Natural stone materials used in construction are subdivided into the following three groups:
- Igneous – those include surface materials and materials, located deeper underground: these can be granite, basalt etc.
- Sediment – secondary rocks, formed under the influence of organisms such as limestone or after destruction (weathering, precipitation) of igneous rocks
- Metamorphic – formed when the structure of the materials from the previous two types is altered under the influence of temperature or pressure. Metamorphic rocks include marble, quartz and gneiss.
Extraction of Natural Rock Materials
Extraction of natural stone materials is carried out either through an open-pit mining, in quarries, or by means of a mining method, suitable for the extraction of materials at a greater depth. Igneous rocks, located deep underground, are mined by blasting while semisolid and soft rock materials are extracted by cutting.
Ways for the Processing of Natural Stone Building Materials:
- Processing through the usage of hammers, or shock treatment
- Processing by milling and grinding or abrasive machining.
Types of Products Obtained after Processing
The products, obtained from the processing of natural stone building materials, include the following types:
- Rock blocks that have volume, exceeding 5 cubic meters
- Cut and sliced stones, with irregular shape of the sides of the pieces, suitable for masonry and for road coverings
- tiling materials
- pavers and curbs, which are derived from igneous rocks, such as granite or syenite
Most Commonly Used Building Materials:
Advantages of granite include hardness and resistance, resistance to low temperatures and water impermeability as well its attractiveness due to its various nuances.
Marble is suitable as a decorative material for cladding and mosaics.
Gneiss is hard and resistant to low temperatures, with a rough surface that prevents sliding; it comes in various shades, suitable for flooring and cladding.
Shell limestone is appealing due to its shelled structure, suitable for facings.
Gneiss – Widely Used for Construction Purposes
It belongs to the metamorphic materials and is formed under the influence of very high temperatures and pressure. This is one of the oldest types of stones in the world, which is widespread everywhere.
Gneissic deposits can be found in the basics of eroded mountains or in glacial formations. Gneiss is the main material found in lands with metamorphic rocks. It rivals granite on its hardness and similarly, it can have different shades. Gneiss is, however, more appealing with its alternating light and dark stripes.
Due to its hardness and attractive appearance, gneiss has various applications in construction. Except for cladding and decoration of interior walls of buildings, it can be used in the creation of decorative nooks, waterfalls and fountains, gravestones and for the decoration of buildings. Its hardness and beautiful surface are the reasons it is used in the creation of kitchen countertops.
Advantages of the Gneiss from Ivaylovgrad
The gneiss from Ivaylovgrad, offered by Valmarg Stone, is famous both in Bulgarian and in other countries. It possesses exceptional hardness and toughness along with a number of other valuable qualities, extremely important in construction:
- Moisture resistance: it has the highest degree of moisture resistance, A1, which is sustained even during repeated changes of humidity of the environment;
- Fire resistance: gneiss possesses the highest degree, A1, which belongs to the non-combustible materials, according to the classification of the EU;
- Cold resistance: even during repeated freezing and thawing;
- Noise and thermal insulation qualities;
- Resistance to chemical solutions, degrading and corrosive agents.