In May 2007, Haoxaing Fei, a retired civil engineer, announced that he had invented a new brick composed of fly ash and water compressed at 4,000 psi (27,939 kPa) for two weeks. Owing to the high concentration of calcium oxide in fly ash, the brick is considered "self-cementing". The brick is toughened using an air entrainment agent, which traps microscopic bubbles inside the brick so that it resists penetration by water, allowing it to withstand up to 100 freeze-thaw cycles. Since the manufacturing method uses a waste by-product rather than clay, and solidification takes place under pressure rather than heat, it has several important environmental benefits. It saves energy, reduces mercury pollution, alleviates the need for landfill disposal of fly ash, and costs 20% less than traditional clay brick manufacture. Liu intends to license his technology to manufacturers in 2008. ^[6][7]

Brick sculpturing on Thornbury Castle, Thornbury, near Bristol, England.
The chimneys were erected in 1514.

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Influence on fired colour

The fired colour of clay bricks is significantly influenced by the chemical and mineral content of raw materials, the firing temperature and the atmosphere in the kiln. For example pink coloured bricks are the result of a high iron content, white or yellow bricks have a higher lime content. Most bricks burn to various red hues, if the temperature is increased the colour moves through dark red, purple and then to brown or grey at around 1300 °C. Calcium silicate bricks have a wider range of shades and colours, depending on the colorants used.

Bricks formed from concrete are usually termed blocks, and are typically pale grey in colour. They are made from a dry, small aggregate concrete which is formed in steel moulds by vibration and compaction in either an "egglayer" or static machine. The finished blocks are cured rather than fired using low-pressure steam. Concrete blocks are manufactured in a much wider range of shapes and sizes than clay bricks and are also available with a wider range of face treatments - a number of which are to simulate the appearance of clay bricks.

An impervious and ornamental surface may be laid on brick either by salt glazing, in which salt is added during the burning process, or by the use of a "slip," which is a glaze material into which the bricks are dipped. Subsequent reheating in the kiln fuses the slip into a glazed surface integral with the brick base.

Natural stone bricks are of limited modern utility, due to their enormous comparative mass, the consequent foundation needs, and the time-consuming and skilled labour needed in their construction and laying. They are very durable and considered more handsome than clay bricks. Only a few stones are suitable for bricks. Common materials are granite, limestone and sandstone. Other stones may be used (e.g. marble, slate, quartzite, etc.) but these tend to be limited to a particular locality.

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Optimal dimensions, characteristics and strength

Loose bricks

For efficient handling and laying bricks must be small enough and light enough to be picked up by the bricklayer using one hand (leaving the other hand free for the trowel). Bricks are usually laid flat and as a result the effective limit on the width of a brick is set by the distance which can conveniently be spanned between the thumb and fingers of one hand, normally about four inches (about 100 mm). In most cases, the length of a brick is about twice its width, about eight inches (about 200 mm) or slightly more. This allows bricks to be laid bonded in a structure to increase its stability and strength (for an example of this, see the illustration of bricks laid in English bond, at the head of this article. The wall is built using alternating courses of stretchers, bricks laid longways and headers, bricks laid crossways. The headers tie the wall together over its width.

The correct brick for a job can be picked from a choice of color, surface texture, density, weight, absorption and pore structure, thermal characteristics, thermal and moisture movement, and fire resistance.

Face brick ("house brick") sizes^[8], from small to large

Standard	Imperial	Metric
United States	8 × 4 × 2¼ inches	203 × 102 × 57 mm
United Kingdom	8½ × 4 × 2½ inches	215 × 102.5 × 65 mm
South Africa	8¾ × 4 × 3 inches	222 × 106 × 73 mm
Australia	9 × 4⅓ × 3 inches	230 × 110 × 76 mm

In England, the length and the width of the common brick has remained fairly constant over the centuries, but the depth has varied from about two inches (about 51 mm) or smaller in earlier times to about two and a half inches (about 64 mm) more recently. In the United States, modern bricks are usually about 8 × 4 × 2.25 inches (203 × 102 × 57 mm). In the United Kingdom, the usual ("work") size of a modern brick is 215 × 102.5 × 65 mm (about 8.5 × 4 × 2.5 inches), which, with a nominal 10 mm mortar joint, forms a "coordinating" or fitted size of 225 × 112.5 × 75 mm, for a ratio of 6:3:2.

Some brickmakers create innovative sizes and shapes for bricks used for plastering (and therefore not visible) where their inherent mechanical properties are more important than the visual ones.^[9] These bricks are usually slightly larger, but not as large as blocks and offer the following advantages:

• A slightly larger brick requires less mortar and handling (fewer bricks) which reduces cost
• Ribbed exterior aids plastering
• More complex interior cavities allow improves insulation, while maintaining strength.

