A cement is a binder, a substance used for construction that sets and adheres to other materials to bind them together. Cement is used on its own, but rather to bind sand and gravel together. Cement mixed with fine aggregate produces mortar for masonry, or with sand and gravel, produces concrete. Cement is the most used material in existence and is only behind water as the planet's most-consumed resource. Cements used in construction are inorganic lime or calcium silicate based, can be characterized as either hydraulic or non-hydraulic, depending on the ability of the cement to set in the presence of water. Non-hydraulic cement does not set under water. Rather, it sets as it reacts with carbon dioxide in the air, it is resistant to attack by chemicals after setting. Hydraulic cements set and become adhesive due to a chemical reaction between the dry ingredients and water; the chemical reaction results in mineral hydrates that are not water-soluble and so are quite durable in water and safe from chemical attack.
This allows setting in wet conditions or under water and further protects the hardened material from chemical attack. The chemical process for hydraulic cement found by ancient Romans used volcanic ash with added lime; the word "cement" can be traced back to the Roman term opus caementicium, used to describe masonry resembling modern concrete, made from crushed rock with burnt lime as binder. The volcanic ash and pulverized brick supplements that were added to the burnt lime, to obtain a hydraulic binder, were referred to as cementum, cimentum, cäment, cement. In modern times, organic polymers are sometimes used as cements in concrete. Non-hydraulic cement, such as slaked lime, hardens by carbonation in the presence of carbon dioxide, present in the air. First calcium oxide is produced from calcium carbonate by calcination at temperatures above 825 °C for about 10 hours at atmospheric pressure: CaCO3 → CaO + CO2The calcium oxide is spent mixing it with water to make slaked lime: CaO + H2O → Ca2Once the excess water is evaporated, the carbonation starts: Ca2 + CO2 → CaCO3 + H2OThis reaction takes time, because the partial pressure of carbon dioxide in the air is low.
The carbonation reaction requires that the dry cement be exposed to air, so the slaked lime is a non-hydraulic cement and cannot be used under water. This process is called the lime cycle. Conversely, hydraulic cement hardens by hydration. Hydraulic cements are made of a mixture of silicates and oxides, the four main components being: Belite; the silicates are responsible for the cement's mechanical properties—the tricalcium aluminate and brownmillerite are essential for formation of the liquid phase during the kiln sintering. The chemistry of these reactions is not clear and is still the object of research; the earliest known occurrence of cement is from twelve million 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; these ancient deposits were investigated in the 1970s. Cement, chemically speaking, is a product that includes lime as the primary curing ingredient, but is far from the first material used for cementation.
The Babylonians and Assyrians used bitumen to bind together burnt alabaster slabs. In Egypt stone blocks were cemented together with a mortar made of sand and burnt gypsum, which contained calcium carbonate. Lime was used by the ancient Greeks. There is evidence that the Minoans of Crete used crushed potshards as an artificial pozzolan for hydraulic cement. Nobody knows who first discovered that a combination of hydrated non-hydraulic lime and a pozzolan produces a hydraulic mixture —but such concrete was used by the Ancient Macedonians, three centuries on a large scale by Roman engineers. There is... a kind of powder. It is found in the neighborhood of Baiae and in the country belonging to the towns round about Mt. Vesuvius; this substance when mixed with lime and rubble not only lends strength to buildings of other kinds, but when piers of it are constructed in the sea, they set hard under water. The Greeks used volcanic tuff from the island of Thera as their pozzolan and the Romans used crushed volcanic ash with lime.
