ASTM Committee C15 on Manufactured Masonry Units was formed in 1937 and merged with C12 on Manufactured Masonry Units in January 2024 to form C15 on Masonry - Manufactured Masonry Units, Mortars and Grouts. C15 meets twice a year, usually in June and December, with about 50 members attending three days of technical meetings capped by a discussion on relevant topics in the Masonry industry. The Committee, with a membership of 364, currently has jurisdiction of 91 standards, published in the Annual Book of ASTM Standards, Volume 04.05. C15 has 11 subcommittees that maintain jurisdiction over these standards. Information on the subcommittee structure and C15's portfolio of approved standards and work items are available from the List of Subcommittees, Standards and Work Items below. These standards continue to play a preeminent role in all aspects important to the industry of masonry units, including fired clay and shale, concrete, sand-lime and plastic coatings for such units.