Cement - SpeedyLook encyclopedia

History

Cements would initially have been invented by the Égyptiens then improved by following civilizations by the use of Chaux. The Greek of Italy reinforced it with pozzolanic ashes , use taken again and generalized by the Romains. Until the modern Time, cement is flexible, often a lime, added with additive like the Tuile S or crushed bricks whose clay has hydraulic properties. Pozzolana (volcanic ground of Pouzzoles, area of Naples, Italy) is very much used as additive. Cement takes its contemporary meaning only at the 19th century, when Louis Vicat identifies the phenomenon of hydraulicity of limes in 1817 and that of cements (which it called eminently hydraulic limes or limiting limes) in 1840.

Research on the hydraulicity of limes starts at the end of the 18th century century to lead about 1840 with the manufacture of modern cements. It related to the fat limes, nonhydraulic which do not take under water, the hydraulic limes which take even under water, eminently hydraulic limes (clay rich person) which take very quickly and limiting limes (too much rich in clays) which take very quickly then break up (if they are not cooked with the degree of pasty fusion).

In 1796, James Parker discovers on the Island of Sheppey, the United Kingdom, the quick-setting cement (an eminently hydraulic lime or natural cement with rapid hardening, cooked with 900°C as ordinary natural limes) which it baptizes commercially Roman cement. This cement obtains thereafter, of 1820 to approximately 1920, a great reputation. It is manufactured in all Europe and is used to make mouldings with the gauge or to manufacture factitious moulded cement stones. At the beginning of the 19th century century, all Europe activates itself, France especially, nothing to have to the British nor with Italian pozzolana. And the French Louis Vicat discovers in 1817 the principle of hydraulicity of limes - concerning the proportion of clay and the temperature of cooking - and publishes his work without taking patent. In 1824, the British Joseph Aspdin deposits a patent for the manufacture of a hydraulic lime with rapid hardening which it commercially calls Portland cement (because the color of its product resembles the famous stones of the careers of the peninsula of “Portland” located in Handle. It is cement similar to those which Vicat still describes that its patent is vague. But 1840 should be waited until, and the discovery of the principles of hydraulicity of slow cements (known as today Portland cements) always by Louis Vicat (Société Vicat) - a cooking at the pasty melting point is 1450°C which makes it possible to obtain the clinker - to see a real manufacture of these modern cements and to then appear a concrete architecture cased then reinforced concrete.

Manufacture of cement running, or Portland cement

The manufacture of cement is distinguished in five major stages:

the extraction
the prehomogeneisation
drying and crushing
cooking
crushing

Extraction

The extraction consists in extracting the virgin raw materials (like limestone and clay) starting from natural careers with open sky. These raw materials are extracted from the rock faces by demolition with the explosive or the mechanical shovel. The rock is conveyed by dumpers and/or conveying belts towards a workshop of crushing. The raw materials must be sampled, proportioned and mixed in order to obtain a regular composition in time. The sampling uninterrupted makes it possible to determine the quantity of the various additions necessary (alumina, iron oxide and silica).

Préhomogénéisation

The phase of prehomogeneisation consists in creating in a hall a prehomogene mixture by laying out the matter in superimposed horizontal layers, then by vertically taking it again using a bucket-wheel.

Principles and manufacturing methods

The manufacture of cement is reduced schematically to the three following operations:

preparation of the vintage
cooking
crushing and conditioning

There exist 4 methods of manufacture of cement which depend primarily on material:

Manufacture of cement by wet process (oldest).
Manufacture of cement by semi-wet way (on the basis of the wet process).
Manufacture of cement by dry roads (the most used).
Manufacture of cement by way sowing (on the basis of the dry roads).

The basic composition of current cements is a mixture of silicates and calcium aluminates resulting from the combination of lime (CAD) with silica (SiO2), alumina (Al2O3), and iron oxide (Fe2O3). Lime necessary is brought by rocks limestones, alumina, the silica and oxide iron by clays. The materials are in nature in the form of limestone, clay or marl and contain, in addition to oxides already mentioned, other oxides and in particular Fe2O3, the ferric oxide.

The principle of the manufacture of cement is the following: limestones and clays are extracted from the careers, then crushed, homogenized, carried at high temperature (1450°C) in a furnace. The product obtained after fast cooling (hardening) is the clinker.

A mixture of clay and limestone is heated. At the beginning, one causes the departure of the water of damping, then beyond 100°C, the departure of more dependant water. Starting from 500°C the decomposition of calcium carbonate starts (CaCO) contained in lime and carbonic gas (CO) limestone (CAD).

