Brick

# Brick

Overview

Discussion

Quotations

I've got knives in my eyes, I'm going home sick.

Throw one at me if you want, hash head. I've got all five senses and I slept last night, that puts me six up on the lot of you.

Which wall's the door in?

You set that poor kid up! You held Dode like a card 'till you could play him.

Maybe I'll just sit here and bleed at you.

[in flashback] You're the only thing I love!

I'm looking to find this big game the Pin's played, not to gum it, but just so when its tail jams in my back I'll know who to bill for the embalming.

Let's take you back upstairs. Back with the living.

Where you were at, with all of us and the Tug a fist away, you've got to use your nut. Allay the situation. So, yeah, you're not scared of me, I got it, but I'm also thinking you're a little nuts now, so you've got that trade off with your standing. But nuts isn't all bad, so maybe it was a good play. I don't know.

Laura Dannon: Fearless flyer.

Encyclopedia

A brick is a block of ceramic
Ceramic
A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...

material used in masonry
Masonry
Masonry is the building of structures from individual units laid in and bound together by mortar; the term masonry can also refer to the units themselves. The common materials of masonry construction are brick, stone, marble, granite, travertine, limestone; concrete block, glass block, stucco, and...

construction, usually laid using various kinds of mortar
Mortar (masonry)
Mortar is a workable paste used to bind construction blocks together and fill the gaps between them. The blocks may be stone, brick, cinder blocks, etc. Mortar becomes hard when it sets, resulting in a rigid aggregate structure. Modern mortars are typically made from a mixture of sand, a binder...

. It has been regarded as one of the longest lasting and strongest building material
Building material
Building material is any material which is used for a construction purpose. Many naturally occurring substances, such as clay, sand, wood and rocks, even twigs and leaves have been used to construct buildings. Apart from naturally occurring materials, many man-made products are in use, some more...

s used throughout history.

## History

The oldest discovered bricks, originally made from shaped mud and dating to before 7500 B.C. were found at Tell Aswad
Tell Aswad , Su-uk-su, Shuksa or Tell Sukas is a large prehistoric, Neolithic Tell, about in size, located around from Damascus in Syria, on a tributary of the Balikh River at the eastern end of the village of Jdeidet el Khass.-Excavation:...

then later in the upper Tigris
Tigris
The Tigris River is the eastern member of the two great rivers that define Mesopotamia, the other being the Euphrates. The river flows south from the mountains of southeastern Turkey through Iraq.-Geography:...

region and in southeast Anatolia
Anatolia
Anatolia is a geographic and historical term denoting the westernmost protrusion of Asia, comprising the majority of the Republic of Turkey...

close to Diyarbakir
Diyarbakir
Diyarbakır is one of the largest cities in southeastern Turkey...

. Other more recent findings, dated between 7,000 and 6,395 B.C., come from Jericho
Jericho
Jericho ; is a city located near the Jordan River in the West Bank of the Palestinian territories. It is the capital of the Jericho Governorate and has a population of more than 20,000. Situated well below sea level on an east-west route north of the Dead Sea, Jericho is the lowest permanently...

and Catal Hüyük. The first sun-dried bricks were made in Mesopotamia (what is now Iraq), in the ancient city of Ur
Ur
Ur was an important city-state in ancient Sumer located at the site of modern Tell el-Muqayyar in Iraq's Dhi Qar Governorate...

in about 4000 BC, although the arch used for drying the bricks was not actually found.

Other examples of civilizations who used mud brick include the ancient Egypt
Ancient Egypt
Ancient Egypt was an ancient civilization of Northeastern Africa, concentrated along the lower reaches of the Nile River in what is now the modern country of Egypt. Egyptian civilization coalesced around 3150 BC with the political unification of Upper and Lower Egypt under the first pharaoh...

ians and the Indus Valley Civilization
Indus Valley Civilization
The Indus Valley Civilization was a Bronze Age civilization that was located in the northwestern region of the Indian subcontinent, consisting of what is now mainly modern-day Pakistan and northwest India...

, where it was used exclusively. In particular, it is evident from the ruins of Buhen
Buhen
Buhen was an ancient Egyptian settlement situated on the West bank of the Nile below the Second Cataract. It is well known for its fortress, probably constructed during the rule of Senusret III, around the year 1860 BC . The site may have been first established as an outpost in Nubia during the...

, Mohenjo-daro
Mohenjo-daro
Mohenjo-daro is an archeological site situated in what is now the province of Sindh, Pakistan. Built around 2600 BC, it was one of the largest settlements of the ancient Indus Valley Civilization, and one of the world's earliest major urban settlements, existing at the same time as the...

and Harappa
Harappa
Harappa is an archaeological site in Punjab, northeast Pakistan, about west of Sahiwal. The site takes its name from a modern village located near the former course of the Ravi River. The current village of Harappa is from the ancient site. Although modern Harappa has a train station left from...

