ASTM C638 − 14 Standard Descriptive Nomenclature of Constituents of Aggregates for Radiation-Shielding Concrete

Scope of ASTM C638 − 14 Standard Descriptive Nomenclature of Constituents of Aggregates for Radiation-Shielding Concrete

1.1 This descriptive nomenclature is intended to give accurate descriptions of some common or important naturally occurring and synthetic constituents of aggregates for radiation-shielding concrete, that, at the same time, are not common or important constituents of concrete aggregates in general use.

While most of the minerals and rocks discussed below may occur in small quantities in aggregates in general use, they are not major constituents of such aggregates.

Common constituents of aggregates in general use are described in Descriptive Nomenclature C294. Radiation shielding concrete often contains such aggregates, but other special aggregates are used in some circumstances.

ASTM C638 − 14 Standard Descriptive Nomenclature of Constituents of Aggregates for Radiation-Shielding Concrete

Types of Materials
4.1 Two classes of materials are described below. The first class consists of minerals and rocks formed from them, and synthetic materials, that have high relative density (specific gravity) and in addition contain substantial proportions of atoms of high or moderately high atomic weight.

They are referred to as heavy or high-density aggregates.

The second class consists of minerals and synthetic glasses of substantial boron content that are particularly effective in absorbing thermal neutrons without producing highly penetrating gamma rays.

The boron-frit glasses are included because of their frequent use.