Classification of building stone

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Building stone can be divided according to the following characteristics:

  • According to weight

Building stone can be divided into two classes of light and heavy. If the stone is heavier than 1.8gr/cm3 then it is in heavy class, and if it is lighter, then it is in light class.

  • According to the pressure resistance

In case the pressure resistances of the stones are between 100 to 1000 MPathe stone is considered as high resistance, and if this is between 4 to 200 MPa then the stone is low resistance.

  • Softening coefficient

Softening coefficient of the rock in water is the ratio of the pressure resistance of a rock sample soaked in water to the pressure of the same type of rock in the dry state for at least 24 hours. If this coefficient is between 0.6 to 1, then the rock can be used for construction.

  • Resistant to the acidic liquids

Diabase, granite, diorite, basalt, and quartzite are resistant to acidic liquids.

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  • Resistant to the basic liquids

Dolomite, limestone, magnesite, and marble are resistant to the basic liquids.

  • Resistant to heat

Basalt, tuff, anddiabase are resistant to heat. These stones usually have pressure-resistant higher than 1000 MPa and up to one percent permeability.

  • Foundation and wall rocks

Igneous and sedimentary rocks with softening coefficientof more than 0.7 are commonly used for foundations and the walls located under the ground. The lack of clay minerals, joints, and cracks in these rocks is significant.

  • Stone walls

Igneous, metamorphic, and sedimentary rocks that have pressure-resistant between 4.0 to 50 MPa,the weight of 0.9 to 2.2 gr/cm3, softening coefficient between 0.6 to 0.7, and lack of weathering can be used in stone walls.

  • Facades and floors

Igneous, metamorphic, and sedimentary rocks with the pressure-resistant more than 5 MPa, softening coefficient between 0.7 to 0.9, without joints and cracks, lack of weathering, and clay minerals and soluble minerals can be used in facades and floors.

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  • Road construction

Stones are widely used in bridge construction, under railway tracks, paving, road infrastructure, etc. Various types of igneous, sedimentary, and metamorphic rocks heavier than 2/3 gr/cm3, with pressure resistance higher than 100 MPa, softening coefficient higher than 0.9, less than one percentage of permeability, lack of clay minerals and weathering can be used in road construction.

The resistance of rocks to destruction

Various factors such as pollution of the environment,the decay of metal elements, frost, poor installation operation, and the presence of veins, joints, and cracks destroy the stone.

If the water that is with the soluble salts in the rock evaporates and is repeated during various processes, will increase the volume of crystals in the rock and the surface of the rock will flake. It should be noted that more porous rocks are more susceptible to this damage.

It is worth noting that rocks containing calcium carbonate are more sensitive to acidic environments. Sulfur oxide also combined moisture and oxygen in the air to form sulfur acid, which has destructive effects on limestones and sandstones. It goes without saying that the calcium sulfate formed on the surface of such rocks is usually washed off with water, but on surfaces that are not washed, smoky substances gradually settle on.

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Sometimes frosting destroys the rocks. Rocks with less porosity like marble, granite, and schist suffer less damage, but dolomite, limestone, even sandstone are vulnerable to frost damage.

When it rains, water that falls onto limestone from various metal surfaces, such as copper, creates green spots. Rust from iron and steel alloys is much harder remove than porous rock surfaces and is the most damaged. For this reason, all metal parts used when installing stones must be made of stainless alloys.

Fire rarely caused destruction, but marble, granite, and sandstone would be black stained or even crushed. Fire usually does not damage limestone, and only their bright variety turn to pink due to iron oxidation.

Using stone in construction operations

Using stone in construction operations required to consider the important points. These points will guarantee the improvement of the quality of the building. First of all, you should note that the characteristics of the selected stone should be selected according to the conditions of its use mentioned in the previous article. The nest point is that when using the stone, it should be moistened and then applied.When using stone, the pieces of stone should be placed next to each other so that they are locked in a way and its straps should not be stacked on top of each other. Mortar should also be poured in such a way as to prevent the upper and lower edges of the stone from joining together. Also, the pieces of stone used in the first row should be larger than the top rows. Another important point is that when arranging the stones, they should be based on their natural patterns. This is especially important for layered rocks. Also, during installation, care must be taken that the stones do not move after contact with the mortar. Remember that the installation of stones at ambient temperatures below 5 °C is not appropriate, as this arrangement needs to be protected later from impact and climatic and environmental factors. Great care must also be taken with proper bonding between the stones to make the porcelain stone operation more durable. The last point is that to install plaque stones, you should use stainless steel molds such as bronze to better connect the stone with the mortar.

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Essential properties of stones for use in building

The internal textures of the rock must be undamaged and without weak cracks and veins. Care must be taken that it is non-rotten and uniform. The type of stone chosen should not absorb water and moisture. When choosing a stone, the environmental and atmospheric conditions of the area must be considered. A selected stone should not contain impurities. It should also be noted that the compressive strength for load-bearing stones should not be less than 150 kg/cm2. Abrasion resistance and lack of pores are other notable things.

Standard applications of various types of building stones

Of course, in general, it is not possible to state the law for the use of building stones in well-defined places, because in addition to choosing the type of stone, other elements are also important. For example, thickness, sorting, abrasion, etc. can affect the longevity of a rock in the environment. But considering all these issues, here are some suitable applications for any type of stone.

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Application of travertine

  • Floors
  • Front and back building facades
  • Exterior and interior walls

Application of marmarite

  • Floors
  • Interior walls
  • Indoor stairs

Application of marble

  • Walls of large spaces such as hotels, the entrance of large construction, and corridors of luxurious complexes
  • Wall of the living room in the luxurious house
  • Walls and floors of large religious places

Application of granite

  • Interior walls
  • Floors and parking lot
  • Indoor staircase

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The last word

Iran has a special position in the world in terms of stone type and color diversity. According to official statistics, the definite reserves of construction and decorative stones in Iran are about two million and four hundred thousand tons, of which about 27% is marmarite, 28% is granite, 4% is travertine, 16% is marble, and 10% is porcelain. This issue has made our beloved country Iran, after India, China, and Italy as the fourth-largest producer of stone in the world.

Fortunately, due to the existence of many stone quarries in Iran, stones have a very important and significant role in domestic construction. Different types of stones with different properties and different applications are used to perform various tasks. Proper use of stone in its place is very important, because if improper use of stones, over time we will see their destruction, erosion, crushing, and breaking, which reduces the beauty and strength of the building.

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