.

The Romans
Ancient Rome
Ancient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....

made use of fired bricks, and the Roman legion
Roman legion
A Roman legion normally indicates the basic ancient Roman army unit recruited specifically from Roman citizens. The organization of legions varied greatly over time but they were typically composed of perhaps 5,000 soldiers, divided into maniples and later into "cohorts"...

s, which operated mobile kiln
Kiln
A kiln is a thermally insulated chamber, or oven, in which a controlled temperature regime is produced. Uses include the hardening, burning or drying of materials...

s , introduced bricks to many parts of the empire. Roman brick
Roman brick
Roman brick can refer either to a type of brick originating in Ancient Rome and spread by the Romans to the lands they conquered; or to a modern type of brick, inspired by the ancient prototypes...

s are often stamped with the mark of the legion that supervised their production. The use of bricks in southern and western Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

, for example, can be traced back to traditions already described by the Roman architect Vitruvius
Vitruvius
Marcus Vitruvius Pollio was a Roman writer, architect and engineer, active in the 1st century BC. He is best known as the author of the multi-volume work De Architectura ....

.

### China

In pre-modern China
History of China
Chinese civilization originated in various regional centers along both the Yellow River and the Yangtze River valleys in the Neolithic era, but the Yellow River is said to be the Cradle of Chinese Civilization. With thousands of years of continuous history, China is one of the world's oldest...

, brick-making was the job of a lowly and unskilled artisan, but a kiln master was respected as a step above the former. Early traces of bricks were found in a ruin site in Xi'an
Xi'an
Xi'an is the capital of the Shaanxi province, and a sub-provincial city in the People's Republic of China. One of the oldest cities in China, with more than 3,100 years of history, the city was known as Chang'an before the Ming Dynasty...

in 2009 dated back about 3800 years ago. Before this discovery, it is widely believed that bricks appeared about 3000 years ago in the Western Zhou
Western Zhou
The Western Zhōu period was the first half of the Zhou Dynasty of ancient China. It began when King Wu of Zhou overthrew the Shang Dynasty at the Battle of Muye. C.H...

dynasty since the earliest bricks were found in Western Zhou
Western Zhou
The Western Zhōu period was the first half of the Zhou Dynasty of ancient China. It began when King Wu of Zhou overthrew the Shang Dynasty at the Battle of Muye. C.H...

ruins. These bricks are the earliest bricks discovered that were made by a fired process. Early descriptions of the production process and glazing
Ceramic glaze
Glaze is a layer or coating of a vitreous substance which has been fired to fuse to a ceramic object to color, decorate, strengthen or waterproof it.-Use:...

techniques used for bricks can be found in the Song Dynasty
Song Dynasty
The Song Dynasty was a ruling dynasty in China between 960 and 1279; it succeeded the Five Dynasties and Ten Kingdoms Period, and was followed by the Yuan Dynasty. It was the first government in world history to issue banknotes or paper money, and the first Chinese government to establish a...

carpenter's manual Yingzao Fashi
Yingzao Fashi
The Yingzao Fashi is a technical treatise on architecture and craftsmanship written by the Chinese author Li Jie , the Directorate of Buildings and Construction during the mid Song Dynasty of China. A promising architect, he revised many older treatises on architecture from 1097 to 1100...

, published in 1103 by the government official Li Jie, who was put in charge of overseeing public works for the central government's construction agency. The historian Timothy Brook
Timothy Brook (historian)
Timothy James Brook , who writes as Timothy Brook and who has had many academic works published, is a distinguished historian specializing in the study of China...

writes of the production process in Ming Dynasty
Ming Dynasty
The Ming Dynasty, also Empire of the Great Ming, was the ruling dynasty of China from 1368 to 1644, following the collapse of the Mongol-led Yuan Dynasty. The Ming, "one of the greatest eras of orderly government and social stability in human history", was the last dynasty in China ruled by ethnic...

China (aided with visual illustrations from the Tiangong Kaiwu
Song Yingxing
Song Yingxing , born in Yichun of Jiangxi, was a Chinese scientist and encyclopedist who lived during the late Ming Dynasty . He was the author of an encyclopedia that covered a wide variety of technical subjects, including the use of gunpowder weapons...

encyclopedic text published in 1637):

...the kilnmaster had to make sure that the temperature inside the kiln stayed at a level that caused the clay to shimmer with the colour of molten gold or silver. He also had to know when to quench the kiln with water so as to produce the surface glaze. To anonymous laborers fell the less skilled stages of brick production: mixing clay and water, driving oxen over the mixture to trample it into a thick paste, scooping the paste into standardized wooden frames (to produce a brick roughly 42 cm long, 20 cm wide, and 10 cm thick), smoothing the surfaces with a wire-strung bow, removing them from the frames, printing the fronts and backs with stamps that indicated where the bricks came from and who made them, loading the kilns with fuel (likelier wood than coal), stacking the bricks in the kiln, removing them to cool while the kilns were still hot, and bundling them into pallets for transportation. It was hot, filthy work.

