NCMA CCCM key terms

A hollow or solid block molded from cement, aggregates, and water, cured to a specified strength and used as the basic building block in masonry walls and foundations.

The nominal size includes the width of one mortar joint (for example, an 8-inch block measures 7-5/8 inches), while the actual size is the physical measurement of the unit itself.

The standard specification for loadbearing concrete masonry units, setting minimum requirements for compressive strength, absorption, and dimensional tolerances that blocks must meet.

The maximum load a masonry unit, prism, or assembly can carry per unit area before crushing, usually reported in psi or MPa and verified by testing.

A small test assembly of stacked units bonded with mortar, used to measure the combined compressive strength of block, mortar, and grout rather than the unit alone.

A workable mixture of cementitious material, sand, and water that bonds masonry units together, seals joints, and accommodates minor dimensional variations between blocks.

A high-bond-strength mortar commonly specified for structural masonry and below-grade work, offering good tensile bond and moderate compressive strength.

The layer of mortar between masonry units, typically 3/8 inch thick, whose thickness, fullness, and tooling affect the wall's strength and water resistance.

The vertical mortar joint between the ends of adjacent masonry units in a course; it must be filled for structural integrity and to resist water penetration.

The horizontal layer of mortar on which masonry units are laid, distributing load and providing a leveling surface from course to course.

A mortar joint finished with a rounded tool that compacts the mortar and sheds water, producing a slightly recessed profile recommended for exterior masonry.

The process of compacting and shaping mortar joints with a tool while the mortar is thumbprint-hard, improving density, bond, and weather resistance.

A pourable cementitious mixture with high water content used to fill cores and collar joints, bonding reinforcement and units into a monolithic structural element.

A defined height of grout placed in one continuous pour, limited by code (often around 5 feet for low-lift grouting) to prevent segregation and form blowouts.

A temporary opening left at the base of a grouted wall to remove debris and verify grout placement, later sealed with a solid block or mortar.

A pattern in which each unit overlaps half of the unit below, staggering vertical joints to increase wall strength and avoid continuous vertical cracks.

A pattern where units align directly above one another, creating continuous vertical joints; it requires reinforcement or special detailing because of reduced structural capacity.

A formed vertical joint that allows masonry to shrink and move without random cracking; it is not a structural separation and does not accommodate differential movement.

A gap that separates masonry from other building elements or allows for thermal and moisture movement, detailed to keep the wall weathertight while relieving stress.

A general term for any joint designed to absorb dimensional changes in a wall, including control and expansion joints, protecting against cracking and displacement.

A water-resistant material installed at wall bases, sills, and roof intersections to collect moisture and direct it to the exterior through weep holes.

A small opening left in the mortar at the base of a wall or above flashing that lets water drain out of the wall cavity to the exterior face.

A continuous flashing that spans the full wall thickness, collecting water within the wall and directing it outward at the face, often with end dams.

A clear coating applied to masonry surfaces to reduce water absorption and staining while allowing the wall to breathe; it is not a substitute for proper flashing.

A white powdery deposit of water-soluble salts that migrate to the masonry surface and crystallize as moisture evaporates; it is usually removable and cosmetic.

Steel bars placed in grouted cores or bond beams to resist tensile and flexural forces, sized and positioned according to structural design documents.

A horizontal course of masonry with cores filled with grout and reinforcement, used to tie walls together and support loads over openings.

A horizontal member spanning an opening in a wall to support the masonry above it, often a reinforced bond beam in concrete masonry construction.

A vertical projection of masonry from a wall face that stiffens the wall and can carry concentrated loads, often reinforced and grouted.

The arrangement of masonry units in horizontal layers called courses, planned to control unit height, maintain bond, and reach a desired wall height.

A gravity or reinforced retaining structure built from stacked concrete blocks, using unit weight, batter, and sometimes soil reinforcement to hold back earth.

A manufactured concrete unit designed for stacking into retaining walls, often with a lip, pin, or interlock feature that aligns courses and resists sliding.

A high-strength polymeric mesh laid in soil layers behind a retaining wall to reinforce the soil mass and resist pullout forces from the retained earth.

The intentional backward lean of a retaining wall face, typically about 1 inch per foot of height, which improves stability and appearance.

A soil mass strengthened by layers of geogrid or similar inclusions, allowing a retaining wall to be built higher and steeper than an unreinforced gravity wall.

The compacted layer of crushed aggregate beneath pavers or wall units that provides a stable, draining foundation and distributes loads to the subgrade.

The native or engineered soil beneath a pavement or wall system, prepared and compacted to support the layers built above it.

A thin, screeded layer of coarse sand between the base course and pavers that provides a level setting surface and helps interlock the units.

The mechanical densification of soil or aggregate by rolling or vibrating, increasing bearing capacity and reducing settlement under pavements and walls.

Manufactured concrete units with shaped edges and joints that lock together under compaction and joint sand, transferring loads across the pavement surface.

Fine sand swept into the narrow gaps between pavers and compacted, locking units together and limiting water and weed intrusion.

A vibrating machine with a flat plate used to compact base material, bedding sand, and pavers after installation to achieve proper density and interlock.

A rigid border, such as a concrete curb or restrained paver, that holds the pavement edges in place and prevents lateral spreading under load.

A paving system with open-graded materials and gaps that allow stormwater to infiltrate into the base and subgrade, reducing runoff.

Clean, uniformly graded crushed stone placed behind retaining walls and under permeable pavements to collect and carry water away from the structure.

A perforated pipe laid in drainage aggregate at the base of a retaining wall to collect groundwater and discharge it away from the wall.

A geotextile placed between soil and drainage aggregate to prevent fine particles from clogging the stone and drain pipe while allowing water to pass.

An additional load applied at the top of a retaining wall, such as a driveway, slope, or building, which increases lateral earth pressure and must be designed for.

A cutting tool, typically with a diamond blade and water cooling, used to cut concrete pavers and wall units to fit curves, corners, and edges.

A decorative top course or manufactured cap unit that finishes a retaining wall, sheds water, and provides a uniform appearance.