Butte is the county seat of Silver Bow County, United States. In 1977, the city and county governments consolidated to form the sole entity of Butte-Silver Bow; the city covers 718 square miles, according to the 2010 census, has a population of 33,503, making it Montana's fifth largest city. It is served by Bert Mooney Airport with airport code BTM. Established in 1864 as a mining camp in the northern Rocky Mountains on the Continental Divide, Butte experienced rapid development in the late-nineteenth century, was Montana's first major industrial city. In its heyday between the late-nineteenth and early-twentieth centuries, it was one of the largest copper boomtowns in the American West. Employment opportunities in the mines attracted surges of Asian and European immigrants the Irish. Butte was the site of various historical events involving its mining industry and active labor unions and Socialist politics, the most famous of, the labor riot of 1914. Despite the dominance of the Anaconda Copper Mining Company, Butte was never a company town.
Other major events in the city's history include the 1917 Speculator Mine disaster, the largest hard rock mining disaster in world history. Over the course of its history, Butte's mining and smelting operations generated an excess of $48 billion worth of ore, but resulted in numerous environmental implications for the city: The upper Clark Fork River, with headwaters at Butte, is the largest Superfund site in the United States, the city is home to the Berkeley Pit. In the late-twentieth century, cleanup efforts from the EPA were instated, the Butte Citizens Technical Environmental Committee was established in 1984. In the 21st century, efforts at interpreting and preserving Butte's heritage are addressing both the town's historical significance and the continuing importance of mining to its economy and culture; the city's Uptown Historic District, on the National Register of Historic Places, is one of the largest National Historic Landmark Districts in the United States, containing nearly 6,000 contributing properties.
The city is home to Montana Tech, a public engineering and technical university. Prior to Butte's formal establishment in 1864, the area consisted of a mining camp that had developed in the early 1860s; the city is located in the Silver Bow Creek Valley, a natural bowl sitting high in the Rockies straddling the Continental Divide, positioned on the southwestern side of a large mass of granite known as the Boulder Batholith, which dates to the Cretaceous era. In 1864, William L. Farlin founded the Asteroid Mine; the mines attracted workers from Cornwall Ireland & Wales, Canada, Austria, China, Montenegro and more. In the ethnic neighborhoods, young men formed gangs to protect their territory and socialize into adult life, including the Irish of Dublin Gulch, the Eastern Europeans of the McQueen Addition, the Italians of Meaderville. Among the migrants, many Chinese workers moved in, amongst them set up businesses that led to the creation of a Chinatown in Butte; the Chinese migrations stopped in 1882 with the passage of the Chinese Exclusion Act.
There was anti-Chinese sentiment in the 1870s and onwards due to racism on the part of the white settlers, exacerbated by economic depression, in 1895, the chamber of commerce and labor unions started a boycott of Chinese owned businesses. The business owners fought back by winning; the history of the Chinese migrants in Butte is documented in the Mai Wah Museum. The influx of miners gave Butte a reputation as a wide-open town; the city's saloon and red-light district, called the "Line" or "The Copper Block", was centered on Mercury Street, where the elegant bordellos included the famous Dumas Brothel. Behind the brothel was the famous Venus Alley, where women plied their trade in small cubicles called "cribs." The red-light district brought miners and other men from all over the region and remained open until 1982 after the closure of the Dumas Brothel. Commercial breweries first opened in Butte in the 1870s, were a large staple of the city's early economy; the breweries were always staffed by union workers.
Most ethnic groups in Butte, from Germans and Irish to Italians and various Eastern Europeans, including children, enjoyed the locally brewed lagers and other types of beer. In the late nineteenth century, copper was in great demand because of new technologies such as electric power that required the use of copper. Four industrial magnates fought for control of Butte's mining wealth; these four "Copper Kings" were William A. Clark, Marcus Daly, F. Augustus Heinze, James A. Murray; the Anaconda Copper Mining Company began in 1881 when Marcus Daly bought a small mine named the Anaconda. He was a part-owner, mine manager and engineer of the Alice, a silver mine in Walkerville, a suburb of Butte. While working in the Alice, he noticed significant quantities of high grade copper ore. Daly obtained permission to inspect nearby workings. After Daly's employers, the Walker Brothers, refused to buy the Anaconda, Daly sold his interest in the Alice and bought it himself. Daly asked San Francisco mining magnate, for additional support.
