برترین بانک اطلاعاتی سنگ و کارخانجات سنگبری ایران

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Stone and its application

Stone is a natural body made up of a community of one or more minerals. Stone is one of the main materials in construction that is used in most of the work that is done in civil engineering, roads, railways and ports. The most important uses of stone are:

  1. A) Stones that are used as blocks in construction, docks, dams, walls of shelters, etc.
  2. B) Stones used for decorative purposes and building facades. .
  3. C) Stones used for paving, floors and roofs of buildings.

At the beginning of the plan, the intended use should be known and other factors should be determined accordingly. Important factors in choosing the right building stone are: price, color, durability and technical specifications.

The color of the case is more important from the architects’ point of view, although engineers must also consider the color of the stone. Bright colors are usually preferred over dark colors. This is especially important in limestone because most of the dark colors of limestone in the exterior of a building do not last due to sunlight and air pollution. The color of the stone is a feature that is also very important economically. Rare green, azure and red stones are more valuable. Sometimes the distance of vision is important in recognizing the color of the stone. A medium granite granite with pink feldspars will not be seen in the far distance with this feature. Therefore, the monochromatic or multi-colored nature of the stone should be considered at a distance of about 20 to 50 cm from the eye. The color of igneous rocks and silicate changes are related to the color of the constituent feldspars, which depending on the type can take on pink, cream, red, green and white. In sedimentary rocks, the main minerals are usually colorless (such as quartz and calcite). However, the presence of small amounts of impurities causes these stones to become colored. Black and blue due to the presence of organic carbon and green, red and yellow colors can be formed due to the presence of iron oxides and hydroxides as follows: Stability of stone color is one of the important features. And they are practical. Stones made of organic matter (gray and black) will change more. The black color of a gabbro is durable because of the pyroxene minerals, but the black color of limestone, which contains hydrocarbons, is not durable. Pink is a durable granite made of feldspar, but the green color of sandstone is not permanent if it is due to the presence of iron compounds. If black limestone is used in the interior, its color will not change for a long time, but if exposed outside Special weather conditions, especially with high humidity, change color in a short time. The color of some rocks changes or even disappears when exposed to atmospheric conditions. Gray limestones turn white over time, and black limestones tend to be pale gray or yellow-gray. In sandstones and clays, the azure and green color created by iron sulfur is first oxidized to yellowish green and then to yellow or red by oxidation.

Changing the color of the stone damages the goals of the design and its beauty, so you should pay attention to these points when choosing a stone:

  1. A) When choosing the desired stone, pay attention to its function in existing buildings with similar climatic conditions.

Mining and quarrying companies dealing with the stone in question can be good advisors in this regard.

  1. B) Most black limestones outside the building change color due to weather conditions and sunlight.
  2. C) Unstable minerals change color even to a small extent. Before choosing a stone, this can be examined by petrographic study.
  3. D) The polish of the stone will help its color to last.

Durability:

 Durability of a building stone is its stability against chemical and weathering factors. Unfortunately, the durability of the stone, which should be the most important factor in choosing a stone, is often overlooked. There are many expensive structures that have not been chosen in this regard and have suffered from this area. Natural factors that affect this issue include the construction, texture and composition of mineralogy. The location of the stone in the building and its use is another factor that affects the durability of the stone. In addition, the weather conditions are very important. In hot and humid climates, chemical weathering is more effective, and in cold, dry climates, physical weathering is more effective.

Composition:

 Different minerals have different resistance to the onslaught of weathering factors, so it is natural that rocks have different resistance to weathering due to their different constituent minerals, and those that have less resistant minerals are more quickly damaged by different factors. See.

Harmful minerals:

Some specific minerals (iron sulfur) can be considered harmful in all circumstances, while others, such as mica, are only harmful in large quantities and in some rocks, such as sandstone and marble. One of the lesser known causes of discoloration in rocks is the presence of unstable minerals that are easily converted to another mineral. It is the staining of the stone.

Any weakness in the stone structure accelerates the invasive effect of weathering factors. Therefore, seam surfaces, layering surfaces, fault surfaces or any gaps caused by faults or creases (including shear cracks) will all create the right conditions for weathering and frost.

Texture:

 The stone may have coarse-grained or fine-grained grains of the same size, or it may have a porous texture (uneven grains). Coarse-grained rocks break down earlier than fine-grained rocks, are especially sensitive to temperature changes. This type of rupture is related, at least in part, to differences in the coefficients of expansion of rock-forming minerals. Dense rock crumbles later than porous rock. Dense rocks are almost impermeable, so weathering agents cannot act quickly. Open porous and capillary rocks easily absorb water and crack due to frost.

Factors affecting the useful life of building stone

 Many building stones are wasted due to improper extraction. The use of explosives or … may cause cracks in the stone. Some cracks may be microscopic, but even on this scale, they can damage the destroying agent and thus the rock. If care is taken during the extraction, grinding and polishing of the stone, it will cause cracks, seams in the stone, and as a result, the phenomenon of rapid weathering will occur.

– The selected stone should be free of any joints, cracks, crevices or other weaknesses.

– The stone must be tested before selection. The required tests are determined based on the application of the stone.

– Before choosing a stone, it should be examined by microscopic studies and if there are excessive amounts of harmful and unstable minerals, they should be avoided in the building.

   – The density of a stone does not necessarily guarantee its durability.

   – Stones with high water absorption should be used only in dry areas. Highly porous rocks should not be used in cold, humid climates. In special cases, paraffin or special materials can be used to protect the stone.

   – Frost resistance testing is essential for rocks used in cold regions. In general, limestone and sandstone rocks whose cement is limestone are less stable than these environments.

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