American Society for Testing and Materials (ASTM). Current edition approved June l. 2009. Published June 2009. Originally approved in 1931. Last previous edition approved in 2008 as C 90-08. 4 p. This specification covers hollow and solid concrete masonry units made from hydraulic cement, water, and mineral aggregates with or without the inclusion of other materials. There are three classes of concrete masonry units: normal weight, medium weight, and lightweight. These units are suitable for both loadbearing and nonloadbearing applications.