Glossary of Concrete Masonry Terms Absorption — The increase in weight of a porous solid body resulting from the penetration of a liquid into its permeable pores usually measured as a percentage of dry weight or in pounds per cubic foot. Admixture — A material other than water, aggregates, and hydraulic cement, used as an ingredient of concrete, mortar, or grout and added to the batch immediately before or during its mixing. Aggregate — Granular material such as natural sand, manufactured sand, expanded clay, shale or slate, pumice, volcanic scoria, bituminous or anthracite cinders, gravel, crushed gravel, crushed stone, heavyweight aggregate such as magnetite or ilmenite, and air-cooled or expanded blast-furnace slag, which when bound together into a conglomerate mass by a matrix forms concrete, mortar, or grout. ASHRAE — American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. ASTM — American Society for Testing and Materials. Bed joint — The horizontal layer of mortar on or in which a masonry unit is laid; may cover entire masonry unit or face shell only. Block, concrete — A hollow or solid unit consisting of portland cement and suitable aggregates combined with water. Other materials such as lime, fly ash, air-entraining agent, or other admixtures may be permitted. Bond — Adhesion and grip of concrete, mortar, or grout to reinforcement or to other surfaces against which it is placed; the arrangement of units in masonry so that vertical joints are discontinuous; the pattern formed by the exposed faces of the units in masonry construction. Brick, concrete — A solid unit having a rectangular prismatic shape usually not larger than 4x4x12 in. made from portland cement and suitable aggregates, with or without the inclusion of other materials. Bullnose block — A unit having one or more rounded exterior corners. Cavity wall — A wall built of two or more wythes of masonry units separated by a continuous air space (with or without insulating materials) and in which the wythes are securely tied together with rigid corrosion resistant metal ties. Cleanout — An opening in the first course of masonry for cleaning mortar droppings prior to grout placement in grouted masonry. Required in high lift grouting. Collar joint — The vertical longitudinal joint between wythes of masonry. Composite wall — A multiple wythe wall in which at least one of the wythes is dissimilar to the other wythe with respect to type or grade of units or mortar. Concrete masonry unit, hollow — A unit whose net crosssectional area in any plane parallel to the bearing surface is less than 75 percent of its gross cross-sectional area measured in the same plane. Concrete masonry unit, solid — A unit whose net crosssectional area in every plane parallel to the bearing surface is 75 percent or more of its gross cross-sectional area measured in the same plane. Control joint — A continuous unbonded masonry joint to regulate the location and amount of separation resulting from the dimensional change of different parts of a structure so as to avoid the development of excessively high stresses. Customized masonry — Architectural masonry units having textured or sculptured surfaces. Methods used to obtain different surface textures include splitting, grinding, forming vertical striations, and causing the units to ‘’slump." Sculpture faces are obtained by forming projecting ribs or flutes, either rounded or angular, as well as vertical and horizontal scoring, recesses, and curved faces. Dampproofing — Prevention of moisture penetration due to capillary action by the addition of one or more coatings of a compound that is impervious to water. Expansion joint — A separation between adjoining parts of a masonry structure which is provided to allow small relative movements such as those caused by thermal changes, to occur without one part affecting an adjacent part. Face shell — The side wall of a hollow concrete masonry unit; generally between 3/4 and 1-1/2-in. thick. Flashing — A thin impervious material placed in mortar joints and through air spaces in masonry to prevent water penetration and/or provide water drainage. Grout — Mixture of cementitious material and aggregate to which sufficient water is added to produce desired placing consisting without segregation of the constituents; the hardened equivalent of such mixtures. Head joint — The vertical mortar joint between ends of masonry units; sometimes called the cross joint. Moisture content — The amount of water contained at the time of sampling expressed as a percentage of the total absorption. Parapet Wall — That part of a wall that extends above the roof level. Parging — The process of applying a coat of cement mortar to the back of the facing material, the face of the backing material, the face of rough masonry, and the earth side of foundation and basement walls (sometimes referred to as pargeting). Pilaster — An integral portion of the wall which projects on one or both sides and acts as a vertical beam, a column, an architectural feature or any combination thereof. Prism — A small masonry test assemblage made with masonry units, mortar, and sometimes grout. Primarily used to predict the strength of full scale masonry members. Shrinkage — Volume change due to loss of moisture or decrease in temperature. Single Wythe Wall — A wall of only one masonry unit in thickness. Slenderness ratio — The ratio of effective length or height of a wall or column to effective thickness; used as a means of assessing the stability of a masonry wall or column. Veneer — A masonry facing which is attached to the backup but not so bonded as to act with it under load. Waterproofing — Prevention of moisture flow through masonry. Web — The cross wall connecting the face shells of a hollow concrete masonry unit. Weep hole — Suitably formed holes or openings placed in the masonry to permit the escape of moisture from the interior of the wall. In retaining walls, a hole through the wall to permit water to flow through the wall to prevent build up of pressure.