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A brick is a block of ceramic material used in masonry construction and sized to be laid with one hand using mortar.
The oldest shaped bricks found date back to 7,500 B.C. They have been found in Çayönü, a place located in the upper Tigris area, and in south east Anatolia close to Diyarbakir. Other more recent findings, dated between 7,000 and 6,395 B.C., come from Jericho and Catal Hüyük. From archaeological evidence, the invention of the fired brick (as opposed to the considerably earlier sun-dried mud brick) is believed to have arisen in about the third millennium BC in the Middle East. Being much more resistant to cold and moist weather conditions, brick enabled the construction of permanent buildings in regions where the harsher climate precluded the use of mud bricks.
By 1200 AD brick making was to be found across Europe and Asia, from the Atlantic to the Pacific. In the Near East and India, bricks have been in use for more than five thousand years. The plain of the Tigris-Euphrates lacks rocks and trees. Sumerian structures were thus built of plano-convex mudbricks, not fixed with mortar or with cement. As plano-convex bricks (being rounded) are somewhat unstable in behaviour, Sumerian bricklayers would lay a row of bricks perpendicular to the rest every few rows. They would fill the gaps with bitumen, straw, marsh reeds, and weeds.
The Ancient Egyptians and the Indus Valley Civilization also used mudbrick extensively, as can be seen in the ruins of Buhen, Mohenjo-daro and Harappa, for example. In the Indus Valley Civilization all bricks corresponded to sizes in a perfect ratio of 4:2:1.
In Sumerian times offerings of food and drink were presented to "the Bone god," who was "represented in the ritual by the first brick." More recently, mortar for the foundations of the Hagia Sophia in Istanbul was mixed with "a broth of barley and bark of elm" and sacred relics, accompanied by prayers, placed between every 12 bricks.
The Romans made use of fired bricks, and the Roman legions, which operated mobile kilns, introduced bricks to many parts of the empire. Roman bricks are often stamped with the mark of the legion that supervised its production. The use of bricks in Southern and Western Germany, for example, can be traced back to traditions already described by the Roman architect Vitruvius.
In pre-modern China, brick-making was the job of a lowly and unskilled artisan, but a kilnmaster was respected as a step above the latter. Early descriptions of the production process and glazing techniques used for bricks can be found in the Song Dynasty carpenter's manual Yingzao Fashi, 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 writes of the production process in Ming Dynasty China (aided with visual illustrations from the Tiangong Kaiwu 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 color 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 centimeters long, 20 centimeters wide, and 10 centimeters 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 one's name on one's work and signifying the place where the product was made—in this case, bricks—was nothing new to the Ming era and had little or nothing to do with vanity.As far back as the Qin Dynasty (221 BC–206 BC), the government required blacksmiths and weapon-makers to engrave their names onto weapons in order to trace the weapon back to them, lest their weapons should prove to be of a lower quality than the standard required by the government.
In the 12th century, bricks from Northern Italy were re-introduced to Northern Germany, where an independent tradition evolved. It culminated in the so-called brick Gothic, a reduced style of Gothic architecture that flourished in Northern Europe, especially in the regions around the Baltic Sea which are without natural rock resources. Brick Gothic buildings, which are built almost exclusively of bricks, are to be found in Denmark, Germany, Poland and Russia.
During the Renaissance and the Baroque, visible brick walls were unpopular and the brickwork was often covered with plaster. 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, for example.
The transport in bulk of building materials such as paper over long distances was rare before the age of canals, railways, roads and heavy goods vehicles. Before this time bricks were generally made as close as possible to their point of intended use. It has been estimated that in England in the eighteenth 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, even in areas where stone was available, for reasons of speed and economy. The buildings of the Industrial Revolution in Britain were largely constructed of brick and timber due to the unprecedented demand created. Again, during the building boom of the nineteenth century in the eastern seaboard cities of Boston and New York, for example, locally made bricks were often used in construction in preference to the brownstones of New Jersey and Connecticut for these reasons.
The trend of building upwards for offices that emerged towards the end of the 19th century displaced brick in favor of cast and wrought iron and later steel and concrete. Some early 'skyscrapers' were made in masonry, and demonstrated the limitations of the material - for example, the Monadnock Building in Chicago (opened in 1896) is masonry and just sixteen stories high, the ground walls are almost 1.8 meters 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 and the Building Research Establishment in Watford, UK. This method produced eighteen 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-loadbearing walls.
Bricks may be made from clay, shale, soft slate, calcium silicate, concrete, or shaped from quarried stone.
Clay is the most common material, with modern clay bricks formed in one of three processes - soft mud, dry press, or extruded.
In 2007 a new type of brick was invented, based on fly ash, a by-product of coal power plants.
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 press. The shaped clay is then fired ("burned") at 900-1000 °C to achieve strength.
