Brick is a small, squared-off building material made of fired clay, mortar, and a range of additives. It is a traditional building material that is used in a variety of applications, ranging from residential buildings to large commercial structures such as stadiums and bridges.
The use of brick has been widespread in many cultures throughout history, and it is still used around the world today. There are thousands of different types of brick, named for their use, size, forming method, origin, quality, texture, and/or materials.
Forming methods include molding, extrusion, and dry-pressing. Molding involves soft, wet clay shaped in a mold and pressed to compact it using a steel plunger set at a certain pressure. The other two methods, dry-pressing and extrusion, start with a much thicker mix of clay, and the brick is compressed with greater force.
Molding typically produces a more irregular shape and sharper outline than extruded brick. A thin layer of sand is usually poured on the surface of the molding clay to provide a smooth, uniform texture and to assist release from the mold.
Some brick is also coated in a range of colorants, coatings, and surface textures. These can include pigments, fluxes or frits (glasses containing colorants), and clays with different amounts of additives to create a range of colors.
Raw clay minerals, including kaolin and shale, make up the main body of brick. These are supplemented with small amounts of barium, manganese, and other additives to produce a range of hues. These additives are also used to increase brick’s resistance to weathering and corrosion, improve fire safety, and prevent efflorescence.
Other ingredients used in the brick-making process may include additives such as ammonium compounds, wetting agents, flocculents and deflocculents to cause particles to cluster and disperse, and chemical additives such as grog (pre-ground, pre-fired material such as scrap brick) to produce brick of a particular color or texture. Some bricks are also coated with glass and metals such as nepheline syenite to create a range of surface textures and to provide corrosion protection.
Brick manufacturing has evolved to the point where most manual brickhandling is eliminated, and a wide range of automated systems can set and dehack bricks at rates of over 18,000 per hour. Some machines can rotate bricks 180 degrees and a number of companies now have robotic brick handlers.
The brick industry employs tens of millions of people worldwide, and it is a major contributor to the economies of South Asia, especially Bangladesh, India, and Nepal. The industry is dominated by migrants from marginalized social groups and a significant percentage of the workers are women.
Construction of brick walls can be a very expensive endeavor, particularly if they are to be built in confined spaces or are curved. As a result, many builders seek alternatives to brick in order to reduce the cost of construction.
For example, masonry units made of concrete are a faster and more economical alternative to brick. However, concrete requires more skill and labor to assemble, and it is less resistant to fire than brick. In addition, concrete is less durable and is more prone to cracking and other structural failures than brick.
