1.
Concrete
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Concrete is a composite material composed of coarse aggregate bonded together with a fluid cement that hardens over time. Most concretes used are lime-based concretes such as Portland cement concrete or concretes made with other hydraulic cements, when aggregate is mixed together with dry Portland cement and water, the mixture forms a fluid slurry that is easily poured and molded into shape. The cement reacts chemically with the water and other ingredients to form a matrix that binds the materials together into a durable stone-like material that has many uses. Often, additives are included in the mixture to improve the properties of the wet mix or the finished material. Most concrete is poured with reinforcing materials embedded to provide tensile strength, famous concrete structures include the Hoover Dam, the Panama Canal, and the Roman Pantheon. The earliest large-scale users of technology were the ancient Romans. The Colosseum in Rome was built largely of concrete, and the dome of the Pantheon is the worlds largest unreinforced concrete dome. Today, large concrete structures are made with reinforced concrete. After the Roman Empire collapsed, use of concrete became rare until the technology was redeveloped in the mid-18th century, today, concrete is the most widely used man-made material. The word concrete comes from the Latin word concretus, the passive participle of concrescere, from con-. Perhaps the earliest known occurrence of cement was twelve years ago. A deposit of cement was formed after an occurrence of oil shale located adjacent to a bed of limestone burned due to natural causes and these ancient deposits were investigated in the 1960s and 1970s. On a human timescale, small usages of concrete go back for thousands of years and they discovered the advantages of hydraulic lime, with some self-cementing properties, by 700 BC. They built kilns to supply mortar for the construction of houses, concrete floors. The cisterns were kept secret and were one of the reasons the Nabataea were able to thrive in the desert, some of these structures survive to this day. In the Ancient Egyptian and later Roman eras, it was re-discovered that adding volcanic ash to the mix allowed it to set underwater, similarly, the Romans knew that adding horse hair made concrete less liable to crack while it hardened, and adding blood made it more frost-resistant. Crystallization of strätlingite and the introduction of pyroclastic clays creates further fracture resistance, german archaeologist Heinrich Schliemann found concrete floors, which were made of lime and pebbles, in the royal palace of Tiryns, Greece, which dates roughly to 1400–1200 BC. Lime mortars were used in Greece, Crete, and Cyprus in 800 BC, the Assyrian Jerwan Aqueduct made use of waterproof concrete
2.
Mortar (masonry)
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In its broadest sense mortar includes pitch, asphalt, and soft mud or clay, such as used between mud bricks. Mortar comes from Latin mortarium meaning crushed, mortars are typically made from a mixture of sand, a binder, and water. The most common binder since the early 20th century is Portland cement, there are several types of cement mortars and additives. The first mortars were made of mud and clay, because of a lack of stone and an abundance of clay, Babylonian constructions were of baked brick, using lime or pitch for mortar. According to Roman Ghirshman, the first evidence of using a form of mortar was at the Mehrgarh of Baluchistan in Pakistan. The ancient sites of Harappan civilization of third millennium BCE are built with kiln-fired bricks, gypsum mortar, also called plaster of Paris, was used in the construction of the Egyptian pyramids and many other ancient structures. It is made from gypsum, which requires a firing temperature. It is therefore easier to make lime mortar and sets up much faster which may be a reason it was used as the typical mortar in ancient, brick arch. Gypsum mortar is not as durable as other mortars in damp conditions, in early Egyptian pyramids, which were constructed during the Old Kingdom, the limestone blocks were bound by mortar of mud and clay, or clay and sand. In later Egyptian pyramids, the mortar was made of gypsum or lime. Gypsum mortar was essentially a mixture of plaster and sand and was quite soft, in the Indian subcontinent, multiple cement types have been observed in the sites of the Indus Valley Civilization, such as the Mohenjo-daro city-settlement that dates to earlier than 2600 BCE. Bitumen mortar was used at a lower-frequency, including in the Great Bath at Mohenjo-daro. Historically, building with concrete and mortar next appeared in Greece, the excavation of the underground aqueduct of Megara revealed that a reservoir was coated with a pozzolanic mortar 12 mm thick. This aqueduct dates back to c.500 BCE, pozzolanic mortar is a lime based mortar, but is made with an additive of volcanic ash that allows it to be hardened underwater, thus it is known as hydraulic cement. The Greeks obtained the volcanic ash from the Greek islands Thira and Nisiros, or from the then Greek colony of Dicaearchia near Naples, the Romans later improved the use and methods of making what became known as pozzolanic mortar and cement. Even later, the Romans used a mortar without pozzolana using crushed terra cotta, introducing aluminum oxide and this mortar was not as strong as pozzolanic mortar, but, because it was denser, it better resisted penetration by water. Hydraulic mortar was not available in ancient China, possibly due to a lack of volcanic ash, around 500 CE, sticky rice soup was mixed with slaked lime to make an inorganic−organic composite mortar that had more strength and water resistance than lime mortar. It is not understood how the art of making hydraulic mortar and cement, during the Middle Ages when the Gothic cathedrals were being built, the only active ingredient in the mortar was lime
3.
Construction aggregate
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Aggregates are the most mined materials in the world. Aggregates are a component of composite materials such as concrete and asphalt concrete, aggregates are also used as base material under foundations, roads, and railroads. Preferred bitumenous aggregate sizes for road construction are given in EN13043 as d/D, the same classification sizing is used for larger armour stone sizes in EN13383, EN12620 for concrete aggregate, EN13242 for base layers of road construction and EN13450 for railway ballast. These products include specific types of coarse and fine aggregate designed for such uses as additives to asphalt and concrete mixes, state transportation departments further refine aggregate material specifications in order to tailor aggregate use to the needs and available supply in their particular locations. In addition, there are materials that are used as specialty lightweight aggregates, clay, pumice, perlite. People have used sand and stone for foundations for thousands of years, significant refinement of the production and use of aggregate occurred during the Roman Empire, which used aggregate to build its vast network of roads and aqueducts. The invention of concrete, which was essential to architecture utilizing arches, created an immediate, vitruvius writes in De architectura, Economy denotes the proper management of materials and of site, as well as a thrifty balancing of cost and common sense in the construction of works. This will be observed if, in the first place, the architect does not demand things which cannot be found or made ready without great expense, for example, it is not everywhere that there is plenty of pit-sand, rubble, fir, clear fir, and marble. Where there is no pit sand, we must use the kinds washed up by rivers or by the sea. the advent of modern blasting methods enabled the development of quarries, which are now used throughout the world, wherever competent bedrock deposits of aggregate quality exist. In many places, good limestone, granite, marble or other quality stone bedrock deposits do not exist, in these areas, natural sand and gravel are mined for use as aggregate. Where neither stone, nor sand and gravel, are available, construction demand is satisfied by shipping in aggregate by rail. Additionally, demand for aggregates can be satisfied through the use of slag. However, the available tonnages and lesser quality of these materials prevent them from being a replacement for mined aggregates on a large scale. Large stone quarry and sand and gravel operations exist near virtually all population centers, limestone and granite are also produced in large amounts as dimension stone. The great majority of crushed stone is moved by truck from the quarry/plant to the first point of sale or use. According to the USGS,2006 U. S. sand and gravel production was 1.32 billion tonnes valued at $8.54 billion, the great majority of this was again moved by truck, instead of by electric train. Currently, total U. S. aggregate demand by final market sector was 30%–35% for non-residential building, 25% for highways, the largest-volume of recycled material used as construction aggregate is blast furnace and steel furnace slag. Blast furnace slag is either air-cooled or granulated, if the granulated blast furnace slag accesses free lime during hydration, it develops strong hydraulic cementitious properties and can partly substitute for portland cement in concrete
4.
Lime (material)
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Lime is a calcium-containing inorganic material in which carbonates, oxides, and hydroxides predominate. In the strict sense of the term, lime is calcium oxide or calcium hydroxide and it is also the name of the natural mineral CaO which occurs as a product of coal seam fires and in altered limestone xenoliths in volcanic ejecta. The word lime originates with its earliest use as building mortar and has the sense of sticking or adhering and these materials are still used in large quantities as building and engineering materials, as chemical feedstocks, and for sugar refining, among other uses. Lime industries and the use of many of the resulting products date from prehistoric times in both the Old World and the New World, Lime is used extensively for wastewater treatment with ferrous sulfate. The rocks and minerals from which these materials are derived, typically limestone or chalk, are composed primarily of calcium carbonate and they may be cut, crushed or pulverized and chemically altered. Lime kilns are the used for lime burning and slaking. When the term is encountered in a context, it usually refers to agricultural lime. Otherwise it most commonly means slaked lime, as the dangerous form is usually described more specifically as quicklime or burnt lime. In the lime industry, limestone is a term for rocks that contain 80% or more of calcium or magnesium carbonates, including marble, chalk, oolite. Further classification is by composition as high calcium, argillaceous, silicious, conglomerate, magnesian, dolomite, uncommon sources of lime include coral, sea shells, calcite, and ankerite. Limestone is extracted from quarries or mines, dry slaking is when quicklime is slaked with just enough water to hydrate the quicklime, but remain as a powder and is referred to as hydrated lime. In wet slaking, enough water, but not too much, is added to hydrate the quicklime to a referred to as lime putty. Because lime has a property with bricks and stones, it is often used as binding material in masonry works. It is also used in whitewashing as wall coat to adhere the whitewash onto the wall, the process by which limestone is converted to quicklime by heating, then to slaked lime by hydration, and naturally reverts to calcium carbonate by carbonation is called the lime cycle. The conditions and compounds present during each step of the cycle have a strong influence of the end product, thus the complex. An example is when slaked lime is mixed into a slurry with sand. When the masonry has been laid, the lime in the mortar slowly begins to react with carbon dioxide to form calcium carbonate according to the reaction. The carbon dioxide that takes part in reaction is principally available in the air or dissolved in rainwater so pure lime mortar will not recarbonate under water or inside a thick masonry wall
5.
