The thickness of mortar layer from which the clay masonry unit
absorbs water is up to 5 mm (Ince et al.
Midwest is one of the principal sources of concrete and clay masonry units
and related supplies in the central United States, with 15 production facilities, distribution yards and showrooms across its home state of Missouri, plus Arkansas, Illinois, Kentucky and Oklahoma.
Zsembery, Manual 2: The Properties of Clay Masonry Units
, Clay Brick and Paver Institution, Baulkham Hills, Sydney, Australia, 2001.
 "Methods of test for masonry units--part 11: determination of water absorption of aggregate concrete, manufactured stone and natural stone masonry units due to capillary action and the initial rate of water absorption of clay masonry units
," UNE-EN 772-11, 2011.
Fired clay masonry units
must comply with the minimum resistance to compression specified in the NTC 4205, when being tested according to standard NTC 4017.