In natural sand and gravel content of gravel grains larger than 5 mm should not be At least 10% and not more than 95% by weight. Enriched with sand and gravel mix depending on the content of gravel grains is divided into five groups: 15 to 25% from 25 to 35% from 35 to 50% from 50 to 65% from 65 to 75% Non-delivery of the enriched sand-gravel-gravel mixture. In this rubble is included in the gravel component of sand and gravel mixture. The largest grain size of gravel (D (Naib)) in natural sand and gravel mix shall be not less than 10 mm and 70 mm. Enriched with sand and gravel must have the highest gravel grain size of one of the following values: 10, 20, 40 or 70 mm.
By agreement of the parties permitted delivery of sand and gravel, with grains of gravel particle size over 70 mm but not exceeding 150 mm. The strength of gravel, which is part of the natural and enriched with sand and gravel, it contains grains of soft rock and frost must meet the requirements of gost 8267-93. Sands that are part of the natural sand and gravel on the grain composition must meet the requirements of gost 8736-93 for large, medium, fine and very fine sand. Sands that make up the rich sand and gravel mix shall meet on the grain composition gost 8736-85 for large, medium and fine sand. The content of particles passing through a sieve with a mesh N 014 in the sands that make up the natural sand and gravel shall not exceed 20% enriched 10% by weight. Contents dust and clay particles in natural sand and gravel mix shall not exceed 5%, including clay lumps 1%, while in the enriched – respectively 3% and 0.5% by weight. Sand-gravel mixtures do not contain inclusions clogging. Natural and enriched with sand and gravel, depending on the size of the total effective specific activity of natural radionuclides Aeff, is used: to produce materials, components and structures, used for construction and renovation of residential and public buildings in Aeff to 370 Bq / kg for materials, components and structures used for the construction of industrial buildings and structures, as well as construction of roads within the territories of settlements and areas of promising development in Aeff than 370 Bq / kg to 740 Bq / kg for construction materials for building roads and airfields outside settlements with more than 740 Aeff Bq / kg to 1500 Bq / kg. If necessary, national regulations in force in the state, the value of the specific effective activity of natural radionuclides may be changed within the limits specified above.