Scotia is a village in Greeley County, United States. The population was 318 at the 2010 census. Scotia was founded in the 1870s. A Scottish settler suggested a literary name for Scotland. Scotia was designated the first county seat. Scotia is located at 41°28′1″N 98°42′8″W. According to the United States Census Bureau, the village has a total area of 0.35 square miles, all of it land. Scotia is located on Nebraska Highway 22; as of the census of 2010, there were 318 people, 139 households, 92 families residing in the village. The population density was 908.6 inhabitants per square mile. There were 166 housing units at an average density of 474.3 per square mile. The racial makeup of the village was 98.1% White, 0.3% African American, 0.9% Native American, 0.3% from other races, 0.3% from two or more races. Hispanic or Latino of any race were 0.6% of the population. There were 139 households of which 25.2% had children under the age of 18 living with them, 56.8% were married couples living together, 5.0% had a female householder with no husband present, 4.3% had a male householder with no wife present, 33.8% were non-families.
29.5% of all households were made up of individuals and 15.1% had someone living alone, 65 years of age or older. The average household size was 2.29 and the average family size was 2.79. The median age in the village was 42.8 years. 22% of residents were under the age of 18. The gender makeup of the village was 45.9% male and 54.1% female. As of the census of 2000, there were 308 people, 140 households, 88 families residing in the village; the population density was 889.0 people per square mile. There were 167 housing units at an average density of 482.0 per square mile. The racial makeup of the village was 94.16% White, 3.90% African American, 0.32% from other races, 1.62% from two or more races. Hispanic or Latino of any race were 0.65% of the population. There were 140 households out of which 20.7% had children under the age of 18 living with them, 57.9% were married couples living together, 4.3% had a female householder with no husband present, 37.1% were non-families. 36.4% of all households were made up of individuals and 25.7% had someone living alone, 65 years of age or older.
The average household size was 2.20 and the average family size was 2.88. In the village, the population was spread out with 22.1% under the age of 18, 5.2% from 18 to 24, 20.1% from 25 to 44, 21.1% from 45 to 64, 31.5% who were 65 years of age or older. The median age was 49 years. For every 100 females, there were 87.8 males. For every 100 females age 18 and over, there were 79.1 males. As of 2000 the median income for a household in the village was $23,750, the median income for a family was $28,750. Males had a median income of $21,563 versus $15,625 for females; the per capita income for the village was $11,871. About 5.8% of families and 7.3% of the population were below the poverty line, including 6.9% of those under the age of eighteen and 4.0% of those sixty five or over. Frank Phillips, co-founder of Phillips Petroleum Company
The United Kingdom the United Kingdom of Great Britain and Northern Ireland, sometimes referred to as Britain, is a sovereign country located off the north-western coast of the European mainland. The United Kingdom includes the island of Great Britain, the north-eastern part of the island of Ireland, many smaller islands. Northern Ireland is the only part of the United Kingdom that shares a land border with another sovereign state, the Republic of Ireland. Apart from this land border, the United Kingdom is surrounded by the Atlantic Ocean, with the North Sea to the east, the English Channel to the south and the Celtic Sea to the south-west, giving it the 12th-longest coastline in the world; the Irish Sea lies between Great Ireland. With an area of 242,500 square kilometres, the United Kingdom is the 78th-largest sovereign state in the world, it is the 22nd-most populous country, with an estimated 66.0 million inhabitants in 2017. The UK is constitutional monarchy; the current monarch is Queen Elizabeth II, who has reigned since 1952, making her the longest-serving current head of state.
The United Kingdom's capital and largest city is London, a global city and financial centre with an urban area population of 10.3 million. Other major urban areas in the UK include Greater Manchester, the West Midlands and West Yorkshire conurbations, Greater Glasgow and the Liverpool Built-up Area; the United Kingdom consists of four constituent countries: England, Scotland and Northern Ireland. Their capitals are London, Edinburgh and Belfast, respectively. Apart from England, the countries have their own devolved governments, each with varying powers, but such power is delegated by the Parliament of the United Kingdom, which may enact laws unilaterally altering or abolishing devolution; the nearby Isle of Man, Bailiwick of Guernsey and Bailiwick of Jersey are not part of the UK, being Crown dependencies with the British Government responsible for defence and international representation. The medieval conquest and subsequent annexation of Wales by the Kingdom of England, followed by the union between England and Scotland in 1707 to form the Kingdom of Great Britain, the union in 1801 of Great Britain with the Kingdom of Ireland created the United Kingdom of Great Britain and Ireland.