Hearst agreed to buy one-fourth of the new company's stock without visiting the site. While mining
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
Coal mining is the process of extracting coal from the ground. Coal is valued for its energy content, since the 1880s, has been used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from iron ore and for cement production. In the United Kingdom and South Africa, a coal mine and its structures are a colliery, a coal mine a pit, the above-ground structures the pit head. In Australia, "colliery" refers to an underground coal mine. In the United States, "colliery" has been used to describe a coal mine operation but nowadays the word is not used. Coal mining has had many developments over the recent years, from the early days of men tunnelling and manually extracting the coal on carts, to large open cut and long wall mines. Mining at this scale requires the use of draglines, conveyors, hydraulic jacks and shearers. Small-scale mining of surface deposits dates back thousands of years. For example, in Roman Britain, the Romans were exploiting most of the major coalfields by the late 2nd century AD.
The Industrial Revolution, which began in Britain in the 18th century and spread to continental Europe and North America, was based on the availability of coal to power steam engines. International trade expanded when coal-fed steam engines were built for the railways and steamships; until the late nineteenth century coal was mined underground using a pick and shovel, children were employed underground in dangerous conditions. Coal-cutting machines were introduced in the 1880s. By 1912, surface mining was conducted with steam shovels designed for coal mining; the most economical method of coal extraction from coal seams depends on the depth and quality of the seams, the geology and environmental factors. Coal mining processes are differentiated by whether they operate on the underground. Many coals extracted from both surface and underground mines require washing in a coal preparation plant. Technical and economic feasibility are evaluated based on the following: regional geological conditions.
Surface mining and deep underground mining are the two basic methods of mining. The choice of mining method depends on depth, density and thickness of the coal seam. Coal that occurs at depths of 180 to 300 ft are deep mined, but in some cases surface mining techniques can be used. For example, some western U. S. coal that occur at depths in excess of 200 ft are mined by the open pit methods, due to thickness of the seam 60–90 feet. Coals occurring below 300 ft are deep mined. However, there are open pit mining operations working on coal seams up to 1,000–1,500 feet below ground level, for instance Tagebau Hambach in Germany; when coal seams are near the surface, it may be economical to extract the coal using open cut mining methods. Open cast coal mining recovers a greater proportion of the coal deposit than underground methods, as more of the coal seams in the strata may be exploited; this equipment can include the following: Draglines which operate by removing the overburden, power shovels, large trucks in which transport overburden and coal, bucket wheel excavators, conveyors.
In this mining method, explosives are first used in order to break through the surface or overburden, of the mining area. The overburden is removed by draglines or by shovel and truck. Once the coal seam is exposed, it is drilled and mined in strips; the coal is loaded onto large trucks or conveyors for transport to either the coal preparation plant or directly to where it will be used. Most open cast mines in the United States extract bituminous coal. In Canada and South Africa, open cast mining is used for both thermal and metallurgical coals. In New South Wales open casting for steam coal and anthracite is practiced. Surface mining accounts for around 80 percent of production in Australia, while in the US it is used for about 67 percent of production. Globally, about 40 percent of coal production involves surface mining. Strip mining exposes coal by removing earth above each coal seam; this earth is removed in long strips. The overburden from the first strip is deposited in an area outside the planned mining area and referred to as out-of-pit dumping.