The idea of signing the worker's name and birth date on the brick and the place where it was made was not new to the Ming era and had little or nothing to do with vanity. As far back as the Qin Dynasty
Qin Dynasty
The Qin Dynasty was the first imperial dynasty of China, lasting from 221 to 207 BC. The Qin state derived its name from its heartland of Qin, in modern-day Shaanxi. The strength of the Qin state was greatly increased by the legalist reforms of Shang Yang in the 4th century BC, during the Warring...

(221 BC–206 BC), the government required blacksmith
Blacksmith
A blacksmith is a person who creates objects from wrought iron or steel by forging the metal; that is, by using tools to hammer, bend, and cut...

s and weapon-makers to engrave their names onto weapons in order to trace the weapons back to them, lest their weapons should prove to be of a lower quality than the standard required by the government.

### Europe

In the 12th century, bricks from Northern-Western Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

were re-introduced to Northern Germany, where an independent tradition evolved. It culminated in the so-called brick Gothic
Brick Gothic
Brick Gothic is a specific style of Gothic architecture common in Northern Europe, especially in Northern Germany and the regions around the Baltic Sea that do not have natural rock resources. The buildings are essentially built from bricks...

, a reduced style of Gothic architecture
Gothic architecture
Gothic architecture is a style of architecture that flourished during the high and late medieval period. It evolved from Romanesque architecture and was succeeded by Renaissance architecture....

that flourished in Northern Europe
Northern Europe
Northern Europe is the northern part or region of Europe. Northern Europe typically refers to the seven countries in the northern part of the European subcontinent which includes Denmark, Estonia, Latvia, Lithuania, Norway, Finland and Sweden...

, especially in the regions around the Baltic Sea
Baltic Sea
The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...

which are without natural rock resources. Brick Gothic buildings, which are built almost exclusively of bricks, are to be found in Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...

, Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

, Poland
Poland
Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...

, and Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

.

During the Renaissance
Renaissance
The Renaissance was a cultural movement that spanned roughly the 14th to the 17th century, beginning in Italy in the Late Middle Ages and later spreading to the rest of Europe. The term is also used more loosely to refer to the historical era, but since the changes of the Renaissance were not...

and the Baroque
Baroque
The Baroque is a period and the style that used exaggerated motion and clear, easily interpreted detail to produce drama, tension, exuberance, and grandeur in sculpture, painting, literature, dance, and music...

, visible brick walls were unpopular and the brickwork
Brickwork
Brickwork is masonry produced by a bricklayer, using bricks and mortar to build up brick structures such as walls. Brickwork is also used to finish corners, door, and window openings, etc...

was often covered with plaster
Plaster
Plaster is a building material used for coating walls and ceilings. Plaster starts as a dry powder similar to mortar or cement and like those materials it is mixed with water to form a paste which liberates heat and then hardens. Unlike mortar and cement, plaster remains quite soft after setting,...

. It was only during the mid-18th century that visible brick walls regained some degree of popularity, as illustrated by the Dutch Quarter of Potsdam
Potsdam
Potsdam is the capital city of the German federal state of Brandenburg and part of the Berlin/Brandenburg Metropolitan Region. It is situated on the River Havel, southwest of Berlin city centre....

, for example.

The transport in bulk of building materials such as bricks over long distances was rare before the age of canals, railways, roads and heavy goods vehicles. Before this time bricks were generally made close to their point of intended use. It has been estimated that in England in the 18th century carrying bricks by horse and cart for ten miles (16 km) over the poor roads then existing could more than double their price.

Bricks were often used for reasons of speed and economy, even in areas where stone was available. The buildings of the Industrial Revolution in Britain were largely constructed of brick and timber due to the demand created. During the building boom of the 19th century in the eastern seaboard cities of Boston
Boston
Boston is the capital of and largest city in Massachusetts, and is one of the oldest cities in the United States. The largest city in New England, Boston is regarded as the unofficial "Capital of New England" for its economic and cultural impact on the entire New England region. The city proper had...

and New York City
New York City
New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...