Portland cement
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Portland cement is the most common type of cement in general use around the world, used as a basic ingredient of concrete, mortar, stucco, and most non-speciality grout. It was developed from other types of lime in England in the mid 19th century. It is a fine powder produced by heating materials in a kiln to form what is called clinker, grinding the clinker, and adding small amounts of other materials. Several types of Portland cement are available, with the most common being called ordinary Portland cement which is grey in color, Portland cement is caustic, so it can cause chemical burns. The powder can cause irritation or, with exposure, lung cancer and can contain some hazardous components such as crystalline silica. Concrete produced from Portland cement is one of the most versatile construction materials available in the world, Portland cement was developed from natural cements made in Britain beginning in the middle of the 18th century. Its name is derived from its similarity to Portland stone, a type of building stone quarried on the Isle of Portland in Dorset, England. In the late 18th century, Roman cement was developed and patented in 1796 by James Parker, Roman cement quickly became popular, in 1811 James Frost produced a cement he called British cement. James Frost is reported to have erected a manufactory for making of an artificial cement in 1826, in 1843, Aspdins son William improved their cement, which was initially called Patent Portland cement, although he had no patent. In 1818, French engineer Louis Vicat invented a hydraulic lime considered the principal forerunner of Portland cement. Edgar Dobbs of Southwark patented a cement of this kind in 1811, Portland cement was used by Joseph Aspdin in his cement patent in 1824 because of the cements resemblance to Portland stone. The name Portland cement is also recorded in a directory published in 1823 being associated with a William Lockwood, a Dave Stewart, however, Aspdins cement was nothing like modern Portland cement but was a first step in the development of modern Portland cement, called a proto-Portland cement. William Aspdin had left his fathers company and in his cement manufacturing apparently accidentally produced calcium silicates in the 1840s, in 1848, William Aspdin further improved his cement, in 1853, he moved to Germany, where he was involved in cement making. William Aspdin made what could be called meso-Portland cement, isaac Charles Johnson further refined the production of meso-Portland cement and claimed to be the real father of Portland cement. John Grant of the Metropolitan Board of Works in 1859 set out requirements for cement to be used in the London sewer project and this became a specification for Portland cement. The Hoffman endless kiln which gave control over combustion was tested in 1860. This cement was made at the Portland Cementfabrik Stern at Stettin and it is thought that the first modern Portland cement was made there. The Association of German Cement Manufacturers issued a standard on Portland cement in 1878, by the early 20th century American-made Portland cement had displaced most of the imported Portland cement
6.
Adhesive
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The use of adhesives offers many advantages over binding techniques such as sewing, mechanical fastening, thermal bonding, etc. Adhesives are typically organized by the method of adhesion and these are then organized into reactive and non-reactive adhesives, which refers to whether the adhesive chemically reacts in order to harden. Alternatively they can be organized by whether the raw stock is of natural or synthetic origin, Adhesives may be found naturally or produced synthetically. The earliest human use of substances was approximately 200,000 years ago. The first references to adhesives in literature first appeared in approximately 2000 BCE, the Greeks and Romans made great contributions to the development of adhesives. In Europe, glue was not widely used until the period 1500–1700 CE, from then until the 1900s increases in adhesive use and discovery were relatively gradual. Only since the last century has the development of synthetic adhesives accelerated rapidly, the earliest use of adhesives was discovered in central Italy when two stone flakes partially covered with birch-bark tar and a third uncovered stone from the Middle Pleistocene era were found. This is thought to be the oldest discovered human use of tar-hafted stones, the birch-bark-tar adhesive is a simple, one-component adhesive. Although sticky enough, plant-based adhesives are brittle and vulnerable to environmental conditions, the first use of compound adhesives was discovered in Sibudu, South Africa. The ability to produce stronger adhesives allowed middle stone age humans to attach stone segments to sticks in greater variations, more recent examples of adhesive use by prehistoric humans have been found at the burial sites of ancient tribes. Archaeologists studying the sites found that approximately 6,000 years ago the tribesmen had buried their dead together with food found in clay pots repaired with tree resins. The glue was analyzed as pitch, which requires the heating of tar during its production, the retrieval of this tar requires a transformation of birch bark by means of heat, in a process known as pyrolysis. The first references to adhesives in literature first appeared in approximately 2000 BCE, further historical records of adhesive use are found from the period spanning 1500–1000 BCE. Artifacts from this period include paintings depicting wood gluing operations and a made of wood. Other ancient Egyptian artifacts employ animal glue for bonding or lamination, such lamination of wood for bows and furniture is thought to have extended their life and was accomplished using casein -based glues. The ancient Egyptians also developed starch-based pastes for the bonding of papyrus to clothing, from 1 to 500 AD the Greeks and Romans made great contributions to the development of adhesives. Wood veneering and marquetry were developed, the production of animal and fish glues refined, egg-based pastes were used to bond gold leaves incorporated various natural ingredients such as blood, bone, hide, milk, cheese, vegetables, and grains. The Greeks began the use of slaked lime as mortar while the Romans furthered mortar development by mixing lime with volcanic ash and this material, known as pozzolanic cement, was used in the construction of the Roman Colosseum and Pantheon
7.
Chemical reaction
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A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Nuclear chemistry is a sub-discipline of chemistry that involves the reactions of unstable. The substance initially involved in a reaction are called reactants or reagents. Chemical reactions are characterized by a chemical change, and they yield one or more products. Reactions often consist of a sequence of individual sub-steps, the elementary reactions. Chemical reactions are described with chemical equations, which present the starting materials, end products. Chemical reactions happen at a characteristic reaction rate at a given temperature, typically, reaction rates increase with increasing temperature because there is more thermal energy available to reach the activation energy necessary for breaking bonds between atoms. Reactions may proceed in the forward or reverse direction until they go to completion or reach equilibrium, Reactions that proceed in the forward direction to approach equilibrium are often described as spontaneous, requiring no input of free energy to go forward. Non-spontaneous reactions require input of energy to go forward. Different chemical reactions are used in combinations during chemical synthesis in order to obtain a desired product, in biochemistry, a consecutive series of chemical reactions form metabolic pathways. These reactions are catalyzed by protein enzymes. Chemical reactions such as combustion in fire, fermentation and the reduction of ores to metals were known since antiquity, in the Middle Ages, chemical transformations were studied by Alchemists. They attempted, in particular, to lead into gold, for which purpose they used reactions of lead. The process involved heating of sulfate and nitrate minerals such as sulfate, alum. In the 17th century, Johann Rudolph Glauber produced hydrochloric acid and sodium sulfate by reacting sulfuric acid, further optimization of sulfuric acid technology resulted in the contact process in the 1880s, and the Haber process was developed in 1909–1910 for ammonia synthesis. From the 16th century, researchers including Jan Baptist van Helmont, Robert Boyle, the phlogiston theory was proposed in 1667 by Johann Joachim Becher. It postulated the existence of an element called phlogiston, which was contained within combustible bodies. This proved to be false in 1785 by Antoine Lavoisier who found the explanation of the combustion as reaction with oxygen from the air
8.
Hydrate
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In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was understood, in organic chemistry, a hydrate is a compound formed by the addition of water or its elements to another molecule. A molecule of water may be eliminated, for example by the action of sulfuric acid, another example is chloral hydrate, CCl3–CH2, which can be formed by reaction of water with chloral, CCl3–CH=O. Many organic molecules, as well as molecules, form crystals that incorporate water into the crystalline structure without chemical alteration of the organic molecule. The sugar trehalose, for example, exists in both a form and as a dihydrate. Protein crystals commonly have as much as 50% water content, molecules are also labeled as hydrates for historical reasons not covered above. Glucose, C6H12O6, was thought of as C66 and described as a carbohydrate. Methanol is often sold as methyl hydrate, implying the incorrect formula CH3OH2, such hydrates are also said to contain water of crystallization or water of hydration. If the water is water, where the hydrogen involved is the isotope deuterium. A colorful example is cobalt chloride, which turns blue to red upon hydration. The notation hydrated compound⋅nH2O, where n is the number of molecules per formula unit of the salt, is commonly used to show that a salt is hydrated. The n is usually a low integer, though it is possible for fractional values to occur, for example, in a monohydrate n is one, and in a hexahydrate n is 6. Numerical prefixes of Greek origin are, A hydrate which has lost water is referred to as an anhydride, a substance that does not contain any water is referred to as anhydrous. Some anhydrous compounds are hydrated so easily that they are said to be hygroscopic and are used as drying agents or desiccants, clathrate hydrates are water ice with gas molecules trapped within, they are a form of clathrate. An important example is methane hydrate, nonpolar molecules such as methane can form clathrate hydrates with water, especially under high pressure. In such cases the guest-host hydrogen bonds result in the formation of L-type Bjerrum defects in the clathrate lattice, the stability of hydrates is generally determined by the nature of the compounds, their temperature, and the relative humidity
9.
Volcanic ash
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Volcanic ash consists of fragments of pulverized rock, minerals and volcanic glass, created during volcanic eruptions and measuring less than 2 mm in diameter. The term volcanic ash is often loosely used to refer to all explosive eruption products. Volcanic ash is formed during volcanic eruptions when dissolved gases in magma expand. The force of the escaping gas shatters the magma and propels it into the atmosphere where it solidifies into fragments of volcanic rock and glass. Ash is also produced when magma comes into contact with water during phreatomagmatic eruptions, once in the air, ash is transported by wind up to thousands of kilometers away. Volcanic ash is formed during volcanic eruptions, phreatomagmatic eruptions. Explosive eruptions occur when magma decompresses as it rises, allowing dissolved volatiles to exsolve into gas bubbles, as more bubbles nucleate a foam is produced, which decreases the density of the magma, accelerating it up the conduit. Fragmentation occurs when bubbles occupy ~70-80 vol% of the erupting mixture, when fragmentation occurs, violently expanding bubbles tear the magma apart into fragments which are ejected into the atmosphere where they solidify into ash particles. Fragmentation is an efficient process of ash formation and is capable of generating very fine ash even without the addition of water. Volcanic ash is produced during phreatomagmatic eruptions. During these eruptions fragmentation occurs when magma comes into contact with bodies of water groundwater, as the magma, which is significantly hotter than the boiling point of water, comes into contact with water an insulating vapor film forms. Eventually this vapor film will collapse leading to direct coupling of the cold water and this increases the heat transfer which leads to the rapid expansion of water and fragmentation of the magma into small particles which are subsequently ejected from the volcanic vent. Fragmentation causes an increase in area between magma and water creating a feedback mechanism, leading to further fragmentation and production of fine ash particles. Pyroclastic density currents can also produce ash particles and these are typically produced by lava dome collapse or collapse of the eruption column. Within pyroclastic density currents particle abrasion occurs as particles interact with each resulting in a reduction in grain size. In addition, ash can be produced during secondary fragmentation of pumice fragments and these processes produce large quantities of very fine grained ash which is removed from pyroclastic density currents in co-ignimbrite ash plumes. Physical and chemical characteristics of volcanic ash are primarily controlled by the style of volcanic eruption, another parameter controlling the amount of ash produced is the duration of the eruption, the longer the eruption is sustained, the more ash will be produced. The types of minerals present in volcanic ash are dependent on the chemistry of the magma from which it erupted, low energy eruptions of basalt produce a characteristically dark coloured ash containing ~45 - 55% silica that is generally rich in iron and magnesium
10.