This mixture could set under water. The material was called pozzolana from the town of Pozzuoli, west of Naples where volcanic ash was extracted. In the absence of pozzolanic ash, the Romans used powdered brick or pottery as a substitute and they may have used crushed tiles for this purpose before discovering natural sources near Rome; the huge dome of the Pantheon in Rome and the massive Baths of Caracalla are examples of ancient structures made from these concretes, many of which still stand. The vast system of Roman aqueducts made extensive use of hydraulic cement. Roman concrete was used on the outside of buildings; the normal technique was to use brick facing material as the formwork for an infill of mortar mixed with an aggregate of broken pieces of stone, potsherds, recycled chunks of concrete, or other building ru
Calcium hydroxide is an inorganic compound with the chemical formula Ca2. It is a colorless crystal or white powder and is obtained when quicklime is mixed, or slaked with water, it has many names including hydrated lime, caustic lime, builders' lime, slack lime, cal, or pickling lime. Calcium hydroxide is used in many applications, including food preparation, where it has been identified as E number E526. Limewater is the common name for a saturated solution of calcium hydroxide. Calcium hydroxide is insoluble in water, with a solubility product Ksp of 5.5 × 10−6. It is large enough that its solutions are basic according to the following reaction: Ca2 → Ca2+ + 2 OH−At ambient temperature. Calcium hydroxide dissolves in pure water to produce an alkaline solution with a pH of about 12.4. Calcium hydroxide solutions can cause chemical burns. At high pH value, its solubility drastically decreases; this behavior is relevant to cement pastes. Aqueous solutions of calcium hydroxide are called limewater and are medium strength bases that reacts with acids and can attack some metals such as aluminium while protecting other metals from corrosion such as iron and steel by passivation of their surface.
Limewater turns milky in the presence of carbon dioxide due to formation of calcium carbonate, a process called carbonatation:for example lime water Ca2 + CO2 → CaCO3 + H2OWhen heated to 512 °C, the partial pressure of water in equilibrium with calcium hydroxide reaches 101 kPa, which decomposes calcium hydroxide into calcium oxide and water. Ca2 → CaO + H2O Calcium hydroxide adopts a polymeric structure; the structure is identical to that of Mg2. Strong hydrogen bonds exist between the layers. Calcium hydroxide is produced commercially by treating lime with water: CaO + H2O → Ca2In the laboratory it can be prepared by mixing aqueous solutions of calcium chloride and sodium hydroxide; the mineral form, portlandite, is rare but can be found in some volcanic and metamorphic rocks. It has been known to arise in burning coal dumps; the positively charged. The solubility of calcium hydroxide at 70 °C is about half of its value at 25 °C; the reason for this rather uncommon phenomenon is that the dissolution of calcium hydroxide in water is an exothermic process, adheres to Le Chatelier's principle.
A lowering of temperature thus favours the elimination of the heat liberated through the process of dissolution and increases the equilibrium constant of dissolution of Ca2, so increase its solubility at low temperature. This counter-intuitive temperature dependence of the solubility is referred to as "retrograde" or "inverse" solubility; the variably hydrated phases of calcium sulfate exhibit a retrograde solubility for the same reason because their dissolution reactions are exothermic. One significant application of calcium hydroxide is in water and sewage treatment, it forms a fluffy charged solid that aids in the removal of smaller particles from water, resulting in a clearer product. This application is enabled by the low cost and low toxicity of calcium hydroxide, it is used in fresh water treatment for raising the pH of the water so that pipes will not corrode where the base water is acidic, because it is self-regulating and does not raise the pH too much. It is used in the preparation of ammonia gas, using the following reaction: Ca2 + 2NH4Cl → 2NH3 + CaCl2 + 2H2OAnother large application is in the paper industry, where it is an intermediate in the reaction in the production of sodium hydroxide.
This conversion is part of the causticizing step in the Kraft process for making pulp. In the causticizing operation, burned lime is added to green liquor, a solution of sodium carbonate and sodium sulfate produced by dissolving smelt, the molten form of these chemicals from the recovery furnace; because of its low toxicity and the mildness of its basic properties, slaked lime is used in the food industry to: clarify raw juice from sugarcane or sugar beets in the sugar industry, process water for alcoholic beverages and soft drinks pickle cucumbers and other foods make Chinese century eggs in maize preparation: removes the cellulose hull of maize kernels clear a brine of carbonates of calcium and magnesium in the manufacture of salt for food and pharmaceutical uses fortify fruit drinks, such as orange juice, infant formula aid digestion substitute for baking soda in making papadam. Remove carbon dioxide from controlled atmosphere produce storage rooms. In Spanish, calcium hydroxide is called cal.