, for example, locally made bricks were often used in construction in preference to the brownstone
Brownstone
Brownstone is a brown Triassic or Jurassic sandstone which was once a popular building material. The term is also used in the United States to refer to a terraced house clad in this material.-Types:-Apostle Island brownstone:...

s of New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...

and Connecticut
Connecticut
Connecticut is a state in the New England region of the northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, and the state of New York to the west and the south .Connecticut is named for the Connecticut River, the major U.S. river that approximately...

for these reasons.

The trend of building upwards for offices that emerged towards the beginning of the 19th century displaced brick in favor of cast and wrought iron and later steel and concrete
Concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...

. Some early 'skyscrapers' were made in masonry, and demonstrated the limitations of the material – for example, the Monadnock Building
The Monadnock Building , is a skyscraper located at 53 West Jackson Boulevard in the south Loop community area of Chicago, Illinois. The north half of the building was designed by the firm of Burnham & Root and built in 1891...

in Chicago (opened in 1896) is masonry and just 17 stories high; the ground walls are almost 6 feet (1.8 m) thick, clearly building any higher would lead to excessive loss of internal floor space on the lower floors. Brick was revived for high structures in the 1950s following work by the Swiss Federal Institute of Technology
Swiss Federal Institute of Technology
The Swiss Federal Institute of Technology may refer to one of two institutes of higher education in Switzerland:* ETH Zurich in Zurich* École Polytechnique Fédérale de Lausanne in Lausanne...

and the Building Research Establishment
Building Research Establishment
The Building Research Establishment is a former UK government establishment that carries out research, consultancy and testing for the construction and built environment sectors in the United Kingdom...

in Watford
Watford
Watford is a town and borough in Hertfordshire, England, situated northwest of central London and within the bounds of the M25 motorway. The borough is separated from Greater London to the south by the urbanised parish of Watford Rural in the Three Rivers District.Watford was created as an urban...

, UK. This method produced 18-story structures with bearing walls no thicker than a single brick (150–225 mm). This potential has not been fully developed because of the ease and speed in building with other materials; in the late-20th century brick was confined to low- or medium-rise structures or as a thin decorative cladding over concrete-and-steel buildings or for internal non-load-bearing walls.

## Methods of manufacture

"Bricks" for building may be made from clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...

, shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...

, soft slate, calcium silicate
Calcium silicate
Calcium silicate is the chemical compound Ca2SiO4, also known as calcium orthosilicate and sometimes formulated 2CaO.SiO2. It is one of group of compounds obtained by reacting calcium oxide and silica in various ratios e.g. 3CaO.SiO2, Ca3SiO5; 2CaO.SiO2, Ca2SiO4; 3CaO.2SiO2, Ca3Si2O7 and...

, concrete, or shaped from quarried stone. However, true bricks are ceramic, and therefore created by the action of heat and cooling.

Clay is the most common material, with modern clay bricks formed in one of three processes - soft mud, dry press, or extruded.

Normally, brick contains the following ingredients:
1. Silica (sand) - 50% to 60% by weight
2. Alumina (clay) - 20% to 30% by weight
3. Lime - 2 to 5% by weight
4. Iron oxide - 5 to 6% (not greater than 7%) by weight
5. Magnesia - less than 1% by weight

### Mud bricks

The soft mud method is the most common, as it is the most economical. It starts with the raw clay, preferably in a mix with 25-30% sand to reduce shrinkage. The clay is first ground and mixed with water to the desired consistency. The clay is then pressed into steel moulds with a hydraulic
Hydraulics
Hydraulics is a topic in applied science and engineering dealing with the mechanical properties of liquids. Fluid mechanics provides the theoretical foundation for hydraulics, which focuses on the engineering uses of fluid properties. In fluid power, hydraulics is used for the generation, control,...

press. The shaped clay is then fired ("burned") at 900-1000 °C to achieve strength.

#### Rail kilns

In modern brickworks
Brickworks
A brickworks also known as a brick factory, is a factory for the manufacturing of bricks, from clay or shale. Usually a brickworks is located on a clay bedrock often with a quarry for clay on site....

, this is usually done in a continuously fired tunnel kiln
Kiln
A kiln is a thermally insulated chamber, or oven, in which a controlled temperature regime is produced. Uses include the hardening, burning or drying of materials...

, in which the bricks move slowly through the kiln on conveyors, rails, or kiln cars to achieve consistency for all bricks. The bricks often have added lime, ash, and organic matter to speed the burning.

#### Bull's Trench Kilns

In India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, brick making is typically a manual process. The most common type of brick kiln in use there are Bull's Trench Kiln (BTK), based on a design developed by British engineer W. Bull in the late 19th century.

An oval or circular trench, 6–9 meters wide, 2-2.5 meters deep, and 100–150 meters in circumference, is dug. A tall exhaust chimney is constructed in the centre. Half or more of the trench is filled with "green" (unfired) bricks which are stacked in an open lattice pattern to allow airflow. The lattice is capped with a roofing layer of finished brick.

