Brick has been in use for thousands of years from the earliest civilizations to the most current buildings. Simply put, it lasts! Brick is made from clay or shale and fired in a kiln at approximately 2000 degrees Fahrenheit to fuse the particles together. It continues to be used throughout the world because it looks great in both traditional or contemporary architecture, is readily available in all colors, textures and sizes, won’t burn, and requires minimal maintenance.
Brick can be used for its structural capacity or can be the facade of a building. Its design possibilities are limited only by your imagination.
Extruded brick are created using clay and/or shale in a stiff mud process. This differs from the soft mud process used with molded brick. The stiff mud process uses clay and/or shale with a lower water content than the soft mud process. The mix is extruded through a die and is cut into smaller units and ultimately into the size of the desired brick taking into account any shrinkage during the drying and firing process.
Most extruded brick have core holes and crisp edges as opposed to molded brick.
Sand Molded brick are brick that have been produced typically in a wooden mold. Clay and/or shale in a soft-mud process is forced either by hand or machine into a wood mold. The wood mold contains a dusting of sand to help release the newly formed brick from the mold. Sometimes iron oxide is added to the dusting of sand which helps to create different colors in the brick blend in the firing process.
Waterstruck brick are very similar to sand molded brick in that they are typically produced in a wooden mold as well using a soft mud process. However, the wood mold does not use sand but is instead wet before the clay is placed in the mold to help release the newly formed waterstruck brick. No iron oxides are used to enhance the color. The color is determined totally by the firing process.
All molded brick are typically 100% solid and have irregular edges due to the molding process which adds to the character of the project.
Brick is thought of as red however brick is available in all colors from white to black and everything in between. Many clays and shales burn red and flashing the kiln changes the brick range to a combination of red and black. Some clays when fired burn as a buff color while certain additives to the clay mix make the brick a brown color. Almost all colors are available.
Brick come in all sizes as shown below
Type of Brick – W x H x L
modular brick – 3&5/8” x 2&1/4” x 7&5/8”
norman brick – 3&5/8” x 2&1/4” x 11&5/8”
econo brick – 3&5/8” x 3&5/8” x 7&5/8”
utility brick – 3&5/8” x 3&5/8” x 11&5/8”
stylo brick – 3&5/8” x 7&5/8” x 7&5/8”
roman brick – 3&5/8” x 1&5/8” x 11&5/8”
There are many other sizes available as well.
Textures include a sand finish found on a sand molded brick of course but also found on a sand finished extruded brick. Waterstruck brick have their own special finish from the folds of the wet clay coming out of the wood mold along with the irregularity of molded brick to begin with.
Extruded brick can have a smooth finish, a wirecut finish, a bark type finish, and many other types of finishes that are the result of using different rollers.
Mortar joints are a significant part of a brick wall. The color of the mortar along with the style of tooling the joints can make quite a change in the overall appearance of the wall. Jointing styles include concave joints, weathered joints, v joints, grapevine joints, beaded joints and even raked joints. While some joints are better at resisting water penetration, they all add different aesthetics to the finished wall.
Face Brick Properties are governed by ASTM specifications typically ASTM c216 Standard Specification for Facing Brick (Solid Masonry Units made from Clay or Shale). The terminology can be somewhat misleading as the title mentions “Solid Masonry Units” however the specification allows cored units but they must be at least 75% solid as determined by the gross cross-sectional area. Most extruded facebrick are cored and are thereby covered by this specification as long as they meet the 75% requirement.
Facebrick are classified in two grades; Grade SW or Severe Weathering or Grade MW or Moderate Weathering. These grades have certain physical requirements including compressive strength, maximum water absorption by the 5 hour boiling method and a maximum saturation coefficient which is determined as a ratio of the 24 hour cold water absorption to the 5 hour boiling absorption. The saturation coefficient may not apply depending upon the results of a 24 hour cold water absorption test on a representative sample of 5 brick.
ASTM c216 includes a map of the United States showing a weathering index for all regions and has grade recommendations depending upon the weathering index of the region where and how the brick will be used.
Three types of Brick are covered by ASTM c216. They are FBS, FBX and FBA. Each have different tolerances. FBS is the basic standard brick tolerance. FBX has a more precise tolerance while FBA brick create architectural effects from its irregularities. Each of these types have different requirements for tolerances on dimensions, chippage, and distortion.
The International Masonry Institute (IMI) is a strategic alliance between the International Union of Bricklayers and Allied Craftworkers and the contractors who employ those members. Through education, technical support, research and training the IMI works to provide a more efficient construction delivery system.