The mixture is carried to 1450-1550°C, melting point. The liquid thus obtained allows obtaining the various reactions. It is supposed that the components of cement are formed in the following way: part of CAD is retained by Al2O3 and Fe2O3 by forming a liquid phase. SiO and the remaining CAD react to give the silicate bicalcic of which a part is transformed into tricalcic silicate insofar as there remains still CAD not combined. These are the silicates which give the main part of resistances in cement.

Manufacture by wet process

This way is used for a long time. It is the oldest process, simplest but which requires the most energy.

In this process, limestone and clay are mixed and crushed finely with water in order to constitute a rather liquid paste (28 to water 42%). One vigorously brews this paste in large basins from 8 to 10 m in diameter, in which a horse-gear of harrows turns.

The paste is then stored in large basins of several thousands of cubic meters, where it is continuously mixed and thus homogenized. This mixture is called the vintage. Chemical analyzes make it possible to control the composition of this paste, and to make the corrections necessary before its cooking.

The paste is then sent to the entry of a revolving furnace, heated at its end by an interior flame. A slightly tilted revolving kiln consists of a steel cylinder of which the length can reach 200 meters. One distinguishes with interior from the furnace several zones, whose 3 principal zones are:

Zone of drying.
Zone of decarbonation.
Zone of clinkerisation.

The walls of the upper part of the furnace (zone of drying - approximately 20% length of the furnace) are furnished with marine chains in order to increase the heating exchanges between the hot paste and parts of the furnace.

The clinker on the outlet side of the furnace, passes in coolers (hardening of the clinker) of which there exist several types (grid cooler, with small baloons). The speed of hardening has an influence on the properties of the clinker (vitreous phase).

In any case, whatever the manufacturing method, on the outlet side of the furnace, one has the same clinker which is still hot of approximately 600-1200°C. It is necessary to crush this one very finely and very regularly with approximately 5% CaSO gypsum in order to “regularize” the catch.

Crushing is a delicate and expensive operation, not only because the clinker is a hard material, but also because even the best crushers have deplorable energetic efficiencies.

The ball mills are large cylinders laid out almost horizontally, filled with half of steel balls and that one makes quickly turn around their axis (20t/mn) and cement reaches an high temperature (160°C), which requires watering external of the crushers. One introduces the clinker with a certain percentage of gypsum partly high and one recovers the partly low powder.

In crushing with open circuit, the clinker passes only once in crushing. In crushing in closed circuit, the clinker passes quickly in the crusher then to the exit, is sorted in a cyclone. The purpose of crushing is, on the one hand to reduce the grains of the powder clinker, on the other hand to proceed to the addition of the gypsum (approximately 4%) to control some properties of Portland cement (the time of catch and hardening).

On the outlet side of the crusher, cement has a temperature approximately of 160 °C and before being transported towards storage bins, it must pass to the cooler to centrifugal force so that the temperature of cement remains with approximately 65 °C.

Manufacture by dry roads

Usual cements are manufactured starting from a mixture of limestone (CaCO) approximately of 80% and clay (SiO-Hello) approximately of 20%. According to the origin of the raw materials, this mixture can be corrected by contribution of bauxite, iron oxide or other materials providing the necessary silica and alumina complement.

After being finely crushed, the powder is transported since the homogenizing silo to the furnace, either by pump, or by hovercraft.

The furnaces consist of two parts:

A fixed vertical furnace, preheater (exchanging cyclones of heat). A revolving kiln. The gases heat the raw meal which circulates in the cyclones in opposite direction, by gravity. The powder warms up thus up to 800 °C approximately and thus loses its carbonic gas (CO) and its water. The powder penetrates then in a revolving kiln similar to that used in the wet process, but much shorter.

The method of manufacture per dry roads presents to the manufacturers technical big problems:

The possible segregation between clay and limestone in the preheaters. Indeed, the system used seems to be harmful and makes some, is used elsewhere, for sorting particles. In the case of the manufacture of cements, it of it is nothing. The powder remains homogeneous and this can be explained by the fact why clay and limestone have the same density (2,70 g/cm ³). Moreover, the material was designed in this spirit and all the precautions were taken. The problem of dust. This problem is made all the more acute, that the public authorities, very sensitized by the problems of harmful effect, impose Draconian conditions. This obliges the manufacturers to install dust extractors, which increases the investments of the cement factory considerably. The dust extractors consist of metal wire grids carried with high voltage and on which come to set grains of ionized dust. These grains of dust agglomerate and under the action of vibrators which agitate the wire fall down at the bottom of the dust extractor where they are recovered and returned in the furnace. Apart from the breakdowns, these apparatuses have outputs of about 99%, but absorb a big part of the capital of equipment of the cement factory. The problem of the homogeneity of the vintage is delicate. We saw how it could be solved by means of a prehomogeneisation then of a homogenization.