In operation, new green bricks, along with roofing bricks, are stacked at one end of the brick pile; cooled finished bricks are removed from the other end for transport. In the middle the brick workers create a firing zone by dropping fuel (coal, wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...

, oil, debris, and so on.) through access holes in the roof above the trench.

The advantage of the BTK design is a much greater energy efficiency compared with clamp or scove kilns. Sheet metal or boards are used to route the airflow through the brick lattice so that fresh air flows first through the recently burned bricks, heating the air, then through the active burning zone. The air continues through the green brick zone (pre-heating and drying them), and finally out the chimney where the rising gases create suction which pulls air through the system. The reuse of heated air yields savings in fuel cost.

As with the rail process above, the BTK process is continuous. A half dozen laborers working around the clock can fire approximately 15,000-25,000 bricks a day. Unlike the rail process, in the BTK process the bricks do not move. Instead, the locations at which the bricks are loaded, fired, and unloaded gradually rotate through the trench.

### Dry pressed bricks

The dry press method is similar to mud brick but starts with a much thicker clay mix, so it forms more accurate, sharper-edged bricks. The greater force in pressing and the longer burn make this method more expensive.

### Extruded bricks

For extruded bricks the clay is mixed with 10-15% water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

(stiff extrusion) or 20-25% water (soft extrusion). This is forced through a die
Die (manufacturing)
A die is a specialized tool used in manufacturing industries to cut or shape material using a press. Like molds, dies are generally customized to the item they are used to create...

to create a long cable of material of the proper width and depth. This is then cut into bricks of the desired length by a wall of wires. Most structural bricks are made by this method, as it produces hard, dense bricks, and suitable dies can produce holes or other perforations. The introduction of holes reduces the volume of clay needed, and hence the cost. Hollow bricks are lighter and easier to handle, and have thermal properties different from solid bricks. The cut bricks are hardened by drying for 20 to 40 hours at 50 to 150 °C before being fired. The heat for drying is often waste heat from the kiln
Kiln
A kiln is a thermally insulated chamber, or oven, in which a controlled temperature regime is produced. Uses include the hardening, burning or drying of materials...

.
European-style extruded bricks or blocks are used in single-wall construction with finishes applied inside and outside. Their many voids are a greater proportion of the volume than the solid, thin walls of fired clay. Such bricks are made in 15, 25, 30, 42 and 50-cm widths. Some models have very high thermal insulation performance suitable for zero-energy buildings.

### Calcium silicate bricks

The raw materials for calcium silicate
Calcium silicate
Calcium silicate is the chemical compound Ca2SiO4, also known as calcium orthosilicate and sometimes formulated 2CaO.SiO2. It is one of group of compounds obtained by reacting calcium oxide and silica in various ratios e.g. 3CaO.SiO2, Ca3SiO5; 2CaO.SiO2, Ca2SiO4; 3CaO.2SiO2, Ca3Si2O7 and...

bricks include lime
Lime (mineral)
Lime is a general term for calcium-containing inorganic materials, in which carbonates, oxides and hydroxides predominate. Strictly speaking, lime is calcium oxide or calcium hydroxide. It is also the name for a single mineral of the CaO composition, occurring very rarely...

mixed with quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...

, crushed flint
Flint
Flint is a hard, sedimentary cryptocrystalline form of the mineral quartz, categorized as a variety of chert. It occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones. Inside the nodule, flint is usually dark grey, black, green, white, or brown in colour, and...

or crushed siliceous rock together with mineral colourant
Colourant
A colourant or colorant is something added to something else to cause a change in colour. Colourants can be:* Dyes* Pigments* Biological pigments* Inks* Paint* Coloured chemicals...

s. The materials are mixed and left until the lime is completely hydrated, the mixture is then pressed into moulds and cured in an autoclave
Autoclave
An autoclave is an instrument used to sterilize equipment and supplies by subjecting them to high pressure saturated steam at 121 °C for around 15–20 minutes depending on the size of the load and the contents. It was invented by Charles Chamberland in 1879, although a precursor known as the...

for two or three hours to speed the chemical hardening. The finished bricks are very accurate and uniform, although the sharp arris
Arris
Arris is an architectural term that describes the sharp edge formed by the intersection of two surfaces, such as the corner of a masonry unit; the junction between two planes of plaster or any intersection of divergent architectural details...

es need careful handling to avoid damage to brick (and bricklayer). The bricks can be made in a variety of colours, white is common but pastel shades can be achieved.

Csk bricks are common in Sweden, especially in houses built or renovated in the 1970s,, and are known as "Mexitegel" (en: Mexi[can] Bricks).