Ancient Rome
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In its many centuries of existence, the Roman state evolved from a monarchy to a classical republic and then to an increasingly autocratic empire. Through conquest and assimilation, it came to dominate the Mediterranean region and then Western Europe, Asia Minor, North Africa and it is often grouped into classical antiquity together with ancient Greece, and their similar cultures and societies are known as the Greco-Roman world. Ancient Roman civilisation has contributed to modern government, law, politics, engineering, art, literature, architecture, technology, warfare, religion, language and society. Rome professionalised and expanded its military and created a system of government called res publica, the inspiration for modern republics such as the United States and France. By the end of the Republic, Rome had conquered the lands around the Mediterranean and beyond, its domain extended from the Atlantic to Arabia, the Roman Empire emerged with the end of the Republic and the dictatorship of Augustus Caesar. 721 years of Roman-Persian Wars started in 92 BC with their first war against Parthia and it would become the longest conflict in human history, and have major lasting effects and consequences for both empires. Under Trajan, the Empire reached its territorial peak, Republican mores and traditions started to decline during the imperial period, with civil wars becoming a prelude common to the rise of a new emperor. Splinter states, such as the Palmyrene Empire, would divide the Empire during the crisis of the 3rd century. Plagued by internal instability and attacked by various migrating peoples, the part of the empire broke up into independent kingdoms in the 5th century. This splintering is a landmark historians use to divide the ancient period of history from the pre-medieval Dark Ages of Europe. King Numitor was deposed from his throne by his brother, Amulius, while Numitors daughter, Rhea Silvia, because Rhea Silvia was raped and impregnated by Mars, the Roman god of war, the twins were considered half-divine. The new king, Amulius, feared Romulus and Remus would take back the throne, a she-wolf saved and raised them, and when they were old enough, they returned the throne of Alba Longa to Numitor. Romulus became the source of the citys name, in order to attract people to the city, Rome became a sanctuary for the indigent, exiled, and unwanted. This caused a problem for Rome, which had a large workforce but was bereft of women, Romulus traveled to the neighboring towns and tribes and attempted to secure marriage rights, but as Rome was so full of undesirables they all refused. Legend says that the Latins invited the Sabines to a festival and stole their unmarried maidens, leading to the integration of the Latins, after a long time in rough seas, they landed at the banks of the Tiber River. Not long after they landed, the men wanted to take to the sea again, one woman, named Roma, suggested that the women burn the ships out at sea to prevent them from leaving. At first, the men were angry with Roma, but they realized that they were in the ideal place to settle. They named the settlement after the woman who torched their ships, the Roman poet Virgil recounted this legend in his classical epic poem the Aeneid
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Roman concrete
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Roman concrete, also called opus caementicium, was a material used in construction during the late Roman Republic until the fading of the Roman Empire. Roman concrete was based on a hydraulic-setting cement, recently, it has been found that it materially differs in several ways from modern concrete which is based on Portland cement. Roman concrete is due to its incorporation of volcanic ash. By the middle of the 1st century, the material was used frequently, often brick-faced, Roman concrete was normally faced with stone or brick, and interiors might be further decorated by stucco, fresco paintings, or thin slabs of fancy colored marbles. Some Roman concretes were able to be set underwater, which was useful for bridges and it is uncertain when Roman concrete was developed, but it was clearly in widespread and customary use from about 150 BC, some scholars believe it was developed a century before that. Vitruvius, writing around 25 BC in his Ten Books on Architecture, for structural mortars, he recommended pozzolana, which are volcanic sands from the sandlike beds of Pozzuoli brownish-yellow-gray in color near Naples and reddish-brown at Rome. By the middle of the 1st century, the principles of construction in concrete were well known to Roman builders. The city of Caesarea was the earliest known example to have use of underwater Roman concrete technology on such a large scale. Rebuilding Rome after the fire in 64 AD, which destroyed portions of the city. This appears to have encouraged the development of the brick and concrete industries, Roman concrete, like any concrete, consists of an aggregate and hydraulic mortar – a binder mixed with water that hardens over time. The aggregate varied, and included pieces of rock, ceramic tile, reinforcing elements, such as steel rebar, were not used. Gypsum and lime were used as binders, volcanic dusts, called pozzolana or pit sand, were favored where they could be obtained. Pozzolana makes the concrete more resistant to water than modern-day concrete. The pozzolanic mortar used had a content of alumina and silica. Tuff was often used as an aggregate, concrete, and in particular, the hydraulic mortar responsible for its cohesion, was a type of structural ceramic whose utility derived largely from its rheological plasticity in the paste state. The setting and hardening of hydraulic cements derived from hydration of materials and this differed from the setting of slaked lime mortars, the most common cements of the pre-Roman world. Once set, Roman concrete exhibited little plasticity, although it retained some resistance to tensile stresses, the setting of pozzolanic cements has much in common with setting of their modern counterpart, Portland cement. The high silica composition of Roman pozzolana cements is very close to that of cement to which blast furnace slag, fly ash
12.
Masonry
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Masonry is the building of structures from individual units, which are often laid in and bound together by mortar, the term masonry can also refer to the units themselves. The common materials of construction are brick, building stone such as marble, granite, travertine, and limestone, cast stone, concrete block, glass block. Masonry is generally a durable form of construction. However, the used, the quality of the mortar and workmanship. A person who constructs masonry is called a mason or bricklayer, Masonry is commonly used for walls and buildings. Brick and concrete block are the most common types of masonry in use in industrialized nations, Concrete blocks, especially those with hollow cores, offer various possibilities in masonry construction. They generally provide great strength, and are best suited to structures with light transverse loading when the cores remain unfilled. Filling some or all of the cores with concrete or concrete with steel reinforcement offers much greater tensile, the use of material such as bricks and stones can increase the thermal mass of a building and can protect the building from fire. Masonry walls are resistant to projectiles, such as debris from hurricanes or tornadoes. Extreme weather, under circumstances, can cause degradation of masonry due to expansion. Masonry tends to be heavy and must be built upon a foundation, such as reinforced concrete. Other than concrete, masonry construction does not lend well to mechanization. Masonry consists of components and has a low tolerance to oscillation as compared to other materials such as reinforced concrete, plastics, wood. Masonry has high compressive strength under vertical loads but has low tensile strength unless reinforced, the tensile strength of masonry walls can be increased by thickening the wall, or by building masonry piers at intervals. Where practical, steel reinforcements such as windposts can be added, a masonry veneer wall consists of masonry units, usually clay-based bricks, installed on one or both sides of a structurally independent wall usually constructed of wood or masonry. In this context the brick masonry is primarily decorative, not structural, the brick veneer is generally connected to the structural wall by brick ties. There is typically an air gap between the veneer and the structural wall. Concrete blocks, real and cultured stones, and veneer adobe are sometimes used in a very similar veneer fashion
13.
Calcium oxide
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Calcium oxide, commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline, crystalline solid at room temperature, the broadly used term lime connotes calcium-containing inorganic materials, in which carbonates, oxides and hydroxides of calcium, silicon, magnesium, aluminium, and iron predominate. By contrast, quicklime specifically applies to the chemical compound calcium oxide. Calcium oxide that survives processing without reacting in building such as cement is called free lime. Both it and a chemical derivative are important commodity chemicals, Calcium oxide is usually made by the thermal decomposition of materials, such as limestone or seashells, that contain calcium carbonate in a lime kiln. This is accomplished by heating the material to above 825 °C, annual worldwide production of quicklime is around 283 million tonnes. China is by far the worlds largest producer, with a total of around 170 million tonnes per year, the United States is the next largest, with around 20 million tonnes per year. Approximately 1.8 t of limestone is required per 1.0 t of quicklime, quicklime has a high affinity for water and is a more efficient desiccant than silica gel. The reaction of quicklime with water is associated with an increase in volume by a factor of at least 2.5, the major use of quicklime is in the Basic oxygen steelmaking process. Its usage varies from about 30–50 kg/t of steel, the quicklime neutralizes the acidic oxides, SiO2, Al2O3, and Fe2O3, to produce a basic molten slag. Ground quicklime is used in the production of aerated concrete blocks, quicklime and hydrated lime can considerably increase the load carrying capacity of clay-containing soils. They do this by reacting with finely divided silica and alumina to produce calcium silicates and aluminates, small quantities of quicklime are used in other processes, e. g. the production of glass, calcium aluminate cement, and organic chemicals. The hydrate can be reconverted to quicklime by removing the water by heating it to redness to reverse the hydration reaction, one litre of water combines with approximately 3.1 kilograms of quicklime to give calcium hydroxide plus 3.54 MJ of energy. This process can be used to provide a convenient portable source of heat, light, When quicklime is heated to 2,400 °C, it emits an intense glow. This form of illumination is known as a limelight, and was used broadly in theatrical productions prior to the invention of electric lighting, cement, Calcium oxide is a key ingredient for the process of making cement. As a cheap and widely available alkali, about 50% of the total quicklime production is converted to calcium hydroxide before use. Both quick- and hydrated lime are used in the treatment of drinking water, petroleum industry, Water detection pastes contain a mix of calcium oxide and phenolphthalein. Should this paste come into contact with water in a storage tank
14.
Brick
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A brick is building material used to make walls, pavements and other elements in masonry construction. Traditionally, the term referred to a unit composed of clay. A brick can be composed of clay-bearing soil, sand, and lime, Bricks are produced in numerous classes, types, materials, and sizes which vary with region and time period, and are produced in bulk quantities. Two basic categories of bricks are fired and non-fired bricks, block is a similar term referring to a rectangular building unit composed of similar materials, but is usually larger than a brick. Lightweight bricks are made from expanded clay aggregate, fired bricks are one of the longest-lasting and strongest building materials, sometimes referred to as artificial stone, and have been used since circa 5000 BC. Air-dried bricks, also known as mudbricks, have an older than fired bricks. Bricks are laid in courses and numerous patterns known as bonds, collectively known as brickwork, the earliest bricks were dried brick, meaning that they were formed from clay-bearing earth or mud and dried until they were strong enough for use. The oldest discovered bricks, originally made from shaped mud and dating before 7500 BC, were found at Tell Aswad, in the upper Tigris region, ceramic, or fired brick was used as early as 3000 BC in early Indus Valley cities. In pre-modern China, bricks were being used from the 2nd millennium BCE at a site near Xian, the carpenters manual Yingzao Fashi, published in 1103 at the time of the Song dynasty described the brick making process and glazing techniques then in use. He also had to know when to quench the kiln with water so as to produce the surface glaze, Early civilisations around the Mediterranean adopted the use of fired bricks, including the Ancient Greeks and Romans. The Roman legions operated mobile kilns, and built large brick structures throughout the Roman Empire, during the Early Middle Ages the use of bricks in construction became popular in Northern Europe, after being introduced there from Northern-Western Italy. An independent style of architecture, known as brick Gothic flourished in places that lacked indigenous sources of rocks. Examples of this style can be found in modern-day Denmark, Germany, Poland. A clear distinction between the two styles developed at the transition to Baroque architecture. In Lübeck, for example, Brick Renaissance is clearly recognisable in buildings equipped with terracotta reliefs by the artist Statius von Düren, 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 and 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 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. 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, the Bradley & Craven Ltd ‘Stiff-Plastic Brickmaking Machine’ was patented in 1853, apparently predating Clayton
15.