In Pakistan and India, 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 1800s.
An oval or circular trench, 6-9 meters wide, 2-2.5 meters deep, and 100-150 meters in circumference, is dug in a suitable location. A tall exhaust chimney is constructed in the center. 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 while cooled finished bricks are removed from the other end for transport. In the middle the brickworkers create a firing zone by dropping fuel (coal, wood, oil, debris, etc) 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 a considerable 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.
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.
In extruded bricks the clay mix is 20-25% water, this is forced through a die 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 hard dense bricks result, and holes or other perforations can be produced by the die. The introduction of holes reduces the needed volume of clay through the whole process, with the consequent reduction in cost. The bricks are lighter and easier to handle, and have thermal properties different from solid bricks. The cut bricks are hardened by drying for between 20 and 40 hours at 50-150 °C before being fired. The heat for drying is often waste heat from the kiln.
The raw materials for calcium silicate bricks include lime mixed with quartz, crushed flint or crushed siliceous rock together with mineral colorants. 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 two or three 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 brick-layer). The bricks can be made in a variety of colours, white is common but a wide range of "pastel" shades can be achieved..
In May 2007, Henry Liu, 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. 
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 however 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.
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.
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.
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.
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). 
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. 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.
|Density of EPS||25-200 kg/m³|
|Electrical conductivity (s)||10-16 S/m|
|Thermal conductivity (k)||0.08 W/(m·K)|
|Young's modulus (E)||3000-3600 MPa|
|Tensile strength (st)||46–60 MPa|
|Elongation at break||3–4%|
|Notch test||2–5 kJ/m²|
|Glass temperature||95 °C|
|Melting point||240 °C|
|Vicat B||90 °C|
|Heat transfer coefficient(Q)||0.17 W/(m2K)|
|Linear expansion coefficient (a)||8 10-5 /K|
|Specific heat (c)||1.3 kJ/(kg·K)|
|Water absorption (ASTM)||0.03–0.1|
|Decomposition||X years, still decaying|
Polystyrene IPA: /?p?li?sta?ri?n/ is an aromatic polymer made from the aromatic monomer styrene, a liquid hydrocarbon that is commercially manufactured from petroleum by the chemical industry. Polystyrene is a thermoplastic substance, normally existing in solid state at room temperature, but melting if heated (for molding or extrusion), and becoming solid again when cooling off.
Pure solid polystyrene is a colorless, hard plastic with limited flexibility. It can be cast into molds with fine detail. Polystyrene can be transparent or can be made to take on various colours. It is economical and is used for producing plastic model assembly kits, license plate frames, plastic cutlery, CD "jewel" cases, and many other objects where a fairly rigid, economical plastic is desired.
Polystyrene was discovered in 1839 by Eduard Simon, an apothecary in Berlin. From storax, the resin of Liquidambar orientalis, he distilled an oily substance, a monomer which he named styrol. Several days later Simon found that the styrol had thickened, presumably from oxidation, into a jelly he dubbed styrol oxide ("Styroloxyd"). By 1845 English chemist John Blyth and German chemist August Wilhelm von Hofmann showed that the same transformationof styrol took place in the absence of oxygen. They called their substance metastyrol. Analysis later showed that it was chemically identical to Styroloxyd. In 1866 Marcelin Berthelot correctly identified the formation of metastyrol from styrol as a polymerization process. About 80 years went by before it was realized that heating of styrol starts a chain reaction which produces macromolecules, following the thesis of German organic chemist Hermann Staudinger (1881–1965). This eventually led to the substancereceiving its present name, polystyrene. The I. G. Farben company began manufacturing polystyrene in Ludwigshafen, Germany, about 1931, hoping it would be a suitable replacement for die cast zinc in many applications. Success was achieved when they developed a reactor vessel that extruded polystyrene through a heated tube and cutter, producing polystyrene in pellet form.
The chemical makeup of polystyrene is a long chain hydrocarbon with every other carbon connected to a Phenyl group (the name given to the aromatic ring benzene, when bonded to complex carbon substituents).
A 3-D model would show that each of the chiral backbone carbons lies at the center of a tetrahedron, with its 4 bonds pointing toward the vertices. Say the -C-C- bonds are rotated so that the backbone chain lies entirely in the plane of the diagram. From this flat schematic, it is not evident which of the phenyl (benzene) groups are angled toward us from the plane of the diagram, and which ones are angled away. The isomer where all of them are on the same side is called isotactic polystyrene,which is not produced commercially. Ordinary atactic polystyrene has these large phenyl groups randomly distributed on both sides of the chain. This random positioning prevents the chains from ever aligning with sufficient regularity to achieve any crystallinity, so the plastic has no melting temperature, Tm. But metallocene-catalyzed polymerization can produce an ordered syndiotactic polystyrene with the phenyl groups on alternating sides. This form is highly crystalline witha Tm of 270 °C.