Maize cooked with cal becomes hominy, which increases the bioavailability of niacin, it is considered tastier and easier to digest. In chewing coca leaves, calcium hydroxide is chewed alongside to keep the alkaloid stimulants chemically available for absorption by the body. Native Americans traditionally chewed tobacco leaves with calcium hydroxide derived from burnt mollusc shells to enhance the effects, it has been used by some indigenous American tribes as an ingredient in yopo, a psychedelic snuff prepared from the beans of some Anadenanthera species. Calcium hydroxide is added to a bundle of areca nut and
Clay is a finely-grained natural rock or soil material that combines one or more clay minerals with possible traces of quartz, metal oxides and organic matter. Geologic clay deposits are composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure. Clays are plastic due to particle size and geometry as well as water content, become hard and non–plastic upon drying or firing. Depending on the soil's content in which it is found, clay can appear in various colours from white to dull grey or brown to deep orange-red. Although many occurring deposits include both silts and clay, clays are distinguished from other fine-grained soils by differences in size and mineralogy. Silts, which are fine-grained soils that do not include clay minerals, tend to have larger particle sizes than clays. There is, some overlap in particle size and other physical properties; the distinction between silt and clay varies by discipline. Geologists and soil scientists consider the separation to occur at a particle size of 2 µm, sedimentologists use 4–5 μm, colloid chemists use 1 μm.
Geotechnical engineers distinguish between silts and clays based on the plasticity properties of the soil, as measured by the soils' Atterberg limits. ISO 14688 grades clay particles as being smaller than 2 silt particles as being larger. Mixtures of sand and less than 40% clay are called loam. Loam is used as a building material. Clay minerals form over long periods of time as a result of the gradual chemical weathering of rocks silicate-bearing, by low concentrations of carbonic acid and other diluted solvents; these solvents acidic, migrate through the weathering rock after leaching through upper weathered layers. In addition to the weathering process, some clay minerals are formed through hydrothermal activity. There are two types of clay deposits: secondary. Primary clays remain at the site of formation. Secondary clays are clays that have been transported from their original location by water erosion and deposited in a new sedimentary deposit. Clay deposits are associated with low energy depositional environments such as large lakes and marine basins.
Depending on the academic source, there are three or four main groups of clays: kaolinite, montmorillonite-smectite and chlorite. Chlorites are not always considered to be a clay, sometimes being classified as a separate group within the phyllosilicates. There are 30 different types of "pure" clays in these categories, but most "natural" clay deposits are mixtures of these different types, along with other weathered minerals. Varve is clay with visible annual layers, which are formed by seasonal deposition of those layers and are marked by differences in erosion and organic content; this type of deposit is common in former glacial lakes. When fine sediments are delivered into the calm waters of these glacial lake basins away from the shoreline, they settle to the lake bed; the resulting seasonal layering is preserved in an distribution of clay sediment banding. Quick clay is a unique type of marine clay indigenous to the glaciated terrains of Norway, Northern Ireland, Sweden, it is a sensitive clay, prone to liquefaction, involved in several deadly landslides.
Powder X-ray diffraction can be used to identify clays. The physical and reactive chemical properties can be used to help elucidate the composition of clays. Clays exhibit plasticity. However, when dry, clay becomes firm and when fired in a kiln, permanent physical and chemical changes occur; these changes convert the clay into a ceramic material. Because of these properties, clay is used for making pottery, both utilitarian and decorative, construction products, such as bricks and floor tiles. Different types of clay, when used with different minerals and firing conditions, are used to produce earthenware and porcelain. Prehistoric humans discovered the useful properties of clay; some of the earliest pottery shards recovered are from Japan. They are associated with the Jōmon culture and deposits they were recovered from have been dated to around 14,000 BC. Clay tablets were the first known writing medium. Scribes wrote by inscribing them with cuneiform script using a blunt reed called a stylus. Purpose-made clay balls were used as sling ammunition.
Clays sintered in fire were the first form of ceramic. Bricks, cooking pots, art objects, smoking pipes, musical instruments such as the ocarina can all be shaped from clay before being fired. Clay is used in many industrial processes, such as paper making, cement production, chemical filtering; until the late 20th century, bentonite clay was used as a mold binder in the manufacture of sand castings. Clay, being impermeable to water, is used where natural seals are needed, such as in the cores of dams, or as a barrier in landfills against toxic seepage. Studies in the early 21st century have investigated clay's absorption capacities in various applications, such as the removal of heavy metals from waste water and air purification. Traditional uses of clay as medicine goes back to prehistoric times. An example is Armenian bole, used to soothe an upset stomach; some animals such as parrots and pigs ingest clay for similar reasons. Kaolin clay and attapulgite have been used as anti-diarrheal medicines.