Calcium hydroxide
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Calcium hydroxide, traditionally called slaked lime, is an inorganic compound with the chemical formula Ca2. It is a crystal or white powder and is obtained when calcium oxide is mixed. It has many names including hydrated lime, caustic lime, builders lime, slack lime, cal, Calcium hydroxide is used in many applications, including food preparation. Limewater is the name for a saturated solution of calcium hydroxide. Calcium hydroxide is insoluble in water, with a solubility product Ksp of 5.5 × 10−6.4. Calcium hydroxide solutions can cause chemical burns, at high pH value, its solubility drastically decreases. This behavior is relevant to cement pastes, Ca2 → CaO + H2O Calcium hydroxide adopts a polymeric structure, as do all metal hydroxides. The structure is identical to that of Mg2, i. e. the cadmium iodide motif, strong hydrogen bonds exist between the layers. Calcium hydroxide is produced commercially by treating lime with water, CaO + H2O → Ca2 In the laboratory it can be prepared by mixing solutions of calcium chloride. The mineral form, portlandite, is rare but can be found in some volcanic, plutonic. It has also known to arise in burning coal dumps. CaOH has been detected in the atmosphere of S-type stars, one significant application of calcium hydroxide is as a flocculant, in water and sewage treatment. It forms a fluffy charged solid that aids in the removal of particles from water. This application is enabled by the low cost and low toxicity of calcium hydroxide and this conversion is part of the causticizing step in the Kraft process for making pulp. In Spanish, calcium hydroxide is called cal, corn cooked with cal becomes hominy, which significantly increases the bioavailability of niacin, and it is also considered tastier and easier to digest. In chewing coca leaves, calcium hydroxide is usually chewed alongside to keep the alkaloid stimulants chemically available for absorption by the body, similarly, Native Americans traditionally chewed tobacco leaves with calcium hydroxide derived from burnt mollusk shells to enhance the effects. It has also used by some indigenous American tribes as an ingredient in yopo. Calcium hydroxide is added to a bundle of areca nut
16.
Carbonation
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Carbonation can refer to two chemical processes involving carbon dioxide, The dissolution in a liquid, also known as fizz or effervescence. The process usually involves carbon dioxide under high pressure, when the pressure is reduced, the carbon dioxide is released from the solution as small bubbles, which causes the solution to become effervescent, or fizzy. A common example is the dissolving of carbon dioxide in water, carbon dioxide is weakly soluble in water, therefore it separates into a gas when the pressure is released. Carbonation also describes the incorporation of carbon dioxide into chemical compounds and this occurs in the following cases, In biochemistry Our carbon-based life originates from a carbonation reaction that is most often catalysed by the enzyme RuBisCO. So important is this process that a significant fraction of leaf mass consists of this carbonating enzyme. In reinforced concrete construction Also known as neutralisation, it is a reaction between carbon dioxide in the air and calcium hydroxide and hydrated calcium silicate in the concrete. Carbonation and Acidity Dissolution of Marble in Hydrochloric Acid Demonstration Robert OLeary, ATR Infrared Spectroscopy method for measuring CO2 concentration in Beer. Describes in detail the theory and practice of measuring dissolved CO2 content in soft drinks and beer
17.
Calcium carbonate
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Calcium carbonate is a chemical compound with the formula CaCO3. It is a substance found in rocks as the minerals calcite and aragonite and is the main component of pearls and the shells of marine organisms, snails. Calcium carbonate is the ingredient in agricultural lime and is created when calcium ions in hard water react with carbonate ions to create limescale. It is medicinally used as a supplement or as an antacid. Calcium carbonate shares the properties of other carbonates. CaCO3 + CO2 + H2O → Ca2 This reaction is important in the erosion of rock, forming caverns. An unusual form of calcium carbonate is the hexahydrate, ikaite, ikaite is stable only below 6 °C. The vast majority of calcium used in industry is extracted by mining or quarrying. Pure calcium carbonate, can be produced from a quarried source. Alternatively, calcium carbonate is prepared from calcium oxide, other forms can be prepared, the denser, orthorhombic λ-CaCO3 and μ-CaCO3, occurring as the mineral vaterite. The aragonite form can be prepared by precipitation at temperatures above 85 °C, calcite contains calcium atoms coordinated by 6 oxygen atoms, in aragonite they are coordinated by 9 oxygen atoms. The vaterite structure is not fully understood, magnesium carbonate MgCO3 has the calcite structure, whereas strontium and barium carbonate adopt the aragonite structure, reflecting their larger ionic radii. Calcite, aragonite and vaterite are pure calcium carbonate minerals, industrially important source rocks which are predominantly calcium carbonate include limestone, chalk, marble and travertine. Eggshells, snail shells and most seashells are predominantly calcium carbonate, oyster shells have enjoyed recent recognition as a source of dietary calcium, but are also a practical industrial source. While not practical as a source, dark green vegetables such as broccoli. Beyond Earth, strong evidence suggests the presence of Calcium carbonate on Mars, signs of Calcium Carbonate have been detected at more than one location. This provides some evidence for the past presence of liquid water, Carbonate is found frequently in geologic settings and constitute an enormous carbon reservoir. Calcium carbonate occurs as aragonite, calcite and dolomite, the carbonate minerals form the rock types, limestone, chalk, marble, travertine, tufa, and others
18.
Calcination
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Authorities differ on the meaning of calcination. The IUPAC defines it as heating to temperatures in air or oxygen. A calciner is a cylinder that rotates inside a heated furnace. The product of calcination is usually referred to in general as calcine, calcination is carried out in furnaces or reactors of various designs including shaft furnaces, rotary kilns, multiple hearth furnaces, and fluidized bed reactors. Calcination reactions usually take place at or above the decomposition temperature or the transition temperature. This temperature is defined as the temperature at which the standard Gibbs free energy for a particular calcination reaction is equal to zero. For example, in limestone calcination, a process, the chemical reaction is CaCO3 → CaO + CO2 The standard Gibbs free energy of reaction is approximated as ΔG°r =177,100 −158 T. The standard free energy of reaction is 0 in this case when the temperature, T, is equal to 1121 K, see also calcination equilibrium of calcium carbonate In some cases, calcination of a metal results in oxidation of the metal. Jean Rey noted that lead and tin when calcinated gained weight, in alchemy, calcination was believed to be one of the 12 vital processes required for the transformation of a substance. Alchemists distinguished two kinds of calcination, actual and potential, actual calcination is that brought about by actual fire, from wood, coals, or other fuel, raised to a certain temperature
19.
Atmospheric pressure
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Atmospheric pressure, sometimes also called barometric pressure, is the pressure exerted by the weight of air in the atmosphere of Earth. In most circumstances atmospheric pressure is approximated by the hydrostatic pressure caused by the weight of air above the measurement point. As elevation increases, there is less overlying atmospheric mass, so that atmospheric pressure decreases with increasing elevation. On average, a column of air one square centimetre in cross-section, measured from sea level to the top of the atmosphere, has a mass of about 1.03 kilograms and that force is a pressure of 10.1 N/cm2 or 101 kN/m2. A column 1 square inch in cross-section would have a weight of about 14.7 lb or about 65.4 N and it is modified by the planetary rotation and local effects such as wind velocity, density variations due to temperature and variations in composition. The standard atmosphere is a unit of pressure defined as 101325 Pa, the mean sea level pressure is the average atmospheric pressure at sea level. This is the pressure normally given in weather reports on radio, television. When barometers in the home are set to match the weather reports, they measure pressure adjusted to sea level. The altimeter setting in aviation, is an atmospheric pressure adjustment, average sea-level pressure is 1013.25 mbar. In aviation weather reports, QNH is transmitted around the world in millibars or hectopascals, except in the United States, Canada, however, in Canadas public weather reports, sea level pressure is instead reported in kilopascals. The highest sea-level pressure on Earth occurs in Siberia, where the Siberian High often attains a sea-level pressure above 1050 mbar, the lowest measurable sea-level pressure is found at the centers of tropical cyclones and tornadoes, with a record low of 870 mbar. Pressure varies smoothly from the Earths surface to the top of the mesosphere, although the pressure changes with the weather, NASA has averaged the conditions for all parts of the earth year-round. As altitude increases, atmospheric pressure decreases, one can calculate the atmospheric pressure at a given altitude. Temperature and humidity affect the atmospheric pressure, and it is necessary to know these to compute an accurate figure. The graph at right was developed for a temperature of 15 °C, at low altitudes above the sea level, the pressure decreases by about 1.2 kPa for every 100 meters. See pressure system for the effects of air pressure variations on weather, Atmospheric pressure shows a diurnal or semidiurnal cycle caused by global atmospheric tides. This effect is strongest in tropical zones, with an amplitude of a few millibars and these variations have two superimposed cycles, a circadian cycle and semi-circadian cycle. The highest adjusted-to-sea level barometric pressure recorded on Earth was 1085.7 hPa measured in Tosontsengel
20.