Drying and crushing

Drying and crushing are the stage aiming at supporting the later chemical reactions. The raw materials are dried and crushed very finely (about the micron) in ball mills (or more recently, in vertical grinding stone crushers, plus energy savers).

One distinguishes three principal types from " voies" according to the type of preparation:

the wet process: it is the oldest technique. It is also greediest in energy, necessary to the evaporation of the water surplus.

In the two following techniques, the raw materials are perfectly homogenized and dried in the form of “ believed ” or “ flour ”.

dry roads: the flour is introduced directly into the furnace in powder form, after a pre-heating in a tower with heat exchangers.

the way sowing: before introduction into the furnace, the flour is transformed into “granules” by humidification in great tilted rotary “plates”.

The vintage is then introduced into a long furnace (60m with 200m) rotary (1.5 to 3 turns per minute) tubular (until 6m of diameter), slightly tilted (2 to 3% of slope)

Cooking

The vintage will follow various stages of transformation at the time of its slow progression in the furnace towards the low part to the meeting of the flame. This source of heat is fed with crushed coal, heavy fuel, gas, or partly with fuels of substitution coming from other industries, such as the petroleum coke, the tires worn, the animal flours, waste oils.

The temperature necessary to the Clinkerisation is about 1 450°C. The power consumption is between 3 200 and 4 200 K Joules per ton of Clinker, which is the finished semi product obtained at the end of the cycle of cooking. It is presented in the form of gray granules.

On the outlet side of the furnace, a grid cooler makes it possible to ensure the hardening of the incandescent nodules and to bring back them to a temperature approximately 100°C.

The clinker is the result of a whole of progressive physicochemical reactions (clinkerisation) allowing:

the decarbonation of calcium carbonate (giving the quicklime)
the scission of clay out of silica and alumina
combination of silica and alumina with lime to form silicates and aluminates of lime.

Crushing

The clinker is then finely crushed to give cement to the active hydraulic properties. This crushing is carried out in ball mills, devices cylindrical charged with steel balls and put in rotation.

At the time of this stage, the Gypsum (3 to 5%), essential to the regulation of catch of cement, is added to the clinker. One obtains then cement Portland .

The cements with additions are obtained by the addition at the time of the phase of crushing of additional biogenic salts contained in materials such as:

the slag of blast furnaces (residues of the Iron and steel industry)
fly-ashes of powerplants
the fillers limestones (aggregates)
natural or artificial pozzolanas

Chemistry of the cement

Phases cimentières

To indicate the phases cimentières, one uses shortened a notation in general known as “Shorthand notation”: C for CAD (Lime), S for SiO₂ (Silica), has for Al₂O₃ (Alumine) and F for Fe₂O₃ (Hématite). The phases usually met in the industry of cement are:

Confines to bed C3S: (CAD) ₃ (SiO₂);
Aluminate C3A: (CAD) ₃ (Al₂O₃);
Bellite C2S: (CAD) ₂ (SiO₂);
Calcareous ( limestone ): CaCO₃
Cellulose acetate C4AF: cf ferrite. Célite name is not current any more;
free Lime ( free file ): CAD, the content must be in general lower than 2% in mass in the clinker (the quantity of free lime increases when the temperature of the furnace drops);
Ferrite or Aluminoferrite or Brownmillerite C4AF: (CAD) ₄ (Al₂O₃) (Fe₂O₃), one sees sometimes half-formula (CAD) ₂FeAlO₃;
Gypsum: CaSO₄.2 (H₂O); heated between 60 °C and 200 °C, the gypsum is dehydrated and given the Plâtre;
Periclase: MgO;
Portlandite : Hydroxide of Calcium Ca (OH) ₂, coming from the hydration of free lime.
Sand, Silica: SiO₂

The chemical composition in the long term guarantees qualities of cement, i.e. not only during manufacture, but also of the months, even of the years after marketing. Analyzes are thus carried out on samples taken regularly throughout the manufactoring process. One also analyzes the raw materials and fuels in order to know their content of various compounds and of thus being able to proportion them. These analyzes became all the more important as the manufacture of cement has more and more recourse to products of recycling, so much in the raw materials (for example the slag) that for the fuels (waste not releasing from toxic smoke, animal flours…). In addition, this analysis also allows a retroactive piloting of the furnace: when the free lime rate (CAD) is too important, that means that the furnace is not hot enough.