Five-sixths of Ireland seceded from the UK in 1922, leaving the present formulation of the United Kingdom of Great Britain and Northern Ireland. There are fourteen British Overseas Territories, the remnants of the British Empire which, at its height in the 1920s, encompassed a quarter of the world's land mass and was the largest empire in history. British influence can be observed in the language and political systems of many of its former colonies; the United Kingdom is a developed country and has the world's fifth-largest economy by nominal GDP and ninth-largest economy by purchasing power parity. It has a high-income economy and has a high Human Development Index rating, ranking 14th in the world, it was the world's first industrialised country and the world's foremost power during the 19th and early 20th centuries. The UK remains a great power, with considerable economic, military and political influence internationally, it is sixth in military expenditure in the world. It has been a permanent member of the United Nations Security Council since its first session in 1946.
It has been a leading member state of the European Union and its predecessor, the European Economic Community, since 1973. The United Kingdom is a member of the Commonwealth of Nations, the Council of Europe, the G7, the G20, NATO, the Organisation for Economic Co-operation and Development and the World Trade Organization; the 1707 Acts of Union declared that the kingdoms of England and Scotland were "United into One Kingdom by the Name of Great Britain". The term "United Kingdom" has been used as a description for the former kingdom of Great Britain, although its official name from 1707 to 1800 was "Great Britain"; the Acts of Union 1800 united the kingdom of Great Britain and the kingdom of Ireland in 1801, forming the United Kingdom of Great Britain and Ireland. Following the partition of Ireland and the independence of the Irish Free State in 1922, which left Northern Ireland as the only part of the island of Ireland within the United Kingdom, the name was changed to the "United Kingdom of Great Britain and Northern Ireland".
Although the United Kingdom is a sovereign country, Scotland and Northern Ireland are widely referred to as countries. The UK Prime Minister's website has used the phrase "countries within a country" to describe the United Kingdom; some statistical summaries, such as those for the twelve NUTS 1 regions of the United Kingdom refer to Scotland and Northern Ireland as "regions". Northern Ireland is referred to as a "province". With regard to Northern Ireland, the descriptive name used "can be controversial, with the choice revealing one's political preferences"; the term "Great Britain" conventionally refers to the island of Great Britain, or politically to England and Wales in combination. However, it is sometimes used as a loose synonym for the United Kingdom as a whole; the term "Britain" is used both as a synonym for Great Britain, as a synonym for the United Kingdom. Usage is mixed, with the BBC preferring to use Britain as shorthand only for Great Britain and the UK Government, while accepting that both terms refer to the United K
The term Norman architecture is used to categorise styles of Romanesque architecture developed by the Normans in the various lands under their dominion or influence in the 11th and 12th centuries. In particular the term is traditionally used for English Romanesque architecture; the Normans introduced large numbers of castles and fortifications including Norman keeps, at the same time monasteries, abbeys and cathedrals, in a style characterised by the usual Romanesque rounded arches and massive proportions compared to other regional variations of the style. These Romanesque styles originated in Normandy and became widespread in north western Europe in England, which contributed considerable development and has the largest number of surviving examples. At about the same time a Norman dynasty ruled in Sicily, producing a distinctive variation incorporating Byzantine and Saracen influences, known as Norman architecture, or alternatively as Sicilian Romanesque. Ancient Rome's invention of the arch is the basis of all Norman architecture.
The term may have originated with eighteenth-century antiquarians, but its usage in a sequence of styles has been attributed to Thomas Rickman in his 1817 work An Attempt to Discriminate the Styles of English Architecture from the Conquest to the Reformation which used the labels "Norman, Early English and Perpendicular". The more inclusive term romanesque was used of the Romance languages in English by 1715, was applied to architecture of the eleventh and twelfth centuries from 1819. Although Edward the Confessor built Westminster Abbey in Romanesque style just before the Conquest, still believed to be the earliest major Romanesque building in England, no significant remaining Romanesque architecture in Britain can be shown to predate the Conquest, although historians believe that many surviving "Norman" elements in buildings, nearly all churches, may well in fact be Anglo-Saxon; the Norman arch is a defining point of Norman architecture. Grand archways are designed to evoke feelings of awe and are commonly seen as the entrance to large religious buildings such as cathedrals.
Viking invaders arrived at the mouth of the river Seine in 911, at a time when Franks were fighting on horseback and Frankish lords were building castles. Over the next century the population of the territory ceded to the Vikings, now called Normans, adopted these customs as well as Christianity and the langue d'oïl. Norman barons built timber castles on earthen mounds, beginning the development of motte-and-bailey castles, great stone churches in the Romanesque style of the Franks. By 950, they were building stone; the Normans were among the most travelled peoples of Europe, exposing them to a wide variety of cultural influences which became incorporated in their art and architecture. They elaborated on the early Christian basilica plan. Longitudinal with side aisles and an apse they began to add in towers, as at the Church of Saint-Étienne]] at Caen, in 1067; this would form a model for the larger English cathedrals some 20 years later. In England, Norman nobles and bishops had influence before the Norman Conquest of 1066, Norman influences affected late Anglo-Saxon architecture.
