Where did he come from?
Natural gypsum is a stone that formed as a result of the evaporation of the ancient ocean 200 million years ago. The origin of gypsum influenced the fact that it is a stone - a breed of sedimentary origin. It is dense, with a fine-grained structure and a sugar-like structure on the fracture, or coarse-grained with randomly arranged crystals. In color, it is yellowish, white and light brown - depending on the various impurities in the rock.
Note! Alabaster is the best material for creating important small details that become part of the home decoration.
The history of gypsum is more than one thousand years old. Its white color, its ability to harden in contact with water, and the possibility of changing its shape made it popular among builders and sculptors. Even in Ancient Egypt it was used for decoration. In Antiquity, he was a favorite material for performing ornaments, sculptures, figurines. Since then, for reasonable and very fair reasons, out of a variety of different materials, it was alabaster that remained the most popular among builders.
Properties, specific gravity and density of gypsum
Alabaster is used for the production of binding materials, interior decoration, in medicine. Also, it is ideal for removing masks, modeling, creating stucco moldings. What is the composition of gypsum? The basis of the composition is a semi-aquatic gypsum. To obtain a construction view of this material, natural gypsum stone is used. Under the action of hot air it is dehydrated and crumbles. When adding water, the alabaster becomes ductile and dries in 6 minutes. The specific gravity of gypsum( density) is 2.32 grams per cubic centimeter.
Interesting! To date, there are 12 different grades of gypsum.
According to the methods of heat treatment, it is divided into two groups: high-baking and low-baking. The last group includes construction, high-strength and molding gypsum, and to the first - estrich and anhydrite cement. The properties of gypsum make it possible to use it without fillers, and cracks do not appear, since it does not shrink, but, on the contrary, increases the volume. If, nevertheless, a necessity arises, sawdust, fire, shavings, slags, expanded clay can serve as an astringent for it.
Advantages and disadvantages of the material
This material has the following useful properties:
- Fast setting. This property is very useful in the production of various forms and installation of beacons for plastering;
- White color is an important feature for decorative decoration;
- Hardness of gypsum is low, which makes it easy;
- Fire resistance and fire safety;
- Good insulation against noise;
- Low conductivity of heat;
- Ecological cleanliness.
In construction it is used mainly for the production of gypsum parts: slabs and panels of partitions, dry plaster, wall stones and so on. It is also necessary for mixing mortar to work with plaster. To reduce the consumption of material, the composition of gypsum is made using sand or other aggregate.
Negative properties include:
- Low water resistance;
- Low strength and instability to mechanical loads;
- Limited shelf life( no more than three months);
- Quick adhesion is poor quality when working with a large amount of plaster.
Note! After three months of storage, alabaster loses up to 50% of its useful properties.
