The most important use of cement is the production of mortar and concrete – the bonding of natural or artificial aggregates to form a strong building material which is durable in the face of normal environmental effects.

Cement should not be confused with concrete as the term cement explicitly refers to the dry powder substance. Upon the addition of water and/or additives the cement mixture is referred to as concrete, especially if aggregates have been added.

Cement is made by heating limestone with small quantities of other materials (such as clay) to 1450°C in a kiln, in a process known as calcination. The resulting hard substance, called ‘clinker’, is then ground with a small amount of gypsum into a powder to make ‘Ordinary Portland Cement’, the most commonly used type of cement (often referred to as OPC).

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As defined by the European Standard EN197.1, "Portland cement clinker is a hydraulic material which shall consist of at least two-thirds by mass of calcium silicates (3CaO.SiO2 and 2CaO.SiO2), the remainder consisting of aluminium- and iron-containing clinker phases and other compounds. The ratio of CaO to SiO2 shall not be less than 2.0. The magnesium content (MgO) shall not exceed 5.0% by mass." (The last two requirements were already set out in the German Standard, issued in 1909).

Portland cement clinker is made by heating, in a kiln, a homogeneous mixture of raw materials to a sintering temperature, which is about 1450 °C for modern cements. The aluminium oxide and iron oxide are present as a flux and contribute little to the strength. For special cements, such as Low Heat (LH) and Sulfate Resistant (SR) types, it is necessary to limit the amount of tricalcium aluminate (3CaO.Al2O3) formed.

The major raw material for the clinker-making is usually limestone (CaCO3) mixed with a second material containing clay as source of alumino-silicate. Normally, an impure limestone which contains clay or SiO2 is used. The CaCO3 content of these limestones can be as low as 80%. Second raw materials (materials in the rawmix other than limestone) depend on the purity of the limestone. Some of the second raw materials used are: clay, shale, sand, iron ore, bauxite, fly ash and slag. When a cement kiln is fired by coal, the ash of the coal acts as a secondary raw material.

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Natural cement is produced in a simple process that begins with the calcination of crushed carbonate sedimentary rocks in kilns. The resulting clinker is ground into a fine powder before being shipped to market. Historically, this natural cement product was packaged in paper-lined wooden barrels or heavy canvas bags.

Rosendale natural cement was produced from dolostone extracted from the Rosendale and Whiteport members of the Late Silurian Rondout Formation. The natural levels of magnesium and clay in the dolostone from the Rondout Formation are ideally suited for cement production and required none of the chemical additives characteristic of modern Portland cement production.

Many of the original cement plants in the Rosendale area are preserved in the Snyder Estate Natural Cement Historic District.

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The objective of kiln operation is to make clinker with the required chemical and physical properties, at the maximum rate that the size of kiln will allow, while meeting environmental standards, at the lowest possible operating cost. The kiln is very sensitive to control strategies, and a poorly run kiln can easily double cement plant operating costs.

Portland cement clinker was first made (in 1842) in a modified form of the traditional static lime kiln. The basic, egg-cup shaped lime kiln was provided with a conical or beehive shaped extension to increase draught and thus obtain the higher temperature needed to make cement clinker. For nearly half a century, this design, and minor modifications, remained the only method of manufacture.

A kiln is basically an industrial oven, and although the term is generic, several quite distinctive designs have been used over the years. Although perhaps more normally associated with pottery making, both ‘Bottle’ and their very close relatives ‘Beehive’ kilns, were also the central feature of any cement works. Early designs tended to be updraft kilns, which were often built as a straight sided cone into which the flame was introduced at, or below, floor level.

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The method of making cement from limestone and low-silica bauxite was patented in France in 1908 by Bied of the Pavin de Lafarge Company. The initial development was as a result of the search for a cement offering sulfate resistance. The cement was called "Ciment Fondu". Subsequently, its other special properties were discovered, and these guaranteed its future in niche applications.

The main active constituent of calcium aluminate cements is monocalcium aluminate (CaAl2O4). It usually contains other calcium aluminates as well as a number of less reactive phases deriving from impurities in the raw materials. Rather a wide range of compositions is encountered, depending on the application and the purity of aluminium source used.

The cement is made by fusing together a mixture of a calcium-bearing material (normally limestone) and an aluminium-bearing material (normally bauxite for general purposes, or refined alumina for white and refractory cements). The liquified mixture cools to a basalt-like clinker which is ground alone to produce the finished product. Because complete melting usually takes place, raw materials in lump-form can be used.

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Saltconcrete was used for the first time in 1984 in the Kali mine in Rocanville in Canada.[2] A salt-concrete seal was also installed in the Asse II mine in Lower Saxony in 1995.

Since the end of the repository for radioactive waste Morsleben in 1998, the salt dome stability deteriorated to a state where it could collapse. Since 2003, a volume of 480.000 m3 of saltconcrete has been pumped into the pit to temporarily stabilize the upper levels. In addition another 4.000.000 m3 of saltconcrete will be used to temporarily stabilize the lower levels.

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This process grows cement-like engineering structures and marine ecosystems, often for mariculture of corals, oysters, clams, lobsters and fish in salt water. It works by passing a small electrical current through electrodes in the water. Biorock grows more or less without limit as long as current flows.

Biorock accelerates coral growth by as much as five-fold and increases coral survival. Biorock can enable coral growth and regrowth even in the presence of environmental stress, such as warming water temperatures. When mixed with aggregates, it can build components on the sea bottom or on land. Biorock represents the only known method that can sustain and grow natural coral species using only basic conducting elements, typically of a common metal such as steel.

Applying a low voltage electrical current (completely safe for swimmers and marine life) to a submerged conductive structure causes dissolved minerals in seawater to precipitate and adhere to that structure. The result is a composite of limestone and brucite with mechanical strength similar to concrete. Derived from seawater, this material is similar to the composition of natural coral reefs and tropical sand beaches.

Biorock structures can be built in any size or shape depending only on the physical makeup of the sea bottom, wave, current energies and construction materials. They are well suited for remote, third world sites where exotic building materials, construction equipment and highly skilled labor are non-existent.

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Fibre cement is a composite material made of sand, cement and cellulose fibers. In appearance fibre cement cladding most often consists of overlapping horizontal boards, imitating wooden cladding, clapboard and imitation shingles. Fiber cement siding is also manufactured in a sheet form and is used not only as cladding but is also commonly used as a soffit / eave lining and as a tile underlay on decks and in bathrooms.

Fiber cement cladding is not only used as an exterior cladding, it can also be utilised as a substitute for timber fascias and barge boards in high fire areas. Fibre cement cladding is a very heavy product and requires two people to carry the uncut sheets. Thin fibre cement cladding is fragile before installation and must be handled carefully; it is prone to chipping and breakage if improperly handled.

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