Overburden from subsequent strips are deposited in the void left from mining the coal and overburden from the previous strip. This is referred to as in-pit dumping, it is necessary to fragment the overburden by use of explosives. This is accomplished by drilling holes into the overburden, filling the holes with explosives, detonating the explosive; the overburden is removed, using large earth-moving equipment, such as draglines and trucks, excavator and trucks, or bucket-wheels and conveyors. This overburden is put into the mined strip; when all the overburden is removed, the underlying coal seam will be exposed. This block of coal may be drilled and blasted or otherwise loaded onto trucks or conveyors for transport to th
The Ruhr is a polycentric urban area in North Rhine-Westphalia, Germany. With a population density of 2,800/km2 and a population of over 5 million, it is the largest urban area in Germany and the third-largest in the European Union, it consists of several large cities bordered by the rivers Ruhr to the south, Rhine to the west, Lippe to the north. In the southwest it borders the Bergisches Land, it is considered part of the larger Rhine-Ruhr metropolitan region of more than 12 million people, among the largest in Europe. The Ruhr cities are, from west to east: Duisburg, Bottrop, Mülheim an der Ruhr, Gelsenkirchen, Herne, Dortmund and the rural districts of Wesel, Recklinghausen and Ennepe-Ruhr-Kreis; the most populous cities are Dortmund and Duisburg. In the Middle Ages, the Hellweg was an important trade route from the region of the lower Rhine to the mountains of the Teutoburg Forest; the most important towns of the region from Duisburg to the imperial city of Dortmund were concentrated along the Hellweg from the Rhineland to Westphalia.
Since the 19th century, these cities have grown together into a large complex with a vast industrial landscape, inhabited by some 7.3 million people. The Ruhr area has no administrative center. For 2010, the Ruhr region was one of the European Capitals of Culture; the urban landscape of the Ruhr extends from the Lower Rhine Basin east to the Westphalian Plain and south to the hills of the Rhenish Massif. Through the centre of the Ruhr runs a segment of the loess belt that extends across Germany from west to east; this loess belt has underlain some of Germany's richest agricultural regions. Geologically, the region is defined by coal-bearing layers from the upper Carboniferous period; the coal seams reach the surface in a strip along the river Ruhr and dip downward from the river to the north. Beneath the Lippe, the coal seams lie at a depth of 600 to 800 metres; the thickness of the coal layers ranges from one to three metres. This geological feature played a decisive role in the development of coal mining in the Ruhr.
According to the Regionalverband Ruhr, 37.6% of the region's area is built up. A total of 40.7% of the region's land remains in agricultural use. Forests account for 17.6%, bodies of water and other types of land use occupy the rest. The inclusion of four rural districts in the otherwise industrial Ruhr helps to explain the large proportion of agricultural and forested land. In addition, the city boroughs of the Ruhr region have outlying districts with a rural character. Seen on a map, the Ruhr could be considered a single city, since—at least in the north–south dimension—there are no visible breaks between the individual city boroughs, thus the Ruhr is described as a polycentric urban area, which shares a similar history of urban and economic development. Because of its history, the Ruhr is structured differently from monocentric urban regions such as Berlin and London, which developed through the rapid merger of smaller towns and villages with a growing central city. Instead, the individual city boroughs and urban districts of the Ruhr grew independently of one another during the Industrial Revolution.
The population density of the central Ruhr is about 2,100 inhabitants per square kilometre —low compared to other German cities. Between the constituent urban areas are open suburbs and some open land with agricultural fields. In some places, the borders between cities in the central Ruhr are unrecognizable due to continuous development across them. Replanting of brownfield land has created new parks and recreation areas; the Emscher Landschaftspark lies along the river Emscher virtually an open sewer, parts of which have undergone natural restoration. This park connects strips of parkland running from north to south, which were developed through regional planning in the 1920s, to form a green belt between the Ruhr cities from east to west. During the Middle Ages, much of the region, called the Ruhrgebiet was situated in the County of Mark, the Duchies of Cleves and Berg and the territories of the bishop of Münster and the archbishop of Cologne; the region included some villages and castles, was agrarian: its loess soil made it one of the richer parts of western Germany.
The free imperial city of Dortmund was the trading and cultural centre, lying on the Hellweg, an important east-west trading route, that brought prosperity to the town of Duisburg. Both towns were members of the Hanseatic League; the development of the region into an urbanized industrial area started in the late 18th century with the early industrialisation in the nearby Wupper Valley in the Bergisches Land. By around 1820, hundreds of water-powered mills were producing textiles, lumber and iron in automated processes here, and in more workshops in the hills skilled workers manufactured knives, tools and harnesses, using water and charcoal. History has no established name for this phase of the industrial revolution, but one could call it the early water-powered industrial revolution; as the machines became bigger and moved from water power to steam power, locally mined coal and charcoal became expensive and there was not enough of it. The Bergische industry ordered more coal from the new coal mining area along the Ruhr.