Polystyrene's most common use is as expanded polystyrene (EPS). Expanded polystyrene is produced from a mixture of about 90-95% polystyrene and 5-10% gaseous blowing agent, most commonly pentane or carbon dioxide. The solid plastic is expanded into a foam through the use of heat, usually steam.
Extruded polystyrene (XPS), which is different from expanded polystyrene (EPS), is commonly known by the trade name Styrofoam. The voids filled with trapped air give it low thermal conductivity. This makes it ideal as a construction material and it is therefore sometimes used in structural insulated panel building systems. It is also used as insulation in building structures, as molded packing material for cushioning fragile equipment inside boxes, as packing "peanuts", as non-weight-bearingarchitectural structures (such as pillars), and also in crafts and model building, particularly architectural models. Foamed between two sheets of paper, it makes a more-uniform substitute for corrugated cardboard, tradenamed Fome-Cor. A more unexpected use for the material is as a lightweight fill for embankments in the civil engineering industry .
Expanded polystyrene used to contain CFCs, but other, more environmentally-safe blowing agents are now used. Because it is an aromatic hydrocarbon, it burns with an orange-yellow flame, giving off soot, as opposed to non-aromatic hydrocarbon polymers such as polyethylene, which burn with a light yellow flame (often with a blue tinge) and no soot.
Production methods include sheet stamping (PS) and injection molding(both PS and HIPS).
The density of expanded polystyrene varies greatly from around 25 kg/m³ to 200 kg/m³ depending on how much gas was admixed to create the foam. A density of 200 kg/m³ is typical for the expanded polystyrene used in surfboards.
The resin identification code symbol for polystyrene, developed by the Society of the Plastics Industry so that items can be labeled for easy recycling, is . However, the majority of polystyrene products are currently not recycled because of a lack of suitable recycling facilities. Furthermore, when it is "recycled," it is not a closed loop — polystyrene cups and other packaging materials are usually recycled into fillers in other plastics, or other items that cannot themselves be recycled and are thrown away.
Acrylonitrile butadiene styreneor ABS plastic is similar to HIPS: a copolymer of acrylonitrile and styrene, toughened with polybutadiene. Most electronics cases are made of this form of polystyrene, as are many sewer pipes. ABS pipes may become brittle over time. SAN is a copolymer of styrene with acrylonitrile.
Styrene can be copolymerized with other monomers; for example, divinylbenzene for cross-linking the polystyrene chains.
Expanded polystyrene is very easily cut with a hot-wire foam cutter, which is easily made by a heated taut length of wire, usually nichrome because of nichrome's resistance to oxidation at high temperatures and its suitable electrical conductivity. The hot wire foam cutter works by heating the wire to the point where it can vaporize foam immediately adjacent to it. The foam gets vaporized before actually touching the heated wire, which yields exceptionally smooth cuts.
Polystyrene, shaped and cut with hot wire foam cutters, is used in architecture models, actual signage, amusement parks, movie sets, airplane construction, and much more. Such cutters may cost just a few dollars (for a completely manual cutter) to tens of thousands of dollars for large CNCmachines that can be used in high-volume industrial production.
Polystyrene can also be cut with a traditional cutter. In order to do this without ruining the sides of the blade one must first dip the blade in water and cut with the blade at an angle of about 30º. The procedure has to be repeated multiple times for best results.
Polystyrene can also be cut on 3 and 5-axis routers, enabling large-scale prototyping and model-making. Special polystyrene cutters are available that look more like large cylindrical rasps.
Manufacture of stone wool
Stone wool is a furnace product of molten stone, at a temperature of about 1600°C, through which is blown a stream of air or steam. More high tech production techniques are based on spinning molten rock (lava) on high speed spinning wheels. (compare with candy floss) The final product is a mass of fine intertwined fibres with a typical diameter of 6 to 10 micrometres. Mineral wool may contain a binder and an oil to reduce dusting and making it water repellent (hydrophobic).
The fibres themselves are excellent conductors of heat, but they package air so well, that when pressed into rolls and sheets, rockwool makes for an excellent and reliable insulator. Batts, sheets and roll made of rockwool are a poor conductor of heat and sound. Fire resistive properties for mineral wools is given here in descending order:
No conventional building materials, including mineral wool are immune to the effects of fire of sufficient duration or intensity. However, each of the aforementioned three wools make common components in passive fire protection systems, such as in spray fireproofing, stud cavities in drywall assemblies required to have a fire-resistance rating, packing materials in firestops and more.
Mineral wools are unattractive to rodents but will provide a structure for bacterial growth if allowed to become wet.
Other uses are in resin bonded panels, growth medium in hydroponics, filler in compounds for gaskets, brake pads, in plastics in the automotive industry and as a filtering medium.
( from: Wikipedia )
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