Classes of the radioactivity of construction materials
Classification of construction materials (as well as natural stone) by total specific activity of natural radionuclides.
Class I, materials with a radioactivity content not exceeding <370 Bq/kg.
Such materials can be used in all types of construction without restrictions (construction of residential and public buildings).
Class II, not exceeding <740 Bq/kg.
Materials belonging to this class can be used for the construction of industrial buildings and for road construction.
Class III, not exceeding <1,350 Bq/kg.
Construction materials belonging to class III can be used within the inhabited localities: for the construction of underground structures or supply lines, covered with a layer of soil not less than 0.5 m thick, the time of staying of people in which does not exceed 50% of the working day; outside the boundaries of the inhabited localities: for road construction; for the construction of dams; for the
construction of other facilities, the staying time of people in which does not exceed 50% of the working day.
Class IV, not exceeding <3,700 Bq/kg.
Based on certain documents of the Ministry of Health of Ukraine, materials of this class can be used for interior and exterior decoration of public facilities (except for children’s institutions), as well as for exterior decoration of the pedestals of residential buildings. More than 200 deposits of natural facing and decorative stone are located in Ukraine. Almost all of them belong to the Class I of natural radiation of construction materials, i.e. can be used for all types of construction without restrictions. However, there are granite deposits in Ukraine belonging to Class II of radioactivity, and therefore the use of this granite is limited in construction (used for exterior facing and finishing, road and industrial construction). Granite is checked for compliance with radiation standards at the stage of extraction in the quarry.
Further examination is made in laboratories at stone processing enterprises, the radioactivity of the material is checked again. The manufacturer of natural stone must have a radiation certificate for the products manufactured. Prior to buying the stone, you can always ask the seller to show you such a certificate.