Impressive and expensi
In its primitive form, a wheel is a circular block of a hard and durable material at whose center has been bored a circular hole through, placed an axle bearing about which the wheel rotates when a moment is applied by gravity or torque to the wheel about its axis, thereby making together one of the six simple machines. When placed vertically under a load-bearing platform or case, the wheel turning on the horizontal axle makes it possible to transport heavy loads; the English word wheel comes from the Old English word hweol, from Proto-Germanic *hwehwlan, *hwegwlan, from Proto-Indo-European *kwekwlo-, an extended form of the root *kwel- "to revolve, move around". Cognates within Indo-European include Icelandic hjól "wheel, tyre", Greek κύκλος kúklos, Sanskrit chakra, the latter two both meaning "circle" or "wheel"; the invention of the wheel falls into the late Neolithic, may be seen in conjunction with other technological advances that gave rise to the early Bronze Age. This implies the passage of several wheel-less millennia after the invention of agriculture and of pottery, during the Aceramic Neolithic.
4500–3300 BCE: Copper Age, invention of the potter's wheel. Precursors of wheels, known as "tournettes" or "slow wheels", were known in the Middle East by the 5th millennium BCE; these were made of stone or clay and secured to the ground with a peg in the center, but required significant effort to turn. True potter's wheels were in use in Mesopotamia by 3500 BCE and as early as 4000 BCE, the oldest surviving example, found in Ur, dates to 3100 BCE; the first evidence of wheeled vehicles appears in the second half of the 4th millennium BCE, near-simultaneously in Mesopotamia, the Northern and South Caucasus, Eastern Europe, so the question of which culture invented the wheeled vehicle is still unresolved. The earliest well-dated depiction of a wheeled vehicle is on the 3500–3350 BCE Bronocice clay pot excavated in a Funnelbeaker culture settlement in southern Poland. In nearby Olszanica 5000 BCE 2.2 m wide door were constructed for wagon entry. This barn was 40 m long with 3 doors; the oldest securely dated real wheel-axle combination, that from Stare Gmajne near Ljubljana in Slovenia is now dated within two standard deviations to 3340–3030 BCE, the axle to 3360–3045 BCE.
Two types of early Neolithic European wheel and axle are known. They both are dated to c. 3200–3000 BCE. In China, the wheel was present with the adoption of the chariot in c. 1200 BCE, although Barbieri-Low argues for earlier Chinese wheeled vehicles, c. 2000 BCE. In Britain, a large wooden wheel, measuring about 1 m in diameter, was uncovered at the Must Farm site in East Anglia in 2016; the specimen, dating from 1,100–800 BCE, represents the most complete and earliest of its type found in Britain. The wheel's hub is present. A horse's spine found; the wheel was found in a settlement built on stilts over wetland, indicating that the settlement had some sort of link to dry land. Although large-scale use of wheels did not occur in the Americas prior to European contact, numerous small wheeled artifacts, identified as children's toys, have been found in Mexican archeological sites, some dating to about 1500 BCE, it is thought that the primary obstacle to large-scale development of the wheel in the Americas was the absence of domesticated large animals which could be used to pull wheeled carriages.
The closest relative of cattle present in Americas in pre-Columbian times, the American Bison, is difficult to domesticate and was never domesticated by Native Americans. The only large animal, domesticated in the Western hemisphere, the llama, a pack animal but not physically suited to use as a draft animal to pull wheeled vehicles, did not spread far beyond the Andes by the time of the arrival of Columbus. Nubians from after about 400 BCE used wheels as water wheels, it is thought. It is known that Nubians used horse-drawn chariots imported from Egypt; the wheel was used, with the exception of the Horn of Africa, in Sub-Saharan Africa well into the 19th century but this changed with the arrival of the Europeans. Early wheels were simple wooden disks with a hole for the axle; some of the earliest wheels were made from horizontal slices of tree trunks
Copper is a chemical element with symbol Cu and atomic number 29. It is a soft and ductile metal with high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is used as a conductor of heat and electricity, as a building material, as a constituent of various metal alloys, such as sterling silver used in jewelry, cupronickel used to make marine hardware and coins, constantan used in strain gauges and thermocouples for temperature measurement. Copper is one of the few metals; this led to early human use in several regions, from c. 8000 BC. Thousands of years it was the first metal to be smelted from sulfide ores, c. 5000 BC, the first metal to be cast into a shape in a mold, c. 4000 BC and the first metal to be purposefully alloyed with another metal, tin, to create bronze, c. 3500 BC. In the Roman era, copper was principally mined on Cyprus, the origin of the name of the metal, from aes сyprium corrupted to сuprum, from which the words derived and copper, first used around 1530.