Clay as the defining ingredient of loam is one of the oldest building materials on Earth, among other
Aluminium oxide or aluminum oxide is a chemical compound of aluminium and oxygen with the chemical formula Al2O3. It is the most occurring of several aluminium oxides, identified as aluminium oxide, it is called alumina and may be called aloxide, aloxite, or alundum depending on particular forms or applications. It occurs in its crystalline polymorphic phase α-Al2O3 as the mineral corundum, varieties of which form the precious gemstones ruby and sapphire. Al2O3 is significant in its use to produce aluminium metal, as an abrasive owing to its hardness, as a refractory material owing to its high melting point. Corundum is the most common occurring crystalline form of aluminium oxide. Rubies and sapphires are gem-quality forms of corundum, which owe their characteristic colors to trace impurities. Rubies are given their characteristic deep red color and their laser qualities by traces of chromium. Sapphires come in different colors given by various other impurities, such as titanium. Al2O3 is an electrical insulator but has a high thermal conductivity for a ceramic material.
Aluminium oxide is insoluble in water. In its most occurring crystalline form, called corundum or α-aluminium oxide, its hardness makes it suitable for use as an abrasive and as a component in cutting tools. Aluminium oxide is responsible for the resistance of metallic aluminium to weathering. Metallic aluminium is reactive with atmospheric oxygen, a thin passivation layer of aluminium oxide forms on any exposed aluminium surface; this layer protects the metal from further oxidation. The thickness and properties of this oxide layer can be enhanced using a process called anodising. A number of alloys, such as aluminium bronzes, exploit this property by including a proportion of aluminium in the alloy to enhance corrosion resistance; the aluminium oxide generated by anodising is amorphous, but discharge assisted oxidation processes such as plasma electrolytic oxidation result in a significant proportion of crystalline aluminium oxide in the coating, enhancing its hardness. Aluminium oxide was taken off the United States Environmental Protection Agency's chemicals lists in 1988.
Aluminium oxide is on the EPA's Toxics Release Inventory list. Aluminium oxide is an amphoteric substance, meaning it can react with both acids and bases, such as hydrofluoric acid and sodium hydroxide, acting as an acid with a base and a base with an acid, neutralising the other and producing a salt. Al2O3 + 6 HF → 2 AlF3 + 3 H2O Al2O3 + 2 NaOH + 3 H2O → 2 NaAl4 The most common form of crystalline aluminium oxide is known as corundum, the thermodynamically stable form; the oxygen ions form a nearly hexagonal close-packed structure with the aluminium ions filling two-thirds of the octahedral interstices. Each Al3+ center is octahedral. In terms of its crystallography, corundum adopts a trigonal Bravais lattice with a space group of R3c; the primitive cell contains two formula units of aluminium oxide. Aluminium oxide exists in other, phases, including the cubic γ and η phases, the monoclinic θ phase, the hexagonal χ phase, the orthorhombic κ phase and the δ phase that can be tetragonal or orthorhombic.
Each has properties. Cubic γ-Al2O3 has important technical applications; the so-called β-Al2O3 proved to be NaAl11O17. Molten aluminium oxide near the melting temperature is 2/3 tetrahedral, 1/3 5-coordinated, with little octahedral Al-O present. Around 80% of the oxygen atoms are shared among three or more Al-O polyhedra, the majority of inter-polyhedral connections are corner-sharing, with the remaining 10–20% being edge-sharing; the breakdown of octahedra upon melting is accompanied by a large volume increase, the density of the liquid close to its melting point is 2.93 g/cm3. The structure of molten alumina is temperature dependent and the fraction of 5- and 6-fold aluminium increases during cooling, at the expense of tetrahedral AlO4 units, approaching the local structural arrangements found in amorphous alumina. Aluminium hydroxide minerals are the main component of the principal ore of aluminium. A mixture of the minerals comprise bauxite ore, including gibbsite and diaspore, along with impurities of iron oxides and hydroxides and clay minerals.
Bauxites are found in laterites. Bauxite is purified by the Bayer process: Al2O3 + H2O + NaOH → NaAl4 Al3 + NaOH → NaAl4Except for SiO2, the other components of bauxite do not dissolve in base. Upon filtering the basic mixture, Fe2O3 is removed; when the Bayer liquor is cooled, Al3 precipitates. NaAl4 → NaOH + Al3The solid Al3 Gibbsite is calcined to give aluminium oxide: 2 Al3 → Al2O3 + 3 H2OThe product aluminium oxide tends to be multi-phase, i.e. consisting of several phases of aluminium oxide rather than corundum. The production process can therefore be optimized to produce a tailored product; the type of phases present affects, for example, the solubility and pore structure of the aluminium oxide product which, in turn, affects the cost of aluminium production and pollution control. Known as alundum or aloxite in the mining and materials science communities, aluminium oxide finds wide use. Annual world production of aluminium oxide in 2015 was 115 million tonnes, over 90% of, used in the manufacture of aluminium metal.
