0.75-2.05 t / m3;
• hygroscopicity - 23.3% by weight;
• frost resistance - from several tens to several hundred cycles;
• moisture saturation coefficient - 0.57-0.86;
• softening coefficient - 0.72-0.89;
• tensile strength - 13.13-56.4 MPa;
• thermal conductivity - 0.21-0.33 W / degree.

Tuff can be presented in the widest range of colors, which allows you to experiment with the design of buildings without additional coloring or finishing.

However, the enormous popularity of the material is due not only to this, but also to a number of other valuable properties, among which the following are especially worth noting:

• very long service life with a decent level of strength for construction;
• excellent insulation performance (both in terms of heat and sound);
• porosity makes the stone very light, which greatly simplifies transportation over long distances, and with proper protection from moisture, it allows building large-scale structures even on unstable soils;
• immunity to sudden and significant temperature changes.

Weathering and other types of destruction as a result of the impact of atmospheric phenomena were not noticed in the case of him. With a fairly high strength, a loose and porous stone is easily cut, its processing and forming of blocks do not require any special efforts.Finally, in the open air, mined tuff is surprisingly harder and better suited for capital construction.

Tuff is a rather abstract concept, referring to a group of sedimentary rocks, which sometimes do not even look similar. In view of this, when purchasing a material, you should always clarify what kind of raw materials are in question, including the size of the blocks, since the mineral is sold even in the form of a powder for the manufacture of cement based on it.

Let's briefly go over some of the classification criteria for tuffs.

Tuff is a rock, it is formed only where volcanoes previously acted, hot springs beat, geysers functioned. At the same time, the chemical composition of lava or water in the springs could be quite different, and even the method of formation of the mineral was different, so you should not be surprised that completely different types of material are obtained from different deposits.

The tuff that is most recognizable among the inhabitants of the post-Soviet space is best called Armenian - there it is abundantly mined in the Artik region. This material stands out especially well against the background of all the others due to the fact that it has a pink or even slightly purple color, sometimes deviating towards dark brown and black. But one must understand that these are not typical tuff tones, but just unique ones. If you have ever seen a typical Armenian temple, then in the future you will be able to easily identify this stone by eye.

The Caucasus is, in principle, rich in tuff deposits, they are found everywhere here. Georgian tuff is probably the rarest in the world because it has a pleasant golden color. Kabardian tuff, which is already mined on the territory of Russia, is closer to the Armenian one, has pinkish tints, but it is comparatively few and not so beautiful. The spurs of the Caucasian deposits also make it possible to speak of Dagestan and Crimean tuff, and abroad, of the recognizable Iranian yellow tuff.

Despite the common name, tuff is fundamentally different depending on its origin, and even the chemical composition of such a mineral can change. Natural zeolite mineral comes in the following types of origin.

• Volcanic. It is formed in the vicinity of extinct volcanoes, since it is volcanic ash, which, after the eruption, settled and compressed. At least half (and sometimes up to three quarters) of the composition of such a mineral is silicon oxide, another 10-23% is aluminum oxide. Depending on the exact composition, volcanic tuffs are subdivided into even smaller varieties, such as basaltic, andesite, and so on.

• Limestone, or calcareous, also known as travertine. It also has a sedimentary origin, but is somewhat different, since it is formed on the site not of volcanoes, but of geothermal sources. It is a layer formed as a result of precipitation of calcium carbonate (half of the total volume) and oxides of a number of metallic elements.

• Siliceous, or geyserite. It is also associated with the activity of hot springs, but now geysers, which throw a stream of water upward under pressure. The main component differs, which in this case is silicon-based compounds. Unlike its "brothers", it is laid not so much in layers, but in the form of separate stones.

As mentioned above, for the citizens of post-Soviet countries, tuff in general is most associated with its Armenian variety, which is distinguished by pleasant brown, pink and purple hues.

However, given how diverse the chemical composition of this mineral can be, it shouldn't come as a surprise that its color palette is almost unlimited. Roughly speaking, you can choose any color and hope that tuff of this color exists in nature. Another thing is that the nearest required deposit can be quite far away. And this will negatively affect the cost, but in general, even the most rare golden mineral is mined, even if not in Russia, but nearby - in Georgia.

Otherwise, you can count on the acquisition of the most popular shades of stone, which are predictably white and black. In addition, you can stand out by using red varieties of the mineral, although then it already makes sense to pay attention to the Armenian pink "classics".

The use of tuff, in view of the fact that it is durable, lightweight and can be processed without much difficulty, turns out to be very wide. Since ancient times, it has been the most popular building material in the vicinity of the deposits. - slabs are cut from it, and already houses are built from them, which is confirmed by the classical Armenian architecture.

In regions where there is no tuff of their own, and for capital construction it is wiser to use local materials, tuff tiles can serve as a cladding for the facade, and such a finish will certainly add a touch of ancient charm to the structure. Such a facing material is also suitable for the floor.

The most expensive is, of course, one-piece tuff, from which blocks for the construction of walls, the same tiles, and sculptures are cut. It is worth noting that with all the simplicity of linear cutting, the figured processing of tuff blocks is quite expensive, and this is not a pleasure for everyone, but wealthy owners are very fond of tuff sculptures in landscape design.

If tuff is crushed into dust, which is also possible due to its high porosity, it can be sold in bags by analogy with ordinary cement or mixed into various mixtures for preparing concrete or plaster - this way they are more reliable in terms of cracking and last longer.

Although constant contact with water is not very good for a tuff building, the mineral is not forbidden to be used for decorative purposes in aquariums or ponds - there he can freely absorb water, because the aquarium will not become heavier from this.

For more information on tuff, see the video below.