Blocks have a much greater range of sizes. Standard coordinating sizes in length and height (in mm) include 400×200, 450×150, 450×200, 450×225, 450×300, 600×150, 600×200, and 600×225; depths (work size, mm) include 60, 75, 90, 100, 115, 140, 150, 190, 200, 225, and 250. They are usable across this range as they are lighter than clay bricks. The density of solid clay bricks is around 2,000 kg/m³: this is reduced by frogging, hollow bricks, etc.; but aerated autoclaved concrete, even as a solid brick, can have densities in the range of 450–850 kg/m³.

Bricks may also be classified as solid (less than 25% perforations by volume, although the brick may be "frogged," having indentations on one of the longer faces), perforated (containing a pattern of small holes through the brick removing no more than 25% of the volume), cellular (containing a pattern of holes removing more than 20% of the volume, but closed on one face), or hollow (containing a pattern of large holes removing more than 25% of the brick's volume). Blocks may be solid, cellular or hollow

The term "frog" for the indentation on one bed of the brick is a word that often excites curiosity as to its origin. The most likely explanation is that brickmakers also call the block that is placed in the mould to form the indentation a frog. Modern brickmakers usually use plastic frogs but in the past they were made of wood. When these are wet and have clay on them they resemble the amphibious kind of frog and this is where they got their name. Over time this term also came to refer to the indentation left by them.[Matthews 2006]

The compressive strength of bricks produced in the United States ranges from about 1000 lbf/in² to 15,000 lbf/in² (7 to 105 MPa or N/mm² ), varying according to the use to which the brick are to be put. In England clay bricks can have strengths of up to 100 MPa, although a common house brick is likely to show a range of 20–40 MPa.

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Use

A brick section of the old Dixie Highway East Florida Connector on the west side of Lake Lily in Maitland, Florida. It was built in 1915 or 1916, paved over at some point, and restored in 1999.

In the early 1900s, most of the streets in the city of Grand Rapids, Michigan were paved with brick. Today, there are only about 20 blocks of brick paved streets remaining (totaling less than 0.5 percent of all the streets in the city limits).^[10]

Bricks are used for building and pavement. In the USA, brick pavement was found incapable of withstanding heavy traffic, but it is coming back into use as a method of traffic calming or as a decorative surface in pedestrian precincts.

Bricks are also used in the metallurgy and glass industries for lining furnaces. They have various uses, especially refractory bricks such as silica, magnesia, chamotte and neutral (chromomagnesite) refractory bricks. This type of brick must have good thermal shock resistance, refractoriness under load, high melting point, and satisfactory porosity. There is a large refractory brick industry, especially in the United Kingdom, Japan and the U.S.A..

In the United Kingdom, bricks have been used in construction for centuries. Until recently, many houses were built almost entirely from red bricks. This use is particularly common in areas of northern England and some outskirts of London, where rows of terraced houses were rapidly and cheaply built to house local workers^{[citation needed]}. These houses have survived to the present day. Although many houses in the UK are now built using a mixture of concrete blocks and other materials, many houses are skinned with a layer of bricks on the outside for aesthetic appeal.

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See also

Wikimedia Commons has media related to:

Bricks

Look up Brick in
Wiktionary, the free dictionary.

• Adobe
• Brick tinting
• Brickwork
• Ceramics
• Fire brick
• Masonry
• Mortar
• Millwall brick
• Mudbrick
• Roman brick
• Wienerberger

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Gallery

A brick kiln,Tamilnadu, India	Brickwork, United States.	Brick sculpturing on Thornbury Castle, Thornbury, near Bristol, England. The chimneys were erected in 1514	Frauenkirche (Munich), erected 1468-1488, looking up at the towers
Mudéjar brick church tower in Teruel (14th c.)	Brick cart, Mumbai, India	Porotherm style clay block brick	Ishtar Gate of Babylon

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Notes

This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (February 2008)

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References

• Brook, Timothy. (1998). The Confusions of Pleasure: Commerce and Culture in Ming China. Berkeley: University of California Press. ISBN 0-520-22154-0
• Campbell, James W. P., and Will Pryce. 2003. Brick : a world history. London ; New York: Thames & Hudson.
• M.Kornmann and CTTB, Clay bricks and roof tiles, manufacturing and properties, Lasim (Paris) 2007 ISBN 2-9517765-6-X

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External links

• Use of old solid Red Clay Bricks as alternative for refractory firebricks.
• Brick in 20th century architecture
• The Hudson River Brick Industry
• European Tile and Brick Producers Association