This method covers determination of the air content and system air metric (SAM) number of freshly mixed concrete from observation of the change in volume of concrete with a sequential change in test pressure. This method is intended for use with concretes and mortars made with aggregates for which the aggregate correction factor can be satisfactorily determined by the technique described in Section 7. It is not applicable to concretes made with light-weight aggregates@ air-cooled blastfurnace slag@ or other aggregates with high porosity. This test method is also not applicable to nonplastic fresh concrete such as is commonly used in the manufacture of pipe and concrete masonry units. The text of this standard references notes and footnotes that provide explanatory information. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements for this standard. The values stated in inch-pound units are to be regarded as the standard. 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. Warning??Fresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin and tissue upon prolonged exposure.