Bulk or lump basic building materials in accordance with technical standards vary in size. When sorting materials by sieving through a sieve system, the fraction is determined. This means that crushed stone or sand is separated according to the size of the particles or grains.
What fractions is crushed stone?
The most common material in any construction is crushed stone. It is used for the device of travel pads, blind areas, it is a component of the concrete mix. In each case, use a certain size of rubble with its inherent physical characteristics. GOST provides that a fraction is the size of a physical unit of stone that fits into the established framework. There are two main standard fractions (5-25 mm and 25-60 mm) that are used in construction. Modern equipment allows sifting crushed stone in the narrower values that are required when implementing individual tasks - from the smallest (up to 1 centimeter) to very large (from 12 to 30 centimeters).
What is rubble for?
The industrial production of concrete and reinforced concrete structures, as well as asphalt, involves the use of a fine fraction of crushed stone - from 5 to 20 mm. When arranging tram tracks, railway embankments, pillows for roads, larger crushed stone (fractions of 20/65 or 40/70 mm) is more often used.
Large fractions are suitable for the construction of foundations, and in landscaping the largest stone is used - up to 30 cm.
Thus, the fraction is the size of the rubble that has passed the selection, preparation and testing in accordance with the requirements of GOST.
The common indicator for all fractions of the stone is considered to be the cuboid shape of the particles, which is achieved in the process of crushing.
Sand fractions and scope
Sand is used not only in construction, but also in industry, for example, for the manufacture of insulation or glass, for the production of adhesive and dry mixes, putties, self-leveling floors, foundry molds, and for sandblasting. To avoid problems with the choice of raw materials, it is necessary to know its characteristics and purchase exactly the sand that is necessary for a particular type of work.
Sand is classified according to its origin and processing method. It happens river, sea, quarry, quartz, perlite, and for each type there is a regulatory document. For example, GOST standards governing the parameters of raw materials used in cement tests distinguish between multifractional and monofractional quartz sand. Sand from deposits of the Czech Cretaceous Region is considered to be the reference.
A common characteristic for sands of different origin is the size modulus (fraction) - this is when most particles are approximately the same size. So, sand, consisting of grains up to 0.5 cm in diameter, is considered to be very large. Large - 2.5-3.5 mm, medium - 1-2.5 mm, small - from 0.5 to 1.5 millimeters, and smaller grains of sand belong to the category of "thin sand".
River sand is an ideal raw material for the production of concrete products, and quarry sand - for mixing masonry or plaster mortars, foundation works. Quartz sand is mainly used for the production of tiles and polymer products, earthenware and porcelain, for filtering water, welding materials and foundry molds.