SUBCOMMITTEE C09.41 IS RESPONSIBLE FOR ASTM standards dealing with concrete for radiation shielding. This concrete systems subcommittee is assigned the charter of establishing and maintaining the standards needed for regulation of pertinent radiation shielding materials used in concrete. The predecessor subcommittee, designated C09.02.08, was established as a result of a joint symposium conducted by ASTM and the American Nuclear Society in 1965. Results of three years of study by this subcommittee led to the development of ASTM standards as noted: • Specification for Aggregates for Radiation-Shielding Concrete (C 637) • Descriptive Nomenclature of Constituents of Aggregates for Radiation-Shielding Concrete (C 638) [1]