Belite
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Belite is an industrial mineral important in Portland cement manufacture. Its main constituent is dicalcium silicate, Ca2SiO4, sometimes formulated as 2 CaO · SiO2, the name was given by Törneborn in 1897 to a crystal identified in microscopic investigation of Portland cement. Belite is a name in use in the cement industry. It occurs naturally as the mineral larnite, the name being derived from Larne, Northern Ireland, the belite found in Portland cement differs in composition from pure dicalcium silicate. It is a solution and contains minor amounts of other oxides besides CaO. A typical composition, Based on this, the formula can be expressed as Ca1. 94Mg0. 02Na0. 01K0. 03Fe0. 02Al0. 07Si0. 90P0. 01O3.93. In practice, the composition varies with the composition of the clinker. Substitution of calcium ions or orthosilicate ions requires that electric charges be kept in balance, for instance, a limited number of orthosilicate ions can be replaced with sulfate ions, provided that for each sulfate ion, two aluminate ions are also substituted. Dicalcium silicate is stable, and is prepared from reactive CaO. The low temperature form is γ-belite, or lime olivine and this form does not hydrate, and is avoided in cement manufacture. As the temperature rises, it passes through several polymorphic states, the other silicate, alite contributes early strength, due to its higher reactivity. The hydrate phase, is referred to as the C-S-H phase and it grows as a mass of interlocking needles that provide the strength of the hydrated cement system. Relatively high belite reactivity is desirable in Portland cement manufacture, and this is achieved by rapid cooling, forming crystals that are small, distorted and highly defective. Defects provide sites for initial water attack, failure to cool the clinker rapidly leads to inversion of belite to the γ-form. This is observed macroscopically as dusting, the clinker nodules fall to a fine dust, the minerals in Portland cement clinker may be observed and quantified by petrographic microscopy. Clinker nodules are cut and ground to a flat, polished surface, the exposed minerals are made visible and identifiable by etching the surface. The surface can then be observed in reflected light by optical microscopy, in the example, a clinker nodule has been polished and etched with hydrogen fluoride vapour. The alite shows as brown, the belite as blue, electron microscopy can also be used, in which case the minerals may be identified by microprobe analysis
21.
Alite
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Alite is a name for tricalcium silicate, Ca3SiO5, sometimes formulated as 3CaO·SiO2. It is the major, and characteristic, mineral phase in Portland cement, the name was given by Törneborn in 1897 to a crystal identified in microscopic investigation of Portland cement. Alite is a name in use in the cement industry. The alite found in Portland cement differs in composition from simple tricalcium silicate and it is a solid solution and contains minor amounts of other oxides besides CaO and SiO2. A typical composition is, Based on this, the formula can be expressed as Ca2. 90Mg0. 06Na0. 01Fe0. 03Al0. 04Si0. 95P0. 01O5, in practice, the composition varies with the bulk composition of the clinker, subject to certain limits. Substitution of calcium ions or orthosilicate ions requires that electric charges be kept in balance, for instance, a limited number of orthosilicate ions can be replaced with sulfate ions, provided that for each sulfate ion, two aluminate ions are also substituted. Tricalcium silicate is thermodynamically unstable below 1250 °C, but can be preserved in a state at room temperature by fast cooling, on slow cooling it tends to revert to belite. As the temperature changes, it passes through several polymorphic states, alite is the mineral in Portland cement responsible for setting and development of early strength. The other silicate, belite contributes late strength, due to its lower reactivity, alite is more reactive because of its higher Ca content, and the presence of an oxide ion in the lattice. During clinker grinding, first step of partial dissolution of C3S involves hydration of superficial oxide ions and it grows as a mass of interlocking needles that provide the strength of the hydrated cement system. Defects provide sites for initial water attack, indeed, in the area of Tournai, the Tournaisian limestones are particularly rich in amorphous silica and exploited as building stone and for making lime mortar since very ancient ages. It is unknown if the builders of this area were aware of the hydraulic properties of their lime mortar or intentionally developed its use after their fortuitous finding
22.
Brownmillerite
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Brownmillerite is a rare oxide mineral with chemical formula Ca22O5. It is named for Lorrin Thomas Brownmiller, chief chemist of the Alpha Portland Cement Company, Easton, the chemical compound was first recognized in 1932 and named for the chemist who identified it. The naturally occurring form of the compound was first recognized in 1964 for occurrences in the Bellerberg volcano, Ettringen, Mayen-Koblenz. At the type locality the mineral occurs within limestone blocks that are contained in a volcanic flow, the limestone blocks had undergone thermal metamorphism. The mineral also occurs in the thermally altered strata of the Hatrurim Formation of Israel, in an Austrian occurrence near Kloch, melilite, mayenite, wollastonite, kalsilite and corundum are found. Within the Hatrurim area spurrite, larnite and mayenite are associated, the mineral is similar to the calcium aluminoferrite phases which are commonly found as components of Portland cement
23.
Bitumen
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Asphalt, also known as bitumen is a sticky, black and highly viscous liquid or semi-solid form of petroleum. It may be found in deposits or may be a refined product. Until the 20th century, the term asphaltum was also used, the word is derived from the Ancient Greek ἄσφαλτος ásphaltos. The primary use of asphalt/bitumen is in construction, where it is used as the glue or binder mixed with aggregate particles to create asphalt concrete. Its other main uses are for bituminous waterproofing products, including production of roofing felt, the terms asphalt and bitumen are often used interchangeably to mean both natural and manufactured forms of the substance. In American English, asphalt is the carefully refined residue from the process of selected crude oils. Outside the United States, the product is often called bitumen, geologists often prefer the term bitumen. Common usage often refers to forms of asphalt/bitumen as tar. Naturally occurring asphalt/bitumen is sometimes specified by the crude bitumen. Its viscosity is similar to that of cold molasses while the material obtained from the distillation of crude oil boiling at 525 °C is sometimes referred to as refined bitumen. The Canadian province of Alberta has most of the reserves of natural bitumen, covering 142,000 square kilometres. Additionally, most natural bitumens contain organosulfur compounds, resulting in a sulfur content of up to 4%. Nickel and vanadium are found in the <10 ppm level, as is typical of some petroleum, the substance is soluble in carbon disulfide. It is commonly modelled as a colloid, with asphaltenes as the dispersed phase, and it is almost impossible to separate and identify all the different molecules of asphalt, because the number of molecules with different chemical structure is extremely large. Asphalt/bitumen can sometimes be confused with tar, which is a visually similar black. During the early and mid-20th century when town gas was produced, coal tar was a readily available byproduct, the addition of tar to macadam roads led to the word tarmac, which is now used in common parlance to refer to road-making materials. However, since the 1970s, when natural gas succeeded town gas, other examples of this confusion include the La Brea Tar Pits and the Canadian oil sands, both of which actually contain natural bitumen rather than tar. Pitch is another term used at times to refer to asphalt/bitumen
24.
Sand
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Sand is a naturally occurring granular material composed of finely divided rock and mineral particles. It is defined by size, being finer than gravel and coarser than silt, Sand can also refer to a textural class of soil or soil type, i. e. a soil containing more than 85% sand-sized particles by mass. The second most common type of sand is calcium carbonate, for example aragonite, for example, it is the primary form of sand apparent in areas where reefs have dominated the ecosystem for millions of years like the Caribbean. Sand is a non renewable resource over human timescales, and sand suitable for making concrete is in high demand, in terms of particle size as used by geologists, sand particles range in diameter from 0.0625 mm to 2 mm. An individual particle in this size is termed a sand grain. Sand grains are between gravel and silt, a 1953 engineering standard published by the American Association of State Highway and Transportation Officials set the minimum sand size at 0.074 mm. A1938 specification of the United States Department of Agriculture was 0.05 mm. Sand feels gritty when rubbed between the fingers. ISO14688 grades sands as fine, medium and coarse with ranges 0.063 mm to 0.2 mm to 0.63 mm to 2.0 mm. In the United States, sand is commonly divided into five sub-categories based on size, very fine sand, fine sand, medium sand, coarse sand, and very coarse sand. These sizes are based on the Krumbein phi scale, where size in Φ = -log2D, on this scale, for sand the value of Φ varies from −1 to +4, with the divisions between sub-categories at whole numbers. The composition of sand is highly variable, depending on the local rock sources. The gypsum sand dunes of the White Sands National Monument in New Mexico are famous for their bright, arkose is a sand or sandstone with considerable feldspar content, derived from weathering and erosion of a granitic rock outcrop. Some sands contain magnetite, chlorite, glauconite or gypsum, Sands rich in magnetite are dark to black in color, as are sands derived from volcanic basalts and obsidian. Chlorite-glauconite bearing sands are typically green in color, as are sands derived from basaltic with a high olivine content, many sands, especially those found extensively in Southern Europe, have iron impurities within the quartz crystals of the sand, giving a deep yellow color. Sand deposits in some areas contain garnets and other resistant minerals, the study of individual grains can reveal much historical information as to the origin and kind of transport of the grain. Quartz sand that is weathered from granite or gneiss quartz crystals will be angular. It is called grus in geology or sharp sand in the trade where it is preferred for concrete. Sand that is transported long distances by water or wind will be rounded, people who collect sand as a hobby are known as arenophiles
25.
Gypsum
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Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. It is widely mined and is used as a fertilizer, and as the constituent in many forms of plaster, blackboard chalk. Mohs scale of hardness, based on scratch Hardness comparison. It forms as a mineral and as a hydration product of anhydrite. The word gypsum is derived from the Greek word γύψος, plaster, because the quarries of the Montmartre district of Paris have long furnished burnt gypsum used for various purposes, this dehydrated gypsum became known as plaster of Paris. Upon addition of water, after a few tens of minutes plaster of Paris becomes regular gypsum again, causing the material to harden or set in ways that are useful for casting, Gypsum was known in Old English as spærstān, spear stone, referring to its crystalline projections. Gypsum may act as a source of sulfur for plant growth, which was discovered by J. M. Mayer, american farmers were so anxious to acquire it that a lively smuggling trade with Nova Scotia evolved, resulting in the so-called Plaster War of 1820. In the 19th century, it was known as lime sulfate or sulfate of lime. Gypsum is moderately water-soluble and, in contrast to most other salts, it exhibits retrograde solubility, when gypsum is heated in air it loses water and converts first to calcium sulfate hemihydrate, and, if heated further, to anhydrous calcium sulfate. As for anhydrite, its solubility in saline solutions and in brines is also dependent on NaCl concentration. Gypsum crystals are found to contain water and hydrogen bonding. Gypsum occurs in nature as flattened and often twinned crystals, and transparent, selenite contains no significant selenium, rather, both substances were named for the ancient Greek word for the Moon. Selenite may also occur in a silky, fibrous form, in case it is commonly called satin spar. Finally, it may also be granular or quite compact, in hand-sized samples, it can be anywhere from transparent to opaque. A very fine-grained white or lightly tinted variety of gypsum, called alabaster, is prized for ornamental work of various sorts, in arid areas, gypsum can occur in a flower-like form, typically opaque, with embedded sand grains called desert rose. It also forms some of the largest crystals found in nature, up to 12 m long, Gypsum is a common mineral, with thick and extensive evaporite beds in association with sedimentary rocks. Deposits are known to occur in strata from as far back as the Archaean eon, Gypsum is deposited from lake and sea water, as well as in hot springs, from volcanic vapors, and sulfate solutions in veins. Hydrothermal anhydrite in veins is commonly hydrated to gypsum by groundwater in near-surface exposures and it is often associated with the minerals halite and sulfur
26.