The major uses of speciali
Repointing is the process of renewing the pointing, the external part of mortar joints, in masonry construction. Over time and decay cause voids in the joints between masonry units in bricks, allowing the undesirable entrance of water. Water entering through these voids can cause significant damage through frost weathering and from salt dissolution and deposition. Repointing is called pointing, or pointing up, although these terms more properly refer to the finishing step in new construction. Traditionally, the first mortar was made with sand, which would make lime putty. Starting in the early 20th century, masons started using Portland Cement, a strong, fast drying cement, not purely on its own though. Masonry cement made its appearance in the 1930s, a combination of Portland cement and ground limestone. Before starting any actual work, building owners examine the masonry units and the techniques used in the original construction, they try to identify the true problem they are facing and find out what were the causes of the deterioration or cracks.
If there are cracks or problems in the actual bricks or stone masonry there could be a larger problem that needs to be addressed. If there is a larger issue, repointing may cause further damage. If a historic structure needs repointing, building owners hire an architectural historian or conservator to help pinpoint the issues. If the crack is smaller than 2mm and not causing any major defects, than it is better to leave it and not repoint, it is common to see cracking along old repairs because of the shrinkage of hard mortar and the seasonal flexing along the joint. Examining the structure before working will help establish the strength and permeability of the original mortar in order to match the new, it helps to establish what the original components of the old mortar are in order to find the best match. It is essential that the mortar used for repointing have similar performance characteristics to the original mortar used in a building; such performance characteristics include permeability, compressive strength, coefficient of thermal expansion.
The mortar must have greater vapor permeability and softer compressive strength than the original mortar. The mortar should not be stronger than the masonry units because it will not have give. Rather than the mortar relieving the stress, the masonry units will, which will cause further damage to the masonry unit, such as cracking or spalling; this is. This will be more strenuous to fix. So for example, if a soft lime-based mortar was used, the most appropriate repointing mortar is to contain a large amount of lime. An architectural conservator can perform a mortar analysis in order to make recommendations for replacement mortar, both physically and aesthetically compatible with the building. There are two common methods of analyzing mortar; the first is called "wet chemical." This is when a sample of the mortar is mixed with a dilute acid. The mortar will be broken down, the type of mortar and sand used will be determined by the color and the texture. Another form of "wet chemical" analysis is the same process but the carbon dioxide gas, given off by the digestion will be collected and the type of mortar will be determined by its volume.
The amounts of each component will be determined. The second method to analyzing mortar is "instrumental." There are several different forms of "instrumental" analysis. This is; this process can provide more information than "wet-chemical" examination. Other examples of "instrumental analysis are scanning electron microscopy, X-ray diffraction, atomic absorption spectroscopy. Analysis is not based on lab work, however. There are important performances of mortar that can not be determined in a lab: original water content, rate of curing, weather conditions during original construction, method of mixing and placing the mortar, cleanliness of sand, it is important to match the color of the mortar. However, in the past lime mortar tended to be mixed on site with whatever sand was locally available. Since the sand influences the color of the lime mortar, colors of pointing mortar can vary from district to district. Weathering of the new mortar will match it to the old mortar; the tooling should match the tooling of the historic mortar.
Again, before starting any work, the methods and materials for the repointing will be applied in a test panel. A test panel is an area on the structure out of plain sight where the owner or conservator can test the repointing methods they will use, the color of the mortar, the skills of the mason; this will be good to determine the types of tools that should be used, which will be discussed in the next paragraph. For a brick structure, the panel should not be any bigger than 3' x 3'. For other masonry units, the test panel can be a little larger, it is important to pick the right season to do the repointing. High or low temperatures can cause rapid drying which can have negative effects on the mortar, masonry units, the structure itself. After examination, the next step is cutting away the old mortar; the old mortar is removed to a depth equal to or more than the width of the joint, or to the point where sound mortar is reached. Removal of old mortar between joints is done to avoid damage to masonry units.
