1.1 This specification covers special aggregates for use in radiation-shielding concretes in which composition or high specific gravity, or both, are of prime consideration. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 The following precautionary caveat pertains only to the test method portion, Section 8, of this specification:This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.