Minoan civilization
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The Minoan civilization was an Aegean Bronze Age civilization on the island of Crete and other Aegean islands which flourished from about 2600 to 1100 BC. It preceded the Mycenaean civilization of Ancient Greece, the civilization was rediscovered at the beginning of the 20th century through the work of British archaeologist Arthur Evans. It has been described as the earliest of its kind in Europe, the term Minoan, which refers to the mythical King Minos, originally described the pottery of the period. Minos was associated in Greek mythology with the labyrinth and the Minotaur, according to Homer, Crete once had 90 cities. The Minoan period saw trade between Crete and Aegean and Mediterranean settlements, particularly the Near East, traders and artists, the Minoan cultural influence reached beyond Crete to the Cyclades, Egypts Old Kingdom, copper-bearing Cyprus, Canaan and the Levantine coast, and Anatolia. Some of its best art is preserved in the city of Akrotiri on the island of Santorini, although the Minoan language and writing systems remain undecipherable and are subjects of academic dispute, they apparently conveyed a language entirely different from the later Greek. The reason for the end of the Minoan period is unclear, theories include Mycenaean invasions from mainland Greece, the term Minoan refers to the mythical King Minos of Knossos. Its origin is debated, but it is attributed to archeologist Arthur Evans. Minos was associated in Greek mythology with the labyrinth, which Evans identified with the site at Knossos. However, Karl Hoeck had already used the title Das Minoische Kreta in 1825 for volume two of his Kreta, this appears to be the first known use of the word Minoan to mean ancient Cretan, Evans said that applied it, not invented it. Hoeck, with no idea that the archaeological Crete had existed, had in mind the Crete of mythology, although Evans 1931 claim that the term was unminted before he used it was called a brazen suggestion by Karadimas and Momigliano, he coined its archaeological meaning. Instead of dating the Minoan period, archaeologists use two systems of relative chronology, the first, created by Evans and modified by later archaeologists, is based on pottery styles and imported Egyptian artifacts. Evans system divides the Minoan period into three eras, early, middle and late. These eras are subdivided—for example, Early Minoan I, II and III, another dating system, proposed by Greek archaeologist Nicolas Platon, is based on the development of architectural complexes known as palaces at Knossos, Phaistos, Malia and Kato Zakros. Platon divides the Minoan period into pre-, proto-, neo-, the relationship between the systems in the table includes approximate calendar dates from Warren and Hankey. The Thera eruption occurred during a phase of the LM IA period. Efforts to establish the volcanic eruptions date have been controversial, the eruption is identified as a natural event catastrophic for the culture, leading to its rapid collapse. Although stone-tool evidence exists that hominins may have reached Crete as early as 130,000 years ago, evidence for the first anatomically-modern human presence dates to 10, the oldest evidence of modern human habitation on Crete are pre-ceramic Neolithic farming-community remains which date to about 7000 BC
27.
Pozzolan
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The quantification of the capacity of a pozzolan to react with calcium hydroxide and water is given by measuring its pozzolanic activity. Pozzolana are naturally occurring pozzolans of volcanic origin, mixtures of calcined lime and finely ground, reactive aluminosilicate materials were pioneered and developed as inorganic binders in the Ancient world. Evidence of the use of volcanic materials such as volcanic ashes or tuffs by the ancient Greeks dates back to at least 500–400 BC, as uncovered at the ancient city of Kameiros. In subsequent centuries the practice spread to the mainland and was eventually adopted, the Romans used volcanic pumices and tuffs found in neighbouring territories, the most famous ones found in Pozzuoli, hence the name pozzolan, and in Segni. Preference was given to natural sources such as German trass. Much of the skill and knowledge regarding the use of pozzolans was lost at the decline of the Roman empire. The rediscovery of Roman architectural practices as described by Vitruvius in De architectura, particularly the strength, durability and hydraulic capability of hardening underwater made them popular construction materials during the 16th–18th century. Over the course of the 20th century the use of pozzolans as additions to Portland cement concrete mixtures has become common practice, the general definition of a pozzolan embraces a large number of materials which vary widely in terms of origin, composition and properties. Both natural and artificial materials show pozzolanic activity and are used as supplementary cementitious materials and their use has been firmly established and regulated in many countries. However, the supply of high-quality pozzolanic by-products is limited and many sources are already fully exploited. Natural pozzolanas are abundant in locations and are extensively used as an addition to Portland cement in countries such as Italy, Germany, Greece. Volcanic ashes and pumices largely composed of glass are commonly used. Deposits of sedimentary origin are less common, diatomaceous earths, formed by the accumulation of siliceous diatom microskeletons, are a prominent source material here. The benefits of pozzolan use in cement and concrete are threefold, first is the economic gain obtained by replacing a substantial part of the Portland cement by cheaper, pollution free, natural pozzolans or industrial by-products. Second is the lowering of the blended cement environmental cost associated with the gases emitted during Portland cement production. A third advantage is the durability of the end product. Blending of pozzolans with Portland cement is of limited interference in the production process. A reduction of 40 percent of Portland cement in the mix is usually feasible when replaced with a combination of pozzolanic materials
28.
Ancient Macedonians
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The Macedonians were an ancient tribe that lived on the alluvial plain around the rivers Haliacmon and lower Axios in the northeastern part of mainland Greece. They spoke a dialect of Greek, although the lingua franca of the region was at first Attic. Aside from the monarchy, the core of Macedonian society was its nobility, similar to the aristocracy of neighboring Thessaly, their wealth was largely built on herding horses and cattle. Although composed of clans, the kingdom of Macedonia, established around the 8th century BC, is mostly associated with the Argead dynasty. The dynasty was founded by Perdiccas I, descendant of the legendary Temenus of Argos, while the region of Macedon perhaps derived its name from Makedon. Traditionally ruled by independent families, the Macedonians seem to have accepted Argead rule by the time of Alexander I, under Philip II, the Macedonians are credited with numerous military innovations, which enlarged their territory and increased their control over other areas extending into Thrace. There is also debate over the classification of the native Macedonian language as a dialect of the Greek language or as its own subdivision of the Hellenic languages. With the scant amount of evidence, the extent to which the native Macedonian tongue may have been influenced by the Phrygian, Thracian. The ancient Macedonians participated in the production and fostering of Classical, in terms of visual arts, they produced frescoes, mosaics, sculptures, and decorative metalwork. The performing arts of music and Greek theatrical dramas were highly appreciated, the kingdom also attracted the presence of renowned philosophers, such as Aristotle, while native Macedonians contributed to the field of ancient Greek literature, especially Greek historiography. Their sport and leisure activities included hunting, foot races, and chariot races, the expansion of the Macedonian kingdom has been described as a three-stage process. Macedonia then led a military force against their primary objective—the conquest of Persia—which they achieved with remarkable ease. With Alexanders conquest of the Achaemenid Empire, Macedonians colonized territories as far east as Central Asia, the Macedonians continued to rule much of Hellenistic Greece, forming alliances with Greek leagues such as the Cretan League and Epirote League. In the aftermath of the Third Macedonian War, the Romans abolished the Macedonian monarchy under Perseus of Macedon, a brief revival of the monarchy by the pretender Andriscus led to the Fourth Macedonian War, after which Rome established the Roman province of Macedonia and subjugated the Macedonians. In Greek mythology, Makedon is the hero of Macedonia and is mentioned in Hesiods Catalogue of Women. The first historical attestation of the Macedonians occurs in the works of Herodotus during the mid-5th century BC, the Macedonians are absent in Homers Catalogue of Ships and the term Macedonia itself appears late. The Iliad states that upon leaving Mount Olympus, Hera journeyed via Pieria and Emathia before reaching Athos and this is re-iterated by Strabo in his Geography. Nevertheless, archaeological evidence indicates that Mycenaean contact with or penetration into the Macedonian interior possibly started from the early 14th century BC, in their new Pierian home north of Olympus, the Macedonian tribes mingled with the proto-Dorians
29.
Roman engineering
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Romans are famous for their advanced engineering accomplishments, although some of their own inventions were improvements on older ideas, concepts and inventions. Technology for bringing running water into cities was developed in the east, the architecture used in Rome was strongly influenced by Greek and Etruscan sources. Roads were common at time, but the Romans improved their design. Moreover, their contributions were described in detail by authors such as Vitruvius, Frontinus and Pliny the Elder, so there is a printed record of their many inventions. 1,000 cubic metres of water were brought into Rome by 14 different aqueducts each day, per capita water usage in ancient Rome matched that of modern-day cities like New York City or modern Rome. Most water was for use, such as baths and sewers. De aquaeductu is the two volume treatise on 1st century aqueducts of Rome, written by Frontinus. The aqueducts could stretch from 10–100 km long, and typically descended from an elevation of 300 m above sea level at the source, Roman engineers used inverted siphons to move water across a valley if they judged it impractical to build a raised aqueduct. The Roman legions were largely responsible for building the aqueducts, maintenance was often done by slaves. The Romans were among the first civilizations to harness the power of water and they built some of the first watermills outside of Greece for grinding flour and spread the technology for constructing watermills throughout the Mediterranean region. It is known that they were capable of building and operating mining equipment such as crushing mills. Large diameter vertical wheels of Roman vintage, for raising water, have been excavated from the Rio Tinto mines in Southwestern Spain, Roman bridges were among the first large and lasting bridges ever built. They were built with stone, employing the arch as basic structure, built in 142 BC, the Pons Aemilius, later named Ponte Rotto is the oldest Roman stone bridge in Rome, Italy. They were normally at least 18 meters above the body of water, an example of temporary military bridge construction are the two Caesars Rhine bridges. The Romans built many dams for water collection, such as the Subiaco dams, one of the Subiaco dams was reputedly the highest ever found or inferred. They built 72 dams in Spain, such as those at Mérida, at one site, Montefurado in Galicia, they appear to have built a dam across the river Sil to expose alluvial gold deposits in the bed of the river. The site is near the spectacular Roman gold mine of Las Medulas, tanks for holding water are also common along aqueduct systems, and numerous examples are known from just one site, the gold mines at Dolaucothi in west Wales. Masonry dams were common in North Africa for providing a water supply from the wadis behind many settlements
30.