Edward the Confessor was brought up in Normandy and in 1042 brought masons to work on the first Romanesque building in England, Westminster Abbey. In 1051 he brought in Norman knights. Following the invasion, Normans constructed motte-and-bailey castles along with churches and more elaborate fortifications such as Norman stone keeps; the buildings show massive proportions in simple geometries using small bands of sculpture. Paying attention to the concentrated spaces of capitals and round doorways as well as the tympanum under an arch; the "Norman arch" is the rounded with mouldings carved or incised onto it for decoration. Chevron patterns termed "zig-zag mouldings", were a frequent signature of the Normans; the cruciform churches had deep chancels and a square crossing tower which has remained a feature of English ecclesiastical architecture. Hundreds of parish churches were built and the great English cathedrals were founded from 1083. After a fire damaged Canterbury Cathedral in 1174 Norman masons introduced the new Gothic architecture.
Around 1191 Wells Cathedral and Lincoln Cathedral brought in the English Gothic style, Norman became a modest style of provincial building. Oxford Castle 1074: church tower doubles as a place of refuge St John's Chapel, Tower of London Durham Cathedral was the first to employ a ribbed vault system with pointed arches Winchester Cathedral Ely Cathedral Peterborough Cathedral Kilpeck Church, Herefordshire St Nicholas Church, Surrey Southwell Minster St Mary the Virgin, Oxfordshire St Swithun's in Nately Scures, Hampshire, an example of a Norman single-cell apsidal church. Norwich Cathedral St Edward's Church St Botolph's Priory, Colchester St John's Abbey, Colchester St Peter’s Church, Rutland – Norman chancel Dunstable PrioryBibliography Sedding, Edmund H. Norman Architecture in Cornwall: a handbook to old ecclesiastical architecture. With over 160 plates. London: Ward & Co. White Tower Rochester Castle Norwich Castle Colchester Castle, the largest Norman castle built and the first stone Keep in England Hedingham Castle, Essex Jew's House, Lincoln Boothby Pagnell Manor, Lincolnshire Oakham Castle, Rutland Moyse's Hall Museum Bury St Edmunds Suffolk Scotland came under early
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
A pickaxe, pick-axe, or pick is a hand tool with a hard head attached perpendicular to the handle. The head is made of metal, the handle is most wood, metal or fiberglass; the head is a spike ending in a sharp point, may curve and has a counter-weight to improve ease of use. The stronger the spike, the more the tool can pierce the surface. Rocking the embedded spike about and removing it can break up the surface; the counterweight nowadays is nearly always a second spike with a flat end for prying. The pointed edge is most used to break up rocky surfaces or other hard surfaces such as concrete or hardened dried earth; the large momentum of a heavy pickaxe on a small contact area makes it effective for this purpose. The chiseled end, if present, is used for purposes including cutting through roots. Used as agricultural tools as far back as prehistoric cultures, picks have served for tasks ranging from traditional mining to warfare; the design has evolved into other tools such as the plough and the mattock.
In prehistoric times a large shed deer antler from a suitable species was cut down to its shaft and its lowest tine and used as a one-pointed pick, with it sometimes a large animal's shoulder blade as a crude shovel. During war in medieval times, the pickaxe was used as a weapon. Unicode 5.2 in the Miscellaneous Symbols block introduces the glyph ⛏, representable in HTML as ⛏. The Oxford Dictionary of English states that both "pick" and "pickaxe" have the same meaning, that being a tool with a long handle at right angles to a curved iron or steel bar with a point at one end and a chisel or point at the other, used for breaking up hard ground or rock; the term "pickaxe" is a folk etymology alteration of Middle-English picas via Anglo-French piceis, Old French pocois, directly from Medieval Latin picosa "pick", related to Latin picus "woodpecker". Though modern picks feature a head with both a pointed end and an adze-like flattened blade on the other end, current spelling is influenced by "axe", "pickaxe", "pick-axe", or sometimes just "pick" cover any and all versions of the tool.
