Plaster is one of the materials that is of particular importance in the construction industry, due to its features that have been used in housing since ancient times. Plaster has played an important role in many of the old buildings, especially the Sofia walls, most of which are in Isfahan, and there are many beautiful plaster casts of that era. Gypsum is one of the first steps in the construction of a building that has been demolished around the ground, so needed to paint around the ground, and until the last stages of whitewashing and stone installation are still plastered and even in painting. Buildings also use plaster.
Although in most countries of the world there are underground stone mines, but in Iran, all gypsum mines are surface extracted by open pit mining methods. Gypsum, like most other used stones, is extracted by grinding and blasting. Also, if the deposit is in the form of a hill or a mountain and the plaster layers are along the horizon, it is possible to extract gypsum by continuous extraction machinery. In terms of gypsum production, Iran holds 10% of world production and after the US in Second place.
Plaster preparation resources:
Gypsum comes from cooking and grinding gypsum. Gypsum is a calcium-based building material group that is abundantly found in nature. It is found in almost every part of the earth and is fifth most abundant in nature, in Iran, almost everywhere in the country, especially in the central desert. Gypsum in Formula 2 H2O, Caso4 is a sedimentary rock and The cause of its strong compound affinity is not purely found. Mostly found in combination with carbon or iron oxides. Gypsum is most commonly mixed with lime and clay. Gypsum is either found as hydrous calcium sulfate, also known as gypsum (raw gypsum), or as calcium sulfate without water (Caso4), which is called inderite. To be. Hydrated calcium sulfate is found in various forms. as below:
1 – Marble gypsum which is not used in gypsum and is one of the ornamental stones and because of its softness it is very easy to cut and cut and therefore it is used for making ornaments.
2 – Ordinary gypsum which is non-crystalline and is the most abundant type of gypsum and consumes gypsum and is the subject of this section.
Plaster in the construction industry has many uses, including shaping the color of the building to map around the land and mapping – mortar – plaster – whitening – used in sculpture and casting industries and used in molding. Medical work is needed to break it down. It is also used in the cement and pharmaceutical industries.
Plastering means heating the gypsum gypsum so that we can evaporate 1.5 molecules of water from the crystallization. As mentioned, calcium sulfate gypsum is also crystallized in water molecules. In Formula 2 H2O, Caso4 evaporates 1.5 mol% of gypsum crystallization water at very low heat, as if we give gypsum at about 170 ° C, we lose 1.5 molecules of crystallization water and plummet. The building is converted to Caso4 Formula 2 H2O and lost more of its crystallization water by heating to 300 ° C with a temperature of 1.7 mol / L and converting it to thirsty gypsum to Formula 2 H2O. This plaster has a strong affinity with water so that if it is placed near the open air it absorbs 0.2 molecules of water from the vapor in the air and becomes a crystalline plaster with 0.5 molecules of water.
Building White Plaster:
To produce white building plaster, a mixture of different types of gypsum is first extracted into the production line after two stages of crushing and crushing. This uniform mixture is cooked in a rotating horizontal oven at various temperatures and for a period of time, and calcite is termed calcite gypsum. After leaving the furnace, it is subjected to two stages of Asia and fine crushing. The structural white plaster is screened after grinding and is packaged and provided with homogeneous and specific grading.
Gypsum powder is commonly used in interior building construction.
Micronized gypsum: Micronized gypsum is mainly used in the manufacture of decor. This type of gypsum is made from high quality raw materials.
1. Volume Properties 2. Fire Resistance 3. Acoustic (soundproofing)
4.Exceptional plasticity 5.Colorability property