On buildings with soft materials, such as under-fired brick, lime mortar, or terra cotta, removal by hand is the most effective to
A brick is building material used to make walls and other elements in masonry construction. Traditionally, the term brick referred to a unit composed of clay, but it is now used to denote any rectangular units laid in mortar. A brick can be composed of clay-bearing soil and lime, or concrete materials. Bricks are produced in numerous classes, types and sizes which vary with region and time period, are produced in bulk quantities. Two basic categories of bricks are non-fired bricks. Block is a similar term referring to a rectangular building unit composed of similar materials, but is 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, have been used since circa 4000 BC. Air-dried bricks known as mudbricks, have a history older than fired bricks, have an additional ingredient of a mechanical binder such as straw. Bricks are laid in courses and numerous patterns known as bonds, collectively known as brickwork, may be laid in various kinds of mortar to hold the bricks together to make a durable structure.
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 made from shaped mud and dating before 7500 BC, were found at Tell Aswad, in the upper Tigris region and in southeast Anatolia close to Diyarbakir; the South Asian inhabitants of Mehrgarh constructed, lived in, airdried mudbrick houses between 7000–3300 BC. Other more recent findings, dated between 7,000 and 6,395 BC, come from Jericho, Catal Hüyük, the ancient Egyptian fortress of Buhen, the ancient Indus Valley cities of Mohenjo-daro and Mehrgarh. Ceramic, or fired brick was used as early as 3000 BC in early Indus Valley cities like Kalibangan; the earliest fired bricks appeared in Neolithic China around 4400 BC at Chengtoushan, a walled settlement of the Daxi culture. These bricks were made of red clay, fired on all sides to above 600 °C, used as flooring for houses. By the Qujialing period, fired bricks were being used to pave roads and as building foundations at Chengtoushan.
Bricks continued to be used during 2nd millennium BC at a site near Xi'an. Fired bricks were found in Western Zhou ruins; the carpenter's manual Yingzao Fashi, published in 1103 at the time of the Song dynasty described the brick making process and glazing techniques in use. Using the 17th-century encyclopaedic text Tiangong Kaiwu, historian Timothy Brook outlined the brick production process of Ming Dynasty China: "...the kilnmaster had to make sure that the temperature inside the kiln stayed at a level that caused the clay to shimmer with the colour of molten gold or silver. He had to know when to quench the kiln with water so as to produce the surface glaze. To anonymous labourers fell the less skilled stages of brick production: mixing clay and water, driving oxen over the mixture to trample it into a thick paste, scooping the paste into standardised wooden frames, smoothing the surfaces with a wire-strung bow, removing them from the frames, printing the fronts and backs with stamps that indicated where the bricks came from and who made them, loading the kilns with fuel, stacking the bricks in the kiln, removing them to cool while the kilns were still hot, bundling them into pallets for transportation.
It was hot, filthy work." Early civilisations around the Mediterranean adopted the use of fired bricks, including the Ancient Greeks and Romans. The Roman legions operated mobile kilns, built large brick structures throughout the Roman Empire, stamping the bricks with the seal of the legion. 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 brick architecture, known as brick Gothic flourished in places that lacked indigenous sources of rocks. Examples of this architectural style can be found in modern-day Denmark, Germany and Russia; this style evolved into Brick Renaissance as the stylistic changes associated with the Italian Renaissance spread to northern Europe, leading to the adoption of Renaissance elements into brick building. A clear distinction between the two styles only developed at the transition to Baroque architecture. In Lübeck, for example, Brick Renaissance is recognisable in buildings equipped with terracotta reliefs by the artist Statius von Düren, active at Schwerin and Wismar.