A pickaxe handle without the head is sometimes used unofficially, as a baton: for example it is sometimes used as a baton in the British Army. In The Grapes of Wrath by John Steinbeck, pick handles featured prominently as a weapon used against the migrant farmers. A normal pickaxe handle is made of ash or hickory wood and is about three feet long and weighs about 2.5 pounds. British Army pickaxe handles must, by regulation, be three feet long, for use in measuring in the field. New variant designs are: With a plastic casing on the thick end. Made of carbon fibreIn former times they were sometimes made with a steel casing on the thick end. Mattock Ice axe
Mining is the extraction of valuable minerals or other geological materials from the earth from an ore body, vein, reef or placer deposit. These deposits form a mineralized package, of economic interest to the miner. Ores recovered by mining include metals, oil shale, limestone, dimension stone, rock salt, potash and clay. Mining is required to obtain any material that cannot be grown through agricultural processes, or feasibly created artificially in a laboratory or factory. Mining in a wider sense includes extraction of any non-renewable resource such as petroleum, natural gas, or water. Mining of stones and metal has been a human activity since pre-historic times. Modern mining processes involve prospecting for ore bodies, analysis of the profit potential of a proposed mine, extraction of the desired materials, final reclamation of the land after the mine is closed. De Re Metallica, Georgius Agricola, 1550, Book I, Para. 1Mining operations create a negative environmental impact, both during the mining activity and after the mine has closed.
Hence, most of the world's nations have passed regulations to decrease the impact. Work safety has long been a concern as well, modern practices have improved safety in mines. Levels of metals recycling are low. Unless future end-of-life recycling rates are stepped up, some rare metals may become unavailable for use in a variety of consumer products. Due to the low recycling rates, some landfills now contain higher concentrations of metal than mines themselves. Since the beginning of civilization, people have used stone and metals found close to the Earth's surface; these were used to make early weapons. Flint mines have been found in chalk areas where seams of the stone were followed underground by shafts and galleries; the mines at Grimes Graves and Krzemionki are famous, like most other flint mines, are Neolithic in origin. Other hard rocks mined or collected for axes included the greenstone of the Langdale axe industry based in the English Lake District; the oldest-known mine on archaeological record is the Ngwenya Mine in Swaziland, which radiocarbon dating shows to be about 43,000 years old.
At this site Paleolithic humans mined hematite to make the red pigment ochre. Mines of a similar age in Hungary are believed to be sites where Neanderthals may have mined flint for weapons and tools. Ancient Egyptians mined malachite at Maadi. At first, Egyptians used the bright green malachite stones for ornamentations and pottery. Between 2613 and 2494 BC, large building projects required expeditions abroad to the area of Wadi Maghareh in order to secure minerals and other resources not available in Egypt itself. Quarries for turquoise and copper were found at Wadi Hammamat, Tura and various other Nubian sites on the Sinai Peninsula and at Timna. Mining in Egypt occurred in the earliest dynasties; the gold mines of Nubia were among the largest and most extensive of any in Ancient Egypt. These mines are described by the Greek author Diodorus Siculus, who mentions fire-setting as one method used to break down the hard rock holding the gold. One of the complexes is shown in one of the earliest known maps.
The miners crushed the ore and ground it to a fine powder before washing the powder for the gold dust. Mining in Europe has a long history. Examples include the silver mines of Laurium. Although they had over 20,000 slaves working them, their technology was identical to their Bronze Age predecessors. At other mines, such as on the island of Thassos, marble was quarried by the Parians after they arrived in the 7th century BC; the marble was shipped away and was found by archaeologists to have been used in buildings including the tomb of Amphipolis. Philip II of Macedon, the father of Alexander the Great, captured the gold mines of Mount Pangeo in 357 BC to fund his military campaigns, he captured gold mines in Thrace for minting coinage producing 26 tons per year. However, it was the Romans who developed large scale mining methods the use of large volumes of water brought to the minehead by numerous aqueducts; the water was used for a variety of purposes, including removing overburden and rock debris, called hydraulic mining, as well as washing comminuted, or crushed and driving simple machinery.
The Romans used hydraulic mining methods on a large scale to prospect for the veins of ore a now-obsolete form of mining known as hushing. They built numerous aqueducts to supply water to the minehead. There, the water stored in large tanks; when a full tank was opened, the flood of water sluiced away the overburden to expose the bedrock underneath and any gold veins. The rock was worked upon by fire-setting to heat the rock, which would be quenched with a stream of water; the resulting thermal shock cracked the rock, enabling it to be removed by further streams of water from the overhead tanks. The Roman miners used similar methods to work cassiterite deposits in Cornwall and lead ore in the Pennines; the methods had been developed by the Romans in Spain in 25 AD to exploit large alluvial gold deposits, the largest site being at Las Medulas, where seven long aqueducts tapped local rivers and sluiced the deposits. Spain was one of the most important mining regions, but all regions of the Roman Empire were exploited.
In Great Britain the natives had mined minerals for millennia, but after the Roman conquest, the scale of the operations increased as the Romans needed Britannia's resources gold, silver
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