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Brick
The oldest discovered bricks, originally made from shaped mud and dating before 7500 BC, were found at Tell Aswad, in the upper Tigris region and in southeast Anatolia close to Diyarbakir. These early units were not fired in a kiln but were simply dried in the sun, creating a material that would become the foundation of human settlement. At the site of Çatalhöyük, mudbrick construction was used from approximately 7,400 BC, marking a pivotal shift from temporary shelters to permanent communities. In the Jordan Valley, mudbrick structures dating to 7,200 BC utilized the first bricks with dimensions of 30 by 15 by 7.5 centimeters, establishing a standard size that would echo through millennia. The South Asian inhabitants of Mehrgarh constructed air-dried mudbrick structures between 7000 and 3300 BC, later evolving into the ancient Indus Valley cities of Mohenjo-daro and Harappa. By 3000 BC, ceramic or fired brick was used in early Indus Valley cities like Kalibangan, signaling a technological leap that would allow for more durable and complex architecture. The Great Bath at Mohenjo-daro and the granary of Harappa stand as testaments to the rise of monumental baked brick architecture in the middle of the third millennium BC, where a uniformity to the brick sizes throughout the Indus Valley region conformed to a 1:2:4 thickness, width, and length ratio. As the Indus civilization began its decline at the start of the second millennium BC, Harappans migrated east, spreading their knowledge of brickmaking technology to cities like Pataliputra, Kausambi, and Ujjain, where there was an enormous demand for kiln-made bricks.
Kilns And The Roman Legion
By 604 BC, bricks were the construction materials for architectural wonders such as the Hanging Gardens of Babylon, where glazed fired bricks were put into practice, showcasing the potential of fired clay to create lasting beauty. In Neolithic China, the earliest fired bricks appeared around 4400 BC at Chengtoushan, a walled settlement of the Daxi culture. These bricks were made of red clay, fired on all sides to above 600 degrees Celsius, and used as flooring for houses. By the Qujialing period in 3300 BC, fired bricks were being used to pave roads and as building foundations at Chengtoushan. The use of fired bricks in Chinese city walls first appeared in the Eastern Han dynasty between 25 AD and 220 AD, and the oldest extant brick building above ground is possibly the Songyue Pagoda, dated to 523 AD. The floors of the three pits of the Terracotta Army were paved with an estimated 230,000 bricks, with the majority measuring 28 by 14 by 7 centimeters, following a 4:2:1 ratio. The use of fired bricks in China was first mass-produced during the construction of the tomb of China's first Emperor, Qin Shi Huangdi. In the Mediterranean, early civilizations including the Ancient Greeks and Romans adopted the use of fired bricks. By the early first century CE, standardized fired bricks were being heavily produced in Rome. The Roman legions operated mobile kilns, and built large brick structures throughout the Roman Empire, stamping the bricks with the seal of the legion. Notable mentions of Roman brick structures are the Herculaneum gate of Pompeii and the baths of Caracalla. The Roman Basilica Aula Palatina in Trier, Germany, built with fired bricks in the fourth century, served as an audience hall for Constantine I, demonstrating the structural capabilities of the material.
Where were the oldest discovered bricks found and when were they made?
The oldest discovered bricks were found at Tell Aswad in the upper Tigris region and southeast Anatolia close to Diyarbakir, dating before 7500 BC. These early units were made from shaped mud and dried in the sun rather than fired in a kiln.
When did the Indus Valley civilization begin using fired bricks and what was the standard ratio?
Ceramic or fired brick was used in early Indus Valley cities like Kalibangan by 3000 BC. The brick sizes throughout the Indus Valley region conformed to a 1:2:4 thickness, width, and length ratio.
Who patented the first brick-making machine and when was it patented?
Richard A. Ver Valen of Haverstraw, New York, patented the first brick-making machine in 1852. Henry Clayton later patented a machine in 1855 that could produce up to 25,000 bricks daily with minimal supervision.
What determines the color of fired clay bricks and what temperature creates grey bricks?
The color of fired clay bricks is influenced by the chemical and mineral content of the raw materials, the firing temperature, and the atmosphere in the kiln. As the temperature increases to around 1000 degrees Celsius, the color moves to brown or grey.
What is the standard size of a modern brick in the United Kingdom from 1965?
The usual size of a modern brick from 1965 in the United Kingdom is 215 by 102.5 by 65 millimeters. With a nominal 10 millimeter mortar joint, this forms a unit size of 225 by 112.5 by 75 millimeters for a ratio of 6:3:2.
Why did the use of brickwork decline in some areas during the 20th century?
The use of brickwork declined in some areas due to concerns about earthquakes following events like the San Francisco earthquake of 1906 and the 1933 Long Beach earthquake. Unreinforced brick masonry was found to be weak during seismic events because the mortar cracks and crumbles.