The encountered compounds are copper salts, which impart blue or green colors to such minerals as azurite and turquoise, have been used and as pigments. Copper used in buildings for roofing, oxidizes to form a green verdigris. Copper is sometimes used in decorative art, both in its elemental metal form and in compounds as pigments. Copper compounds are used as bacteriostatic agents and wood preservatives. Copper is essential to all living organisms as a trace dietary mineral because it is a key constituent of the respiratory enzyme complex cytochrome c oxidase. In molluscs and crustaceans, copper is a constituent of the blood pigment hemocyanin, replaced by the iron-complexed hemoglobin in fish and other vertebrates. In humans, copper is found in the liver and bone; the adult body contains between 2.1 mg of copper per kilogram of body weight. Copper and gold are in group 11 of the periodic table; the filled d-shells in these elements contribute little to interatomic interactions, which are dominated by the s-electrons through metallic bonds.
Unlike metals with incomplete d-shells, metallic bonds in copper are lacking a covalent character and are weak. This observation explains the low high ductility of single crystals of copper. At the macroscopic scale, introduction of extended defects to the crystal lattice, such as grain boundaries, hinders flow of the material under applied stress, thereby increasing its hardness. For this reason, copper is supplied in a fine-grained polycrystalline form, which has greater strength than monocrystalline forms; the softness of copper explains its high electrical conductivity and high thermal conductivity, second highest among pure metals at room temperature. This is because the resistivity to electron transport in metals at room temperature originates from scattering of electrons on thermal vibrations of the lattice, which are weak in a soft metal; the maximum permissible current density of copper in open air is 3.1×106 A/m2 of cross-sectional area, above which it begins to heat excessively. Copper is one of a few metallic elements with a natural color other than silver.
Pure copper acquires a reddish tarnish when exposed to air. The characteristic color of copper results from the electronic transitions between the filled 3d and half-empty 4s atomic shells – the energy difference between these shells corresponds to orange light; as with other metals, if copper is put in contact with another metal, galvanic corrosion will occur. Copper does not react with water, but it does react with atmospheric oxygen to form a layer of brown-black copper oxide which, unlike the rust that forms on iron in moist air, protects the underlying metal from further corrosion. A green layer of verdigris can be seen on old copper structures, such as the roofing of many older buildings and the Statue of Liberty. Copper tarnishes when exposed to some sulfur compounds, with which it reacts to form various copper sulfides. There are 29 isotopes of copper. 63Cu and 65Cu are stable, with 63Cu comprising 69% of occurring copper. The other isotopes are radioactive, with the most stable being 67Cu with a half-life of 61.83 hours.
Seven metastable isotopes have been characterized. Isotopes with a mass number above 64 decay by β−, whereas those with a mass number below 64 decay by β+. 64Cu, which has a half-life of 12.7 hours, decays both ways.62Cu and 64Cu have significant applications. 62Cu is used in 62Cu-PTSM as a radioactive tracer for positron emission tomography. Copper is produced in massive stars and is present in the Earth's crust in a proportion of about 50 parts per million. In nature, copper occurs in a variety of minerals, including native copper, copper sulfides such as chalcopyrite, digenite and chalcocite, copper sulfosalts such as tetrahedite-tennantite, enargite, copper carbonates such as azurite and malachite, as copper or copper oxides such as cuprite and tenorite, respectively; the largest mass of elemental copper discovered weighed 420 tonnes and was found in 1857 on the Keweenaw Peninsula in Michigan, US. Native copper is a polycrystal
This article is about pouring concrete in moving forms. See Slipform stonemasonry for another type of slip forming, Slipcasting for manufacture of ceramic vessels. Slip forming, continuous poured, continuously formed, or slipform construction is a construction method in which concrete is poured into a continuously moving form. Slip forming is used for tall structures, as well as horizontal structures, such as roadways. Slipforming enables continuous, non-interrupted, cast-in-place "flawless" concrete structures which have superior performance characteristics to piecewise construction using discrete form elements. Slip forming relies on the quick-setting properties of concrete, requires a balance between quick-setting capacity and workability. Concrete needs to be workable enough to be placed into the form and consolidated, yet quick-setting enough to emerge from the form with strength; this strength is needed because the freshly set concrete must not only permit the form to "slip" by the concrete without disturbing it, but support the pressure of the new concrete as well as resist collapse caused by the vibration of the compaction machinery.
