Crushed stone – is a product of rocks breaking obtained by mining of rock in the quarry, which then by "sieving" (way of granite crushing) is processed into crushed stone. Granite is considered to be the most common and widely used rock. Crushed stone can also be obtained during the fragmentation of boulders and gravel.

The main properties of crushed stone from natural stone materials are:
- Activity of natural radionuclides (radioactivity);
- Strength;
- Frost-resistance;
- True, average and bulk density;
- Water absorption and water saturation;
- Grain size and shape.

Additional properties of crushed stone from natural stone materials are:
- Adhesion or adhesiveness (adhesion with bitumen);
- Content of pollutants and chemical contaminants, etc.

Crushed stone is divided by size into fractions. Fraction is the maximum allowable size of a single stone (grain). There are primary and accompanying fractions of crushed stone. The primary fractions are: 5-10mm, 5-20mm, 10-20mm, 20-40mm, 20-65mm, 25-60mm, and 40-70mm. The accompanying fractions are: 0-2mm, 0-5mm, 0-15mm, 0-20mm, 0-40mm, 0-60mm, and 2-5mm. In some cases fractions 70-120mm and 120-150mm are also being used.

Crushed stone from granite in fractions of 5-20mm, at least 5-15mm is in great requisition at the market; it is used in the production of asphalt, concrete and reinforced concrete structures. Crushed granite fractions of 20-40mm, 20-65mm, 25-60mm, 40-70mm are also in steady demand, and are being used in the construction and repair of railway embankments, tram-lines, road beds, construction of buildings during the foundation laying, and are also being used for fragmentation into smaller fractions of crushed stone. The crushed stone is considered to be the main among the natural stone materials used in construction.

Technical requirements for the quality of delivered crushed stone:
The most important characteristic, which is usually considered to be starting point for discussion with the buyer on quality of construction crushed stone - is radioactivity. All products supplied by our company are suitable for all, without exception, construction works as confirmed by the appropriate certificates and sanitary-epidemiological conclusions, special studies carried out by laboratories. This means that all granite crushed stone and other types of high-strength crushed stone supplied by us, are of I class of radioactivity (less than 370Bk/kg).

Grain size of each fraction shall meet the requirements of GOST 8267-93 - Crushed stone and gravel from dense rocks for construction work.

Based on the requirements of  mentioned GOST it is considered that the fraction of crushed stone delivered to the construction site, such as 20-40mm, the number of grains smaller than 20 mm should not exceed 10%, and larger grains - 1,25 * D (50 mm) - not more than 0.5 %. These requirements are necessary for strict observance of the grain size of individual fractions. Compliance with these requirements is reflected by the sieving.

Content of lamellar (bream-shaped - comes from the word "bream", i.e. flat as bream) and prickly grains is to be regulated in crushed stone. Grains of lamellar and prickly form are such grains, the thickness or width of what is less three or more times than the length. Grains of crushed stone are divided into four groups as to shapes (the content of lamellar and prickly shaped grains,% by weight):
- Cuboid - up to 15%
- Improved - from 15% to 25%
- Normal - from 25% to 35%,
- Normal - from 35% to 50%.

It should be noted that the "bream-shaping (flakiness)" - is considered to be one of the most important quality characteristics of crushed stone. Less the flakiness is, the better is quality of crushed stone. Using crushed stone of cuboid form provides the densest compaction.

The presence of lamellar and prickly form grains in crushed stone leads to an increase in intergranular cavity in the mixture. This in turn leads to increased consumption of binder, thus resulting in additional material costs. In addition, cube-shaped grains have a greater strength than the grains of lamellar and prickly form. Consequently, the use of cube-like crushed stone in the production is considered to be more economically feasible.

For those consumers who produce high-quality asphalt, concrete and reinforced concrete (including bridges) structures, the technology of whom requires the use of cube-like crushed stone, we can offer granite, basalt, gabbro-diabase crushed stone of very good quality, with flakiness 8% 12%, and 15% produced in Novgorod, Sverdlovsk, Arkhangelsk, Leningrad regions. For those who need regular crushed stone, we offer supplies from Leningrad, Chelyabinsk, Sverdlovsk, Arkhangelsk regions and Karelia. In this case, the flakiness will not exceed 25%. This type of crushed stone is the most popular within our customers.

The strength of crushed stone is characterized by the initial ultimate compression strength of rock, crushability of crushed stone in compression (crushing) in the cylinder, and wear in the rack drum. These values emulate the resistance of rock material under the effect of vehicles passing the road and mechanical impacts during construction of road structures (laying and compaction by road-rollers).

Depending on the brand, the crushed stone is divided into groups: high-strength - M1200-1400, strength - M800-1200, medium strength - M600-800, weak strength - M300-600, ultra weak strength - M200.

There is a need to regulate the content of grains of weak rocks with ultimate compression strength of the original rock in water-saturated state to 20 MPa. According to GOST 8267-93 crushed stone of M1400, M1200, and M1000 class mast not contain grains of weak rock of more than 5%; crushed stone of M800, M600, and M400 class - more than 10%; crushed stone of M300 and M200 class - more than 15% by weight.

The most demanded is considered to be the granite crushed stone with strength M1200; rarely is being used high-strength granite or basalt crushed stone with strength class M1400-1600. It is mainly used in the production of heavy high-strength concrete structures, bridge bearing structures, foundations.

Dust and clay particles (smaller than 0.05 mm) content in crushed stone is also to be normalized. Moreover, the mixture of fractions is to be isolated from lumps of clay with a particle size from 1.25 mm to a maximum grain size of the crushed stone fraction. For all types and strength classes of crushed stone the content of clay in lumps in the total amount of dust and clay particles should not exceed 0.25% by weight. In the crushed stone from igneous and metamorphic rocks the content of dust and clay particles by weight should not exceed 1%; in the crushed stone of the sedimentary rocks with classes from M600 to M1200 - 2%, while with classes from M200 to M400 - 3%.

Crushed stone frost-resistance is characterized by the number of freezing and thawing cycles. It is permitted to rate the frost-resistance of crushed stone by the number of cycles of saturation in a solution of sodium sulfate with following drying. The crushed stone is divided into frost-resistance classes.

One of the specific characteristics of the crushed stone is adhesion. This parameter reflects the assessment of the quality of adhesion of bituminous binders with the surface of crushed stone. It should be noted that the quality of adhesion affects the color of crushed stone. The best indices of adhesion provides grey and taupe crushed stone.