Production of bricks increased massively with the onset of the Industrial Revolution and the rise in factory building in England. For reasons of speed and economy, bricks were increasingly preferred as building material to stone, even in areas where the stone was readily available. It was at this time in London that bright red brick was chosen for construction to make the buildings more visible in the heavy fog and to help prevent traffic accidents. The transition from the traditional method of production known as hand-moulding to a mechanised form of mass-production slowly took place during the first half of the nineteenth century. The first brick-making machine was patented by Richard A. Ver Valen of Haverstraw, New York, in 1852. The Bradley & Craven Ltd 'Stiff-Plastic Brickmaking Machine' was patented in 1853, and Bradley & Craven went on to be a dominant manufacturer of brickmaking machinery. Henry Clayton, employed at the Atlas Works in Middlesex, England, in 1855, patented a brick-making machine that was capable of producing up to 25,000 bricks daily with minimal supervision. His mechanical apparatus soon achieved widespread attention after it was adopted for use by the South Eastern Railway Company for brick-making at their factory near Folkestone. At the end of the 19th century, the Hudson River region of New York State would become the world's largest brick manufacturing region, with 130 brickyards lining the shores of the Hudson River from Mechanicsville to Haverstraw and employing 8,000 people. At its peak, about 1 billion bricks were produced a year, with many being sent to New York City for use in its construction industry. The demand for high office building construction at the turn of the 20th century led to a much greater use of cast and wrought iron, and later, steel and concrete. The use of brick for skyscraper construction severely limited the size of the building, as the Monadnock Building, built in 1896 in Chicago, required exceptionally thick walls to maintain the structural integrity of its 17 storeys.
The Chemistry Of Color And Clay
The colour of fired clay bricks is influenced by the chemical and mineral content of the raw materials, the firing temperature, and the atmosphere in the kiln. For example, pink bricks are the result of a high iron content, while white or yellow bricks have a higher lime content. Most bricks burn to various red hues; as the temperature is increased the colour moves through dark red, purple, and then to brown or grey at around 1000 degrees Celsius. The names of bricks may reflect their origin and colour, such as London stock brick and Cambridgeshire White. Brick tinting may be performed to change the colour of bricks to blend-in areas of brickwork with the surrounding masonry. 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. Calcium-silicate bricks are also called sandlime or flintlime bricks, depending on their ingredients. Rather than being made with clay they are made with lime binding the silicate material. The raw materials for calcium-silicate bricks include lime mixed in a proportion of about 1 to 10 with sand, quartz, crushed flint, or crushed siliceous rock together with mineral colourants. The materials are mixed and left until the lime is completely hydrated; the mixture is then pressed into moulds and cured in an autoclave for three to fourteen hours to speed the chemical hardening. The finished bricks are very accurate and uniform, although the sharp arrises need careful handling to avoid damage to brick and bricklayer. The bricks can be made in a variety of colours; white, black, buff, and grey-blues are common, and pastel shades can be achieved. This type of brick is common in Sweden as well as Russia and other post-Soviet countries, especially in houses built or renovated in the 1970s.
The Geometry Of The Wall
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 10 centimeters. In most cases, the length of a brick is twice its width plus the width of a mortar joint, about 20 centimeters or slightly more. This allows bricks to be laid bonded in a structure which increases stability and strength. 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. In fact, this wall is built in a variation of English bond called English cross bond where the successive layers of stretchers are displaced horizontally from each other by half a brick length. In true English bond, the perpendicular lines of the stretcher courses are in line with each other. A bigger brick makes for a thicker and thus more insulating wall. Historically, this meant that bigger bricks were necessary in colder climates, while a smaller brick was adequate and more economical in warmer regions. A notable illustration of this correlation is the Green Gate 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 specialised insulation materials. In England, the length and width of the common brick remained fairly constant from 1625 when the size was regulated by statute at 9 by 4.5 by 3 inches, but the depth has varied from about 2.5 inches or smaller in earlier times to about 3.5 inches more recently. In the United Kingdom, the usual size of a modern brick from 1965 is 215 by 102.5 by 65 millimeters, which, with a nominal 10 millimeter mortar joint, forms a unit size of 225 by 112.5 by 75 millimeters, for a ratio of 6:3:2.
The Decline And The Red University
Starting in the 20th century, the use of brickwork declined in some areas due to concerns about earthquakes. Earthquakes such as the San Francisco earthquake of 1906 and the 1933 Long Beach earthquake revealed the weaknesses of unreinforced brick masonry in earthquake-prone areas. During seismic events, the mortar cracks and crumbles, so that the bricks are no longer held together. Brick masonry with steel reinforcement, which helps hold the masonry together during earthquakes, has been used to replace unreinforced bricks in many buildings. Retrofitting older unreinforced masonry structures has been mandated in many jurisdictions. However, similar to steel corrosion in reinforced concrete, rebar rusting will compromise the structural integrity of reinforced brick and ultimately limit the expected lifetime, so there is a trade-off between earthquake safety and longevity to a certain extent. In the United States, bricks have been used for both buildings and pavement. Examples of brick use in buildings can be seen in colonial era buildings and other notable structures around the country. Bricks have been used in paving roads and sidewalks especially during the late 19th century and early 20th century. The introduction of asphalt and concrete reduced the use of brick for paving, but they are still sometimes installed as a method of 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, were paved with bricks. 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. In Northwest Europe, bricks have been used in construction for centuries. Until recently, almost all houses were built almost entirely from bricks. Although many houses 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. In the UK a red brick university is one founded in the late 19th or early 20th century. The term is used to refer to such institutions collectively to distinguish them from the older Oxbridge institutions, and refers to the use of bricks, as opposed to stone, in their buildings. Colombian architect Rogelio Salmona was noted for his extensive use of red bricks in his buildings and for using natural shapes like spirals, radial geometry and curves in his designs.