In India these are known as Fly ash bricks, manufactured using the FaL-G (fly ash, lime and gypsum) process.

Calcium silicate bricks are also manufactured in Canada and the United States, and meet the criteria set forth in ASTM C73 - 10 Standard Specification for Calcium Silicate Brick (Sand-Lime Brick). It has lower embodied energy than cement based man-made stone and clay brick .

## Influence on fired colour

The fired colour of clay bricks is 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 (2,372 °F). Calcium silicate bricks have a wider range of shades and colours, depending on the colourants used. The names of bricks may reflect their origin and colour, such as London stock brick
London stock brick
London stock brick is the type of hand-made brick which was used for the majority of building work in London and South East England until the growth in the use of Flettons and other machine-made bricks in the early 20th century. Its distinctive yellow colour and soft appearance come from the...

and Cambridgeshire White.

"Bricks" formed from concrete
Concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...

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
Salt glaze pottery
Salt glaze pottery is stoneware with a glaze of glossy, translucent and slightly orange-peel-like texture which was formed by throwing common salt into the kiln during the higher temperature part of the firing process. Sodium from the salt reacts with silica in the clay body to form a glassy...

, 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 by some. Only a few stones are suitable for bricks. Common materials are granite
Granite
Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...

, limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....

and sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...

. Other stones may be used (for example, marble
Marble
Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or dolomite.Geologists use the term "marble" to refer to metamorphosed limestone; however stonemasons use the term more broadly to encompass unmetamorphosed limestone.Marble is commonly used for...

, slate
Slate
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. The result is a foliated rock in which the foliation may not correspond to the original sedimentary layering...

, quartzite
Quartzite
Quartzite is a hard metamorphic rock which was originally sandstone. Sandstone is converted into quartzite through heating and pressure usually related to tectonic compression within orogenic belts. Pure quartzite is usually white to gray, though quartzites often occur in various shades of pink...

, and so on.) but these tend to be limited to a particular locality.

## Optimal dimensions, characteristics, and strength

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 101 mm). In most cases, the length of a brick is about twice its width, about eight inches (about 203 mm) or slightly more. This allows bricks to be laid bonded
Brickwork
Brickwork is masonry produced by a bricklayer, using bricks and mortar to build up brick structures such as walls. Brickwork is also used to finish corners, door, and window openings, etc...

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.

A bigger brick makes for a thicker (and thus more insulating) wall. Historically, this meant that bigger bricks were necessary in colder climates (see for instance the slightly larger size of the Russian brick in table below), while a smaller brick was adequate, and more economical, in warmer regions. A notable illustration of this correlation is the Green Gate
Green Gate
The Green Gate in Gdańsk, Poland, is one of the most notable tourist attractions of the city. It is situated between Long Market and the River Motława.-History:...

in Gdansk; built in 1571 of imported Dutch brick, too small for the colder climate of Gdansk, it was notorious for being a chilly and drafty residence. Nowadays this is no longer an issue, as modern walls typically incorporate specialized insulation materials.

The correct brick for a job can be picked from a choice of colour, surface texture, density, weight, absorption and pore structure, thermal characteristics, thermal and moisture movement, and fire resistance.
Face brick ("house brick") sizes, (alphabetical order)
Standard Imperial Metric
9 × 4⅓ × 3 in
Inch
An inch is the name of a unit of length in a number of different systems, including Imperial units, and United States customary units. There are 36 inches in a yard and 12 inches in a foot...

230 × 110 × 76 mm
Millimetre
The millimetre is a unit of length in the metric system, equal to one thousandth of a metre, which is the SI base unit of length....

9 × 4¼ × 2¼ in 228 × 108 × 54 mm
9 × 4¼ × 2¾ in 240 × 115 × 71 mm
9 × 4¼ × 2¾ in 228 × 107 × 69 mm
9 × 4¼ × 2½ in 240 × 115 × 63 mm
10 × 4¾ × 2½ in 250 × 120 × 65 mm
8¾ × 4 × 3 in 222 × 106 × 73 mm
10 × 4¾ × 2½ in 250 × 120 × 62 mm
8½ × 4 × 2½ in 215 × 102.5 × 65 mm
8 × 4 × 2¼ in 203 × 102 × 57 mm

In England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

, the length and the width of the common brick has remained fairly constant over the centuries (but see brick tax
Brick tax
The brick tax was introduced in Great Britain in 1784, during the reign of King George III, to help pay for the wars in the American Colonies. Bricks were initially taxed at 4s per thousand. To mitigate the effect of the tax, manufacturers began to increase the size of their bricks, up to a maximum...

