Prefaced (glazed) concrete unit masonry uses blocks manufactured by bonding a permanent colored facing (typically composed of polyester resins, silica sand and various other chemicals) to a concrete masonry unit, providing a smooth impervious surface. The glazed facings must comply with ASTM C 744, Standard Specification for Prefaced Concrete and Calcium Silicate Masonry Units, which contains minimum requirements for facing quality and dimensional tolerances. In addition, the unit to which the facing is applied must comply with ASTM C 90 when used in loadbearing applications. The glazed surface is waterproof, resistant to staining and graffiti, and highly impact resistant, as well as being resistant to many chemicals and bacteria. Special admixtures and mortars are available for use with glazed units that provide better stain, bacteria, and water penetration resistance. Glazed units are available in a variety of vibrant colors: pastels, earth tones, and even faux granite and marble patterns. They are often used for brightly-colored accent bands, or in gymnasiums, rest rooms, and indoor swimming pools where the stain and moisture resistant finish reduces maintenance. Kitchens and laboratories also benefit from the chemical and bacteria-resistant surface.
04 22 23 Architectural Concrete Unit Masonry
Molded-face concrete unit masonry is a scored concrete masonry unit which is manufactured with one or more vertical scores on the face to simulate additional mortar joints in the wall. Scored units reduce the perceived scale of the masonry while still allowing construction using full sized units.
Fluted concrete unit masonry has ribbed or fluted edges. Units typically have four, six, or eight ribs vertically aligned to form continuous segments in the finished wall. The fluted units can be smooth, split, or striated. Flutes can be produced to provide either a circular or rectangular profile. Fluted concrete masonry units can be specially fabricated to be water repellent, and are produced in an array of colors.
Fluted concrete masonry units are usually laid so that the flutes or ribs align vertically as they are placed. Masons can utilize different bond patterns, such as stack bond or one-third running bond, to align scores in adjacent courses. The bond pattern used will determine the load bearing capacity of the wall.
Exposed aggregate concrete unit masonry, also described as "burnished" or "honed", uses ground face concrete masonry units that are polished after manufacturing to achieve a smooth finish which reveals the natural aggregate colors. The units have the appearance of polished natural stone. The finished look of the ground surface can be altered by changing aggregate type and proportions. Often, specific aggregates will be used to enhance the appearance of the polished surface, while coatings are sometimes used to deepen the color. Ground face units are often scored to achieve a scale other than the conventional 8 x 16 in.
Sandblasted face units are CMU where sand (or abrasive) blasting is used to expose the aggregate in a concrete masonry unit, resulting in a "weathered" look.
Split-faced concrete unit masonry is an architectural concrete masonry unit that costs a bit more than a standard CMU. It is made from a mixture of Portland cement, water, aggregates, and admixtures such as coloring agents, air-entraining materials, accelerators, retarders, or water repellents. Once shaped, compacted, and cured, the solid or hollow concrete units are then split crosswise or lengthwise. This random splitting allows some of the aggregate to break through in various planes, providing a look similar to natural stone.
Architectural concrete unit masonry is used as an architectural finish for interior and exterior walls, partitions, terrace walls, and other enclosures. Decorative CMU with textures, patterns, or other special finishes may be chosen for aesthetic attributes. Some units are available with the same treatment or pattern on both faces, to serve as both exterior and interior finish wall material.