Baiae
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Baiae was a mineral springs and coastal resort on the northwest shore of the Gulf of Naples in ancient Italy. It was fashionable for centuries during antiquity, particularly towards the end of the Roman Republic, when it was reckoned as superior to Pompeii, Herculaneum and it was notorious for its hedonistic offerings and the attendant rumors of corruption and scandal. It later formed part of Port Julius, the base of the fleet of the Imperial Roman Navy. It was deserted and its ruins largely submerged by volcanic activity by the time of the Renaissance. What is left of Baia is now a frazione of the comune of Bacoli in the Campania region of Italy, Baiae was said to have been named after Baius, the helmsman of Odysseuss ship in Homers Odyssey, who was supposedly buried nearby. The adjacent Baian Gulf was named after the town and it now forms the western part of the Gulf of Pozzuoli. The settlement was mentioned in 178 BC under the name Aquae Cumanae. Baiae was built on the Cumaean Peninsula in the Phlegraean Fields and it perhaps originally developed as the port for Cumae. The bathhouses of Baiae were filled with mineral water directed to its pools from underground sulfur springs. Roman engineers were able to construct a complex system of chambers that channeled underground heat into facilities that acted as saunas. In addition to their function, the baths were used in Roman medicine to treat various illnesses. Baiae was particularly fashionable towards the end of the Roman Republic, marius, Lucullus, and Pompey all frequented it. Julius Caesar had a villa there, and much of the town became imperial property under Augustus, with its large swimming pools and domed casino, it continued to be a getaway for the elite. Nero had a villa constructed in the middle of the 1st century. It was also a spot of the emperor Septimius Severus. Caligula ordered a 3-mile-long pontoon bridge to be built from impounded ships of the area, fastened together and weighted with sand, clad in a gold cloak, he then crossed it upon a horse. Cassius Dios Roman History also includes the event, with the detail that the emperor ordered resting places and lodging rooms with potable water erected at intervals along the bridge. As late as the 18th century, scattered fragments were still being shown to tourists as the Bridge of Caligula. ”Baiae was notorious for the lifestyle of its residents and guests
31.
Santorini
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Santorini, classically Thera, and officially Thira, is an island in the southern Aegean Sea, about 200 km southeast of Greeces mainland. It is the largest island of a small, circular archipelago which bears the name and is the remnant of a volcanic caldera. It forms the southernmost member of the Cyclades group of islands, with an area of approximately 73 km2, the municipality of Santorini includes the inhabited islands of Santorini and Therasia and the uninhabited islands of Nea Kameni, Palaia Kameni, Aspronisi, and Christiana. The total land area is 90.623 km2, Santorini is part of the Thira regional unit. Santorini is essentially what remains after a volcanic eruption that destroyed the earliest settlements on a formerly single island. A giant central, rectangular lagoon, which measures about 12 by 7 km, is surrounded by 300 m high, the main island slopes downward to the Aegean Sea. On the fourth side, the lagoon is separated from the sea by another smaller island called Therasia. The islands principal port is Athinios, the capital, Fira, clings to the top of the cliff looking down on the lagoon. The volcanic rocks present from the prior eruptions feature olivine, and have a presence of hornblende. It is the most active volcanic centre in the South Aegean Volcanic Arc, the volcanic arc is approximately 500 km long and 20 to 40 km wide. The island is the site of one of the largest volcanic eruptions in recorded history, the Minoan eruption, another popular theory holds that the Thera eruption is the source of the legend of Atlantis. Before then, it was known as Kallístē, Strongýlē, or Thēra, the name Thera was revived in the nineteenth century as the official name of the island and its main city, but the colloquial name Santorini is still in popular use. During the Ottoman Empires domination of the Aegean Sea, the Turkish exonym for the island was Santurin or Santoron, Oia is now called a Κοινότητα, within the municipality of Thera, and it consists of the local subdivisions of Therasia and Oia. The two main sources of wealth in Santorini are agriculture and tourism, in recent years, Santorini has been voted one of the worlds most beautiful islands. Santorini remains the home of a small, but flourishing wine industry, white varieties also include Athiri and Aidani, whereas red varieties include mavrotragano and mandilaria. The Cyclades are part of a complex that is known as the Cycladic Massif. The complex formed during the Miocene and was folded and metamorphosed during the Alpine orogeny around 60 million years ago, Thera is built upon a small, non-volcanic basement that represents the former non-volcanic island, which was approximately 9 by 6 km. The basement rock is composed of metamorphosed limestone and schist
32.
Pozzuoli
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Pozzuoli is a city and comune of the Metropolitan City of Naples, in the Italian region of Campania. It is the city of the Phlegrean Peninsula. Pozzuoli began as the Greek colony of Dicaearchia, the Roman colony was established in 194 BC, and took the name Puteoli which it has his roots from puteus, meaning well and osco fistulus. An alternative etymology of Puteoli from the Latin puteo, referring to the smell in the area. This is because Pozzuoli lies in the center of the Campi Flegrei, Puteoli was the great emporium for the Alexandrian grain ships, and other ships from all over the Roman world. It also was the hub for goods exported from Campania, including blown glass, mosaics, wrought iron. The Roman naval base at nearby Misenum housed the largest naval fleet in the ancient world and it was also the site of the Roman Dictator Sullas country villa and the place where he died in 78 BC. The local volcanic sand, pozzolana formed the basis for the first effective concrete, instead of just evaporating slowly off, the water would turn this sand/lime mix into a mortar strong enough to bind lumps of aggregate into a load-bearing unit. This made possible the cupola of the Pantheon, which is still the worlds largest unreinforced concrete dome, the apostle Paul landed here on his way to Rome, from which it was 170 miles distant. Here he stayed for seven days and then began with his companions his journey by the Appian Way to Rome, Puteoli is considered the best candidate for the unnamed city where the 1st century Roman novel Satyricon takes place. Saint Proculus was martyred here with his companions in the fourth century, the seven eagle heads on the coat-of-arms for the town of Pozzuoli are said to represent seven of these martyrs. November 16 was the official feast day for Saint Proculus, st. Proculus was affectionately nicknamed u pisciasotto because November 16 was often a day of rain. The townspeople also celebrated his feast day on the second Sunday in May, charles Lyell visited Pozzuoli in 1828 and studied the Macellum columns. The events raised the sea bottom by almost 2 m, the towns attractions include, The Macellum of Pozzuoli, also known as the Temple of Serapis or serapeum, is considered the citys symbol. The temple was actually a marketplace and its name derives from the misinterpretation of its function after a statue of the god Serapis was found in 1750 at this location. Flavian Amphitheater, the third largest Italian amphitheater after the Colosseum, Solfatara Forum Minor Amphitheater, very near to the Flavian one, its remains were absorbed by other buildings, but some arches can be seen by Via Solfatara and Via Vigna. Villa Avellino, one of the few urban parks of Pozzuoli and it also shows several Roman ruins and water tanks. There is also a still working Roman face water fountain, rione Terra, the first settlement of Puteoli, originally Dicearkia in Greek
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Dome
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A dome is an architectural element that resembles the hollow upper half of a sphere. The precise definition has been a matter of controversy, there are also a wide variety of forms and specialized terms to describe them. A dome can rest upon a rotunda or drum, and can be supported by columns or piers that transition to the dome through squinches or pendentives, a lantern may cover an oculus and may itself have another dome. Domes have a long architectural lineage that extends back into prehistory and they have been constructed from mud, snow, stone, wood, brick, concrete, metal, glass, and plastic over the centuries. The symbolism associated with domes includes mortuary, celestial, and governmental traditions that have developed over time. Domes have been found from early Mesopotamia, which may explain the forms spread and they are found in Persian, Hellenistic, Roman, and Chinese architecture in the Ancient world, as well as among a number of contemporary indigenous building traditions. They were popular in Byzantine and medieval Islamic architecture, and there are examples from Western Europe in the Middle Ages. The Renaissance style spread from Italy in the Early modern period, advancements in mathematics, materials, and production techniques since that time resulted in new dome types. The domes of the world can be found over religious buildings, legislative chambers, sports stadiums. The English word dome ultimately derives from the Latin domus —which, up through the Renaissance, labeled a revered house, such as a Domus Dei, or House of God, the French word dosme came to acquire the meaning of a cupola vault, specifically, by 1660. A dome is a rounded vault made of either curved segments or a shell of revolution, sometimes called false domes, corbel domes achieve their shape by extending each horizontal layer of stones inward slightly farther than the lower one until they meet at the top. A false dome may also refer to a wooden dome, true domes are said to be those whose structure is in a state of compression, with constituent elements of wedge-shaped voussoirs, the joints of which align with a central point. The validity of this is unclear, as domes built underground with corbelled stone layers are also in compression from the surrounding earth, as with arches, the springing of a dome is the level from which the dome rises. The top of a dome is the crown, the inner side of a dome is called the intrados and the outer side is called the extrados. The haunch is the part of an arch that lies halfway between the base and the top. The word cupola is another word for dome, and is used for a small dome upon a roof or turret. Cupola has also used to describe the inner side of a dome. Drums, also called tholobates, are cylindrical or polygonal walls with or without windows that support a dome, a tambour or lantern is the equivalent structure over a domes oculus, supporting a cupola
34.
Pantheon, Rome
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The Pantheon is a former Roman temple, now a church, in Rome, Italy, on the site of an earlier temple commissioned by Marcus Agrippa during the reign of Augustus. The present building was completed by the emperor Hadrian and probably dedicated about 126 AD and he retained Agrippas original inscription, which has confused its date of construction as the original Pantheon burnt down so it is not certain when the present one was built. The building is circular with a portico of large granite Corinthian columns under a pediment, a rectangular vestibule links the porch to the rotunda, which is under a coffered concrete dome, with a central opening to the sky. Almost two thousand years after it was built, the Pantheons dome is still the worlds largest unreinforced concrete dome, the height to the oculus and the diameter of the interior circle are the same,43.3 metres. Mary and the Martyrs but informally known as Santa Maria Rotonda, the square in front of the Pantheon is called Piazza della Rotonda. The Pantheon is a property, ruled by Italys Ministry of Cultural Heritage and Activities and Tourism through the Polo Museale del Lazio. The Pantheons large circular domed cella, with a temple portico front, is unique in Roman architecture. Nevertheless, it became a standard exemplar when classical styles were revived, Pantheon is derived from the Ancient Greek Pantheion meaning of, relating to, or common to all the gods. His uncertainty strongly suggests that Pantheon was merely a nickname, not the name of the building. In fact, the concept of a dedicated to all the gods is questionable. The only definite pantheon recorded earlier than Agrippas was at Antioch in Syria and it seems highly significant that Dio does not quote the simplest explanation for the name—that the Pantheon was dedicated to all the gods. Godfrey and Hemsoll maintain that the word Pantheon need not denote a group of gods, or, indeed, even all the gods. Certainly the word pantheus or pantheos, could be applicable to individual deities…, bearing in mind also that the Greek word θεῖος need not mean of a god but could mean superhuman, or even excellent. It seems likely that the Pantheon and the Basilica of Neptune were Agrippas sacra privata and this less solemn designation would help explain how the building could have so easily lost its original name and purpose in such a relatively short period of time. However, archaeological excavations have shown that the Pantheon of Agrippa had been destroyed except for the façade. Lise Hetland argues that the present construction began in 114, under Trajan and her argument is particularly interesting in light of Heilmeyers argument that, based on stylistic evidence, Apollodorus of Damascus, Trajans architect, was the obvious architect. The form of Agrippas Pantheon is debated and this description was widely accepted until the late 20th century. The only passages referring to the decoration of the Agrippan Pantheon written by an eyewitness are in Plinys Natural History, from him we know that the capitals, too, of the pillars, which were placed by M
35.