), 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 Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, the usual size of a modern brick is 215 × 102.5 × 65 mm (about × ×  inches), which, with a nominal 10 mm ( inch) mortar joint, forms a unit size of 225 × 112.5 × 75 mm (9 × × 3 inches), for a ratio of 6:3:2.
In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, modern bricks are usually about 8 × 4 ×  inches (203 × 102 × 57 mm).

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. 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 improved 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, and so on.; 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.

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
MPA
-Academic degrees:* Master of Professional Accountancy* Master of Public Administration* Master of Public Affairs* Master of Physician's Assistant-Chemicals:* Medroxyprogesterone acetate, also known by the brand name Depo-Provera* Morpholide of pelargonic acid...

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
MPA
-Academic degrees:* Master of Professional Accountancy* Master of Public Administration* Master of Public Affairs* Master of Physician's Assistant-Chemicals:* Medroxyprogesterone acetate, also known by the brand name Depo-Provera* Morpholide of pelargonic acid...

, although a common house brick is likely to show a range of 20–40 MPa
MPA
-Academic degrees:* Master of Professional Accountancy* Master of Public Administration* Master of Public Affairs* Master of Physician's Assistant-Chemicals:* Medroxyprogesterone acetate, also known by the brand name Depo-Provera* Morpholide of pelargonic acid...

.

## Use

Bricks are used for building and pavement
Pavement (material)
Road surface or pavement is the durable surface material laid down on an area intended to sustain vehicular or foot traffic, such as a road or walkway. In the past cobblestones and granite setts were extensively used, but these surfaces have mostly been replaced by asphalt or concrete. Such...

. 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
Traffic calming
Traffic calming is intended to slow or reduce motor-vehicle traffic in order to improve the living conditions for residents as well as to improve safety for pedestrians and cyclists. Urban planners and traffic engineers have many strategies for traffic calming...

or as a decorative surface in pedestrian precincts. For example, in the early 1900s, most of the streets in the city of Grand Rapids, Michigan
Michigan
Michigan is a U.S. state located in the Great Lakes Region of the United States of America. The name Michigan is the French form of the Ojibwa word mishigamaa, meaning "large water" or "large lake"....

were paved with brick. Today, there are only about 20 blocks of brick paved streets remaining (totalling less than 0.5 percent of all the streets in the city limits).

Bricks in the metallurgy
Metallurgy
Metallurgy is a domain of materials science that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their mixtures, which are called alloys. It is also the technology of metals: the way in which science is applied to their practical use...

and glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...

industries for lining furnace
Furnace
A furnace is a device used for heating. The name derives from Latin fornax, oven.In American English and Canadian English, the term furnace on its own is generally used to describe household heating systems based on a central furnace , and sometimes as a synonym for kiln, a device used in the...

s. They have various uses, especially refractory
Refractory
A refractory material is one that retains its strength at high temperatures. ASTM C71 defines refractories as "non-metallic materials having those chemical and physical properties that make them applicable for structures, or as components of systems, that are exposed to environments above...

bricks such as silica, magnesia
Periclase
Periclase occurs naturally in contact metamorphic rocks and is a major component of most basic refractory bricks. It is a cubic form of magnesium oxide ....

, chamotte
Grog (clay)
Grog, also known as firesand and chamotte, is a ceramic raw material. It has high percentage of silica and alumina. It can be produced by firing selected fire clays to high temperature before grinding and screening to specific particle sizes. It can also be produced from pitchers...

and neutral (chromomagnesite) refractory bricks
Fire brick
A fire brick, firebrick, or refractory brick is a block of refractory ceramic material used in lining furnaces, kilns, fireboxes, and fireplaces. A refractory brick is built primarily to withstand high temperature, but will also usually have a low thermal conductivity for greater energy efficiency...

. This type of brick must have good thermal shock
Thermal shock
Thermal shock is the name given to cracking as a result of rapid temperature change. Glass and ceramic objects are particularly vulnerable to this form of failure, due to their low toughness, low thermal conductivity, and high thermal expansion coefficients...

resistance, refractoriness
Refractory
A refractory material is one that retains its strength at high temperatures. ASTM C71 defines refractories as "non-metallic materials having those chemical and physical properties that make them applicable for structures, or as components of systems, that are exposed to environments above...

under load, high melting point, and satisfactory porosity
Porosity
Porosity or void fraction is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%...

. There is a large refractory brick industry, especially in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, and the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

.

In the United Kingdom, bricks have been used in construction for centuries. Until recently, almost all houses were built almost entirely from bricks. 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.

Engineering brick
Engineering brick
Engineering bricks are a type of brick used where strength, low water porosity or acid resistance are needed.Clay Engineering bricks are defined in British Standard BS 6100 ‘Glossary of building and civil engineering terms’ as ‘brick sized fired clay units having a dense and strong semi vitreous...

s
are used where strength, low water porosity or acid (flu gas) resistance are needed.