Long-distance bulk transport of bricks and other construction equipment remained prohibitively expensive until the development of modern transportation infrastructure, with the construction of canal and railways. 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 preferred as building material to stone in areas where the stone was available, it was at this time in London that bright red brick was chosen for construction to make the buildings more visible in the heavy fog and to help prevent traffic accidents. The transition from the traditional method of production known as hand-moulding to a mechanised form of mass-production took place during the first half of the nineteenth century; the first successful brick-making machine was patented by Henry Clayton, employed at the
Babylonia was an ancient Akkadian-speaking state and cultural area based in central-southern Mesopotamia. A small Amorite-ruled state emerged in 1894 BC, which contained the minor administrative town of Babylon, it was a small provincial town during the Akkadian Empire but expanded during the reign of Hammurabi in the first half of the 18th century BC and became a major capital city. During the reign of Hammurabi and afterwards, Babylonia was called "the country of Akkad", a deliberate archaism in reference to the previous glory of the Akkadian Empire, it was involved in rivalry with the older state of Assyria to the north and Elam to the east in Ancient Iran. Babylonia became the major power in the region after Hammurabi created a short-lived empire, succeeding the earlier Akkadian Empire, Third Dynasty of Ur, Old Assyrian Empire; the Babylonian Empire, however fell apart after the death of Hammurabi and reverted to a small kingdom. Like Assyria, the Babylonian state retained the written Akkadian language for official use, despite its Northwest Semitic-speaking Amorite founders and Kassite successors, who spoke a language isolate, not being native Mesopotamians.
It retained the Sumerian language for religious use, but by the time Babylon was founded, this was no longer a spoken language, having been wholly subsumed by Akkadian. The earlier Akkadian and Sumerian traditions played a major role in Babylonian and Assyrian culture, the region would remain an important cultural center under its protracted periods of outside rule; the earliest mention of the city of Babylon can be found in a clay tablet from the reign of Sargon of Akkad, dating back to the 23rd century BC. Babylon was a religious and cultural centre at this point and neither an independent state nor a large city. After the collapse of the Akkadian Empire, the south Mesopotamian region was dominated by the Gutian people for a few decades before the rise of the Third Dynasty of Ur, which restored order to the region and which, apart from northern Assyria, encompassed the whole of Mesopotamia, including the town of Babylon. Mesopotamia had enjoyed a long history prior to the emergence of Babylon, with Sumerian civilisation emerging in the region c. 3500 BC, the Akkadian-speaking people appearing by the 30th century BC.
During the 3rd millennium BC, an intimate cultural symbiosis occurred between Sumerian and Akkadian-speakers, which included widespread bilingualism. The influence of Sumerian on Akkadian and vice versa is evident in all areas, from lexical borrowing on a massive scale, to syntactic and phonological convergence; this has prompted scholars to refer to Sumerian and Akkadian in the third millennium as a sprachbund. Akkadian replaced Sumerian as the spoken language of Mesopotamia somewhere around the turn of the third and the second millennium BC. From c. 3500 BC until the rise of the Akkadian Empire in the 24th century BC, Mesopotamia had been dominated by Sumerian cities and city states, such as Ur, Uruk, Isin, Adab, Gasur, Hamazi, Akshak and Umma, although Semitic Akkadian names began to appear on the king lists of some of these states between the 29th and 25th centuries BC. Traditionally, the major religious center of all Mesopotamia was the city of Nippur where the god Enlil was supreme, it would remain so until replaced by Babylon during the reign of Hammurabi in the mid-18th century BC.
The Akkadian Empire saw the Akkadian Semites and Sumerians of Mesopotamia unite under one rule, the Akkadians attain ascendancy over the Sumerians and indeed come to dominate much of the ancient Near East. The empire disintegrated due to economic decline, climate change and civil war, followed by attacks by the Gutians from the Zagros Mountains. Sumer rose up again with the Third Dynasty of Ur in the late 22nd century BC, ejected the Gutians from southern Mesopotamia, they seem to have gained ascendancy over much of the territory of the Akkadian kings of Assyria in northern Mesopotamia for a time. Followed by the collapse of the Sumerian "Ur-III" dynasty at the hands of the Elamites in 2002 BC, the Amorites, a foreign Northwest Semitic-speaking people, began to migrate into southern Mesopotamia from the northern Levant gaining control over most of southern Mesopotamia, where they formed a series of small kingdoms, while the Assyrians reasserted their independence in the north; the states of the south were unable to stem the Amorite advance, for a time may have relied on their fellow Akkadians in Assyria for protection.
King Ilu-shuma of the Old Assyrian Empire in a known inscription describes his exploits to the south as follows: The freedom of the Akkadians and their children I established. I purified their copper. I established their freedom from the border of the marshes and Ur and Nippur and Kish, Der of the goddess Ishtar, as far as the City of. Past scholars extrapolated from this text that it means he defeated the invading Amorites to the south and Elamites to the east, but there is no explicit record of that, some scholars believe the Assyrian kings were giving preferential trade agreements to the south; these policies were continued by Ikunum. However, when Sargon I s