Rome
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Rome is a special comune and the capital of Italy. Rome also serves as the capital of the Lazio region, with 2,873,598 residents in 1,285 km2, it is also the countrys largest and most populated comune and fourth-most populous city in the European Union by population within city limits. It is the center of the Metropolitan City of Rome, which has a population of 4.3 million residents, the city is located in the central-western portion of the Italian Peninsula, within Lazio, along the shores of the Tiber. Romes history spans more than 2,500 years, while Roman mythology dates the founding of Rome at only around 753 BC, the site has been inhabited for much longer, making it one of the oldest continuously occupied sites in Europe. The citys early population originated from a mix of Latins, Etruscans and it was first called The Eternal City by the Roman poet Tibullus in the 1st century BC, and the expression was also taken up by Ovid, Virgil, and Livy. Rome is also called the Caput Mundi, due to that, Rome became first one of the major centres of the Italian Renaissance, and then the birthplace of both the Baroque style and Neoclassicism. Famous artists, painters, sculptors and architects made Rome the centre of their activity, in 1871 Rome became the capital of the Kingdom of Italy, and in 1946 that of the Italian Republic. Rome has the status of a global city, Rome ranked in 2014 as the 14th-most-visited city in the world, 3rd most visited in the European Union, and the most popular tourist attraction in Italy. Its historic centre is listed by UNESCO as a World Heritage Site, monuments and museums such as the Vatican Museums and the Colosseum are among the worlds most visited tourist destinations with both locations receiving millions of tourists a year. Rome hosted the 1960 Summer Olympics and is the seat of United Nations Food, however, it is a possibility that the name Romulus was actually derived from Rome itself. As early as the 4th century, there have been alternate theories proposed on the origin of the name Roma. There is archaeological evidence of occupation of the Rome area from approximately 14,000 years ago. Evidence of stone tools, pottery and stone weapons attest to about 10,000 years of human presence, several excavations support the view that Rome grew from pastoral settlements on the Palatine Hill built above the area of the future Roman Forum. Between the end of the age and the beginning of the Iron age. However, none of them had yet an urban quality, nowadays, there is a wide consensus that the city was gradually born through the aggregation of several villages around the largest one, placed above the Palatine. All these happenings, which according to the excavations took place more or less around the mid of the 8th century BC. Despite recent excavations at the Palatine hill, the view that Rome has been indeed founded with an act of will as the legend suggests in the middle of the 8th century BC remains a fringe hypothesis. Traditional stories handed down by the ancient Romans themselves explain the earliest history of their city in terms of legend and myth
36.
Baths of Caracalla
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The Baths of Caracalla in Rome, Italy, were the second largest Roman public baths, or thermae, built in Rome between AD212 and 217, during the reigns of Septimius Severus and Caracalla. They would have had to install over 2,000 t of material every day for six years in order to complete it in this time. Records show that the idea for the baths were drawn up by Septimius Severus and this would allow for a longer construction timeframe. Today they are a tourist attraction, the baths remained in use until the 6th century when the complex was taken by the Ostrogoths during the Gothic War, at which time the hydraulic installations were destroyed. The bath was free and open to the public, the earthquake of 847 destroyed much of the building, along with many other Roman structures. The building was heated by a hypocaust, a system of burning coal and it was in use up to the 19th century. The Aqua Antoniniana aqueduct, a branch of the earlier Aqua Marcia and it was most likely reconstructed by Garbrecht and Manderscheid to its current place. At the 1960 Summer Olympics, the hosted the gymnastics events. The baths were the archaeological site in Rome damaged by an earthquake near LAquila in 2009. They were again damaged, though minor, in August 2016 by an earthquake in central Italy, the baths were originally ornamented with high quality sculptures. One of the statues is the colossal 4 m statue of Asclepius. The Caracalla bath complex of buildings was more a leisure centre than just a series of baths, the baths were the second to have a public library within the complex. Like other public libraries in Rome, there were two separate and equal sized rooms or buildings, one for Greek language texts and one for Latin language texts. The baths consisted of a central frigidarium measuring 55.7 by 24 m under three groin vaults 32.9 m high, a double pool tepidarium, and a caldarium 35 m in diameter, the north end of the bath building contained a natatio or swimming pool. The natatio was roofless with bronze mirrors mounted overhead to direct sunlight into the pool area, the entire bath building was on a raised platform 6 m high to allow for storage and furnaces under the building. The libraries were located in exedrae on the east and west sides of the bath complex, the entire north wall of the complex was devoted to shops. The reservoirs on the wall of the complex were fed with water from the Marcian Aqueduct. The mithraeum was approximately 23 m long and 10 m wide with a cross-vaulted ceiling, the bath complex covered approximately 25 ha
37.
Roman aqueduct
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The Romans constructed numerous aqueducts in order to bring water from often distant sources into cities and towns, supplying public baths, latrines, fountains and private households. Aqueducts also provided water for mining operations, milling, farms, Aqueducts moved water through gravity alone, along a slight downward gradient within conduits of stone, brick or concrete. Most conduits were buried beneath the ground, and followed the contours of the terrain, obstructing peaks were circumvented or, less often, tunneled through. Where valleys or lowlands intervened, the conduit was carried on bridgework, or its contents fed into high-pressure lead, ceramic or stone pipes, most aqueduct systems included sedimentation tanks, which helped reduce any water-borne debris. Sluices and castella aquae regulated the supply to individual destinations, the run-off water from aqueducts drove urban water-mills, and scoured the drains and sewers. Romes first aqueduct supplied a water fountain sited at the cattle market. By the 3rd century AD, the city had aqueducts, sustaining a population of over a million in a water-extravagant economy. Most Roman aqueducts proved reliable, and durable, some were maintained into the modern era. Methods of aqueduct surveying and construction are noted by Vitruvius in his work De Architectura, the general Frontinus gives more detail in his official report on the problems, uses and abuses of Imperial Romes public water supply. Notable examples of architecture include the supporting piers of the Aqueduct of Segovia. The reliance of ancient communities upon such water resources restricted their potential growth, by the early Imperial era, the citys aqueducts supported a population of over a million, and an extravagant water supply for public amenities had become a fundamental part of Roman life. The run-off of aqueduct water scoured the sewers of cities and towns, Water from aqueducts was also used to supply villas, ornamental urban and suburban gardens, market gardens, farms and agricultural estates, the latter being the core of Romes economy and wealth. Rome had several springs within its perimeter walls but its groundwater was notoriously unpalatable, water from the river Tiber was badly affected by pollution and waterborne diseases. The citys demand for water had probably exceeded its local supplies by 312 BC, when the citys first aqueduct. The Aqua Appia was one of two major projects of the time, the other was a military road between Rome and Capua, the first leg of the so-called Appian Way. Both projects had significant strategic value, as the Third Samnite War had been under way for thirty years by that point. The road allowed rapid troop movements, and by design or fortunate coincidence, most of the Aqua Appia ran within a buried conduit and it was fed by a spring 16. A second aqueduct, the Aqua Anio Vetus, was commissioned some forty years later and its flow was more than twice that of the Aqua Appia, and it entered the city on raised arches, supplying water to higher elevations of the city
38.
Middle Ages
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In the history of Europe, the Middle Ages or Medieval Period lasted from the 5th to the 15th century. It began with the fall of the Western Roman Empire and merged into the Renaissance, the Middle Ages is the middle period of the three traditional divisions of Western history, classical antiquity, the medieval period, and the modern period. The medieval period is subdivided into the Early, High. Population decline, counterurbanisation, invasion, and movement of peoples, the large-scale movements of the Migration Period, including various Germanic peoples, formed new kingdoms in what remained of the Western Roman Empire. In the seventh century, North Africa and the Middle East—once part of the Byzantine Empire—came under the rule of the Umayyad Caliphate, although there were substantial changes in society and political structures, the break with classical antiquity was not complete. The still-sizeable Byzantine Empire survived in the east and remained a major power, the empires law code, the Corpus Juris Civilis or Code of Justinian, was rediscovered in Northern Italy in 1070 and became widely admired later in the Middle Ages. In the West, most kingdoms incorporated the few extant Roman institutions, monasteries were founded as campaigns to Christianise pagan Europe continued. The Franks, under the Carolingian dynasty, briefly established the Carolingian Empire during the later 8th, the Crusades, first preached in 1095, were military attempts by Western European Christians to regain control of the Holy Land from Muslims. Kings became the heads of centralised nation states, reducing crime and violence, intellectual life was marked by scholasticism, a philosophy that emphasised joining faith to reason, and by the founding of universities. Controversy, heresy, and the Western Schism within the Catholic Church paralleled the conflict, civil strife. Cultural and technological developments transformed European society, concluding the Late Middle Ages, the Middle Ages is one of the three major periods in the most enduring scheme for analysing European history, classical civilisation, or Antiquity, the Middle Ages, and the Modern Period. Medieval writers divided history into periods such as the Six Ages or the Four Empires, when referring to their own times, they spoke of them as being modern. In the 1330s, the humanist and poet Petrarch referred to pre-Christian times as antiqua, leonardo Bruni was the first historian to use tripartite periodisation in his History of the Florentine People. Bruni and later argued that Italy had recovered since Petrarchs time. The Middle Ages first appears in Latin in 1469 as media tempestas or middle season, in early usage, there were many variants, including medium aevum, or middle age, first recorded in 1604, and media saecula, or middle ages, first recorded in 1625. The alternative term medieval derives from medium aevum, tripartite periodisation became standard after the German 17th-century historian Christoph Cellarius divided history into three periods, Ancient, Medieval, and Modern. The most commonly given starting point for the Middle Ages is 476, for Europe as a whole,1500 is often considered to be the end of the Middle Ages, but there is no universally agreed upon end date. English historians often use the Battle of Bosworth Field in 1485 to mark the end of the period
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Media related to Cement at Wikimedia Commons
"Cement". Encyclopædia Britannica. 5 (11th ed.). 1911.
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