In the UK a redbrick university is one founded and built in the Victorian era, often as a technical college
Polytechnic (United Kingdom)
A polytechnic was a type of tertiary education teaching institution in England, Wales, and Northern Ireland. After the passage of the Further and Higher Education Act 1992 they became universities which meant they could award their own degrees. The comparable institutions in Scotland were...

. The term is used as differentiation from older, more classics
Classics
Classics is the branch of the Humanities comprising the languages, literature, philosophy, history, art, archaeology and other culture of the ancient Mediterranean world ; especially Ancient Greece and Ancient Rome during Classical Antiquity Classics (sometimes encompassing Classical Studies or...

-oriented universities.

Colombian architect Rogelio Salmona
Rogelio Salmona
Rogelio Salmona was a Colombian architect of Sephardic and Occitan descent. He was noted for his extensive use of red brick in his buildings and for using natural shapes like spirals, radial geometry and curves in his designs...

was noted for his extensive use of red brick in his buildings and for using natural shapes like spirals, radial geometry and curves in his designs. Most buildings in Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...

are made of brick, given the abundance of clay in equatorial countries like this one.

## Limitations

Starting in the twentieth century, the use of brickwork declined in many areas due to earthquakes. The San Francisco earthquake of 1906
1906 San Francisco earthquake
The San Francisco earthquake of 1906 was a major earthquake that struck San Francisco, California, and the coast of Northern California at 5:12 a.m. on Wednesday, April 18, 1906. The most widely accepted estimate for the magnitude of the earthquake is a moment magnitude of 7.9; however, other...

revealed the weaknesses of brick buildings in earthquake-prone areas. Most buildings in San Francisco collapsed during the earthquake, due to the cement-based mortar used to hold the bricks together. During seismic events, the mortar cracks and crumbles, and the bricks are no longer held together.

• Brick tinting
Brick tinting
Brick tinting is the process of physically tinting bricks to either change the color or blend-in offending areas of brickwork with the surrounding masonry.-References:...

• Brickwork
Brickwork
Brickwork is masonry produced by a bricklayer, using bricks and mortar to build up brick structures such as walls. Brickwork is also used to finish corners, door, and window openings, etc...

• Brickyard
Brickyard
A brickyard is a place or yard where the earthen building material called bricks are made, fired, and stored, or sometimes sold or otherwise distributed from.-See also:...

• Ceramic
Ceramic
A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...

s
Clinker bricks are partially vitrified brick stones used in the construction of buildings.Clinkers are burnt under temperatures so high that the pores of the fuel property are closed by the beginning sinter process. Thus they are considerably denser and therefore heavier than regular bricks...

• Concrete masonry unit (cinder block)
• Fire brick
Fire brick
A fire brick, firebrick, or refractory brick is a block of refractory ceramic material used in lining furnaces, kilns, fireboxes, and fireplaces. A refractory brick is built primarily to withstand high temperature, but will also usually have a low thermal conductivity for greater energy efficiency...

• Masonry
Masonry
Masonry is the building of structures from individual units laid in and bound together by mortar; the term masonry can also refer to the units themselves. The common materials of masonry construction are brick, stone, marble, granite, travertine, limestone; concrete block, glass block, stucco, and...

• Millwall brick
Millwall brick
A Millwall brick is an improvised weapon made of a manipulated newspaper. It was named for supporters of Millwall F.C., who had a stereotyped reputation for football hooliganism. The Millwall brick was allegedly used as a stealth weapon at football matches in England during the 1960s and 1970s...

• Mortar
Mortar (masonry)
Mortar is a workable paste used to bind construction blocks together and fill the gaps between them. The blocks may be stone, brick, cinder blocks, etc. Mortar becomes hard when it sets, resulting in a rigid aggregate structure. Modern mortars are typically made from a mixture of sand, a binder...

• Mudbrick
Mudbrick
A mudbrick is a firefree brick, made of a mixture of clay, mud, sand, and water mixed with a binding material such as rice husks or straw. They use a stiff mixture and let them dry in the sun for 25 days....

• Roman brick
Roman brick
Roman brick can refer either to a type of brick originating in Ancient Rome and spread by the Romans to the lands they conquered; or to a modern type of brick, inspired by the ancient prototypes...

• Tile
Tile
A tile is a manufactured piece of hard-wearing material such as ceramic, stone, metal, or even glass. Tiles are generally used for covering roofs, floors, walls, showers, or other objects such as tabletops...

• Wienerberger
Wienerberger
Wienerberger AG is the world’s largest producer of bricks, and the second-largest European manufacturer of clay roof tiles. It is based in Vienna, Austria...