Masonry Magazine June 1997 Page. 22
Glazed brick standards are specified for each particular job. ASTM C-216 (Ref. 2), will be used when a "solid" masonry unit is required. Solid meaning at least 75% of the unit is without coring. ASTM C-652 (Ref. 3), is used when the brick is less than 75% solid and this is what is referred to as a "hollow" masonry unit. With either specified brick standard the minimum compressive strength required is an average of 3000 psi (actually the minimums for glazed brick are more likely to be in the 8,000+ psi range). Most glazed brick are "SW" grade for severe weather conditions. This allows for the brick to be able to absorb a certain amount of moisture and freeze, which causes expansion of the water, then thaw without causing the brick to loose its integrity or fail. Glazed brick generally have tight dimensional tolerances and will be specified according to the desired Type of brick required. Due to these standards very little waste occurs with glazed brick which helps control costs.
Note: There is a new glazed brick standard currently before an ASTM committee that is bringing under one standard, "solid" glazed brick. At this point it contains even more stringent requirements than the two standards currently being used. It should be available sometime in 1998. The "hollow" glazed brick standard will be next. Special decorative glazes, such as, "hot" colors like vibrant reds, oranges and yellows which are double-fired and not covered by any of these standards and to date have no ASTM glaze standard of their own.
Glazed Brick Caveats
Glazed brick are available in many sizes, shapes, and colors. These items vary depending upon each manufacturers' capabilities. The glazed brick sizes range from a standard brick, 2-1/4" x7-5/8", up to an 11-5/8" x 11-5/8" face size. Keep in mind that glazed brick come as stretchers with only one face glazed unless you request other faces to be glazed (no automatic quoins).
Never install a glazed face in a mortar joint (for example never use a quoin as a stretcher in the wall). Proper bonding of the mortar to the glazed face will not take place and can allow water penetration and possible structural problems. If you have leftover brick that you would like to use but with an unwanted glazed side you can etch the glazed side to be bonded by running the saw blade through it a few times. Always keep in mind that the more sides that are glazed the more costly the brick, so be sure the glazed brick you are about to etch is not needed elsewhere on the job.
Availability of the glazed brick is generally 6 to 10 weeks depending on the size and complexity of the order and also the busy conditions of the manufacturing plant. The key is to plan ahead and order early.
Handling
Glazed brick have a hard ceramic finish that is resistant to staining, chipping, and scratches, however, they are very fragile before they are installed and should be handled carefully. When the material arrives at the jobsite it should be stored in a protected area and should not come in direct contact with the ground. Never double-stack the brick cubes. Keep the units dry by covering with a non-staining waterproof cover.
Most manufacturers ship their glazed brick with special cardboard dividers to protect the glazed faces during transit and handling at the jobsite. Keep the glazed brick in this factory packing even when it is placed on the scaffolding. Only when the bricklayer is ready to lay each unit should the packaging be removed. Never use tongs or "pitch" these brick. There should be a normal brick waste allowance of 3-5%.
Wall Construction Recommendations
Water penetration is a primary concern when installing glazed brick. Proper design, detailing and construction are more critical with glazed units than regular face brick. The impervious glazed face does not permit graffiti or moisture to penetrate its surface. It conversely does not allow moisture to get out. Once moisture has penetrated the wall, which it will, through the mortar joints, sills, coping, normal condensation and even capillary contact through the ground, we must provide a way to expel the water. As with any type of masonry construction excessive water buildup can cause problems, especially if subject to freeze-thaw conditions.
To help eliminate water buildup from any brick wall, particularly