[[File:Gleitschalung slipform ´Bitschnau Gleit & Schalungstechnik.jpg|thumb|right|Slipforming Grain silo in Zürich for In vertical slip forming the concrete form may be surrounded by a platform on which workers stand, placing steel reinforcing rods into the concrete and ensuring a smooth pour. Together, the concrete form and working platform are raised by means of hydraulic jacks; the slipform rises at a rate which permits the concrete to harden by the time it emerges from the bottom of the form. In horizontal slip forming for pavement and traffic separation walls concrete is laid down, vibrated and settled in place while the form itself moves ahead; this method was devised and utilized in Interstate Highway construction initiated by the Eisenhower administration during the 1950s. The slip forming technique was in use by the early 20th century for building silos and grain elevators. James MacDonald, of MacDonald Engineering of Chicago was the pioneer in utilizing slip form concrete for construction.
His concept of placing circular bins in clusters was patented, with photographs and illustrations, contained in a 1907 book, “The Design Of Walls, And Grain Elevators”. In 1910, MacDonald published a paper “Moving Forms for Reinforced Concrete Storage Bins,” describing the use of molds for moving forms, using jacks and concrete to form a continuous structure without joints or seams; this paper details the procedure for creating slip form concrete structures. On May 24, 1917, a patent was issued to James MacDonald of Chicago, "for a device to move and elevate a concrete form in a vertical plane". James MacDonald’s bin and silo design was utilized around the world into the late 1970s by MacDonald Engineering. In the 1947-1950 period, MacDonald Engineering constructed over 40 concrete towers using the slip-form method for AT&T Long Lines up to 191 ft tall for microwave relay stations across the United States; the former LandMark Hotel/Casino in Las Vegas was constructed in 1961 by MacDonald Engineering as a subcontractor, utilizing Macdonald’s concept of slip form concrete construction to build the 31 story reinforced steel tower.
The technique was introduced to commercial buildings in the late 1960s. One of Its first uses in high-rise buildings in the United States was on the shear wall supported apartment building at Turk & Eddy Streets in San Francisco, CA, in 1962, built by the San Francisco office of Macdonald Engineering; the first notable use of the method in a residential/retail business was the Skylon Tower in Niagara Falls, completed in 1965. Another unusual structure was the tapered buttress structures for the Sheraton Waikiki Hotel in Honolulu, Hawaii, in 1969. Another shear wall supported structure was the Casa Del Mar Condominium on Key Biscayne, Miami, FL in 1970. From the 1950s, the vertical technique was adapted to mining head frames, ventilation structures, below grade shaft lining, coal train loading silos, it is used for structures which would otherwise not be possible, such as the separate legs of the Troll A deep sea oil drilling platform which stands on the sea floor in water about 1000 feet deep, has an overall height of 472 meters, weighs 656,000 tons, has the distinction of being the tallest structure moved by mankind.
In addition to the typical silos and shear walls and cores in buildings, the system is used for lining underground shafts and surge tanks in hydroelectric generating facilities. The technique was utilized to build the Inco Superstack in Sudbury and the CN Tower in Toronto. In 2010, the technique was used to build the core of the supertall Shard London Bridge tower in London, England. Slip-Form Construction Time Lapse - The Dalles, Oregon Retrieved 2014-04-22. Slipform MacDonald Engineering's slip form concrete grain silos Nawy, Edward G. Concrete Construction Engineering Handbook. New York: CRC Press, 2008