This specification covers lightweight aggregates intended for use in structural concrete in which the prime considerations are reducing the density while maintaining compressive strength of the concrete. Procedures covered in this specification are not intended for job control of concrete. Note—This specification is regarded as adequate to ensure satisfactory lightweight aggregates for most concrete. It is recognized that it may be either more or less restrictive than needed for some conditions and for special purposes, such as fire resistance, fill, and concrete constructions, the use of which is based on load tests rather than conventional design procedures.