Mud Day 2011, Westland, Michigan, United States

Mud, in the construction industry, refers to a fluid material used to coat or adhere together items that dries hard such as plaster, stucco, concrete or other similar substances.
Mud that is mostly clay, or a mixture of clay and sand may be used for ceramics, of which one form is the common fired brick, or dried with the inclusion of straw reinforcing to form an unfired adobe brick. Adobe walls are frequently finished with a mud plaster, seen above in the introductory illustration. Such buildings must be protected from groundwater, usually by building upon a masonry, fired brick, rock or rubble foundation, and also from wind-driven rain in damp climates, usually by deep roof overhangs. In extremely dry climates a well drained flat roof may be protected with a well-prepared and properly maintained dried mud coating, viable as the mud will expand when moistened and so become more water resistant.
In ceramics, the making of liquid mud (called slip) is a stage in the process of refinement of the materials, since larger particles will settle from the liquid.
Mud is similar to muck, but lacking significant quantities of humus, and often containing higher proportions of sand.