Final quality is evaluated by modules, i.e. computed values starting from the composition. One defines for example:

Module of saturation of Kühl: $LSI = \ frac {\ mathrm {CAD}} {\ mathrm {2,8 \ cdot SiO_ {2} + 1,1 \ cdot Al_ {2} O_ {3} + 0,7 \ cdot Fe_ {2} silicic O_ {3}}}$
Module (ms or SR): $MS= \ frac {\ mathrm {SiO_ {2}}} {\ mathrm {Al_ {2} O_ {3} + Fe_ {2} O_ {3}}}$
Module alumino-ferrous ore (AF or AR): $AF= \ frac {\ mathrm {Al_ {2} O_ {3}}} {\ mathrm {Fe_ {2} O_ {3}}}$

Contamination

The presence of Chlorine (Chloride S) and of sulfur (Sulfate S, Sulfide) in the raw materials is problematic. Indeed, while heating, chlorine and sulfur volitilize and react with the compounds Alcalin S to form alkaline chlorides and sulfides.

Tests Laboratory

Physical measurements

to supplement

specific Surface : The smoothness of crushing of cement is expressed in terms of surface specific (cm ² /g) and measured by the test of Blaine, said permeability to the air, using the relation of Arcy-Kozeny which establishes that the crossing of a bed of granules by a fluid is affected by the specific surface of the granules. Thus, by calculating the duration that puts a gas under pressure to cross a given volume of granules, one from of deduced surface from the granules. The finer crushing is, and the more important calculated surface is. This experiment occurring in a determined volume, one can imagine to obtain an infinite surface developed by crushing always more finely cement. It is an industrial use of a model explained by mathematics Fractale S (a dimension of order N finished, including a dimension of a nature n-1 tending towards the infinite one).

Chemical measurements

to supplement

Various cements

Cements can be classified in five principal big families and 27 alternatives (see the standard EN-197-1-2000) for more details:

Portland cement (noted CEM I)
Portland cement made up (noted CEM II)
Cements of blast furnaces (noted CEM III)
Pozzolanic cements (noted CEM IV)
Slag cements and with ashes or made up cement (noted CEM V)

Economy of cement

an heavy industry…

The installation necessary to the production of a million tons of cement is about 150 million euros and the cost of a factory is equivalent to 3 years of sales turnover.

… strongly consuming energy…

Each ton of cement produced requires the equivalent from 60 to 130 kg of fuel (or its equivalent) and an average of 110 kWh.

… with weak manpower need…

A modern factory of a million tons of cement employs less than 150 people.

… manufacturing a weighty product…

The transport costs by road become equivalent to the cost of the product beyond 300 km (25 T of payload per truck) and limit thus the operating range of the terrestrial routing. This constraint makes market of cement a regional market. Nevertheless, the lower costs of the ocean freight taking into consideration transported volume (boats of 35.000 tons) allow the intercontinental exchanges (brought back to the transported ton, it is less expensive to make cross the Atlantic to a cement cargo than to move it of 300 km per road way).

… with the homogeneous characteristics…

Although cement is produced starting from local natural materials, different from one factory to another, the end product answers the same standards. So more than quality of cement, it is its availability and the customer service who are determining in the sale contract, after of course the selling price.

… with consumption strongly related to the level of local development.

In Europe and North America, the market demand for cement strongly increased during the 20th century, according to the development of the industry and the needs for the increasing urbanization. After the Second world war, and in spite of a cyclic evolution, the consumption of the industrialized countries was multiplied by a factor 6 to 8, until the oil crisis of 1975. Since then the Western markets known as mature decreased about 20 to 40%, the requirements in heavy infrastructures having been satisfied and replaced by consumption for maintenance.

Nevertheless, during the 25 last years, certain European countries (Greece, Portugal, Spain and Turkey for example) doubled, even triplet their consumption in relation to their strong growth rate interns (GDP)

From one country to another, the cement consumption per capita strongly varies according to the geographical profiles (tunnels and bridges in the mountainous areas), of the seismic constraints (Greece, Turkey) and atmospheric (concrete highways in the countries of north), of the local practices, the population densities and the cycle of growth. The European average was in 2004 (source Cembureau) of 528 kg per capita, with peaks to 1221 kg for Luxembourg, 1166 kg for Spain and 963 kg for Greece and of low for Sweden (192 kg), Latvia (200 kg) and the United Kingdom (216 kg).

Production companies

The worldwide production of cement is dominated by some Western international groups (classification at the end of 2005):

world Lafarge, France, n°1
Holcim, Switzerland, n°2 world
Cemex, world Mexico, n°3
HeidelbergCement, Germany, n° 4 world
Italcementi, Italy, n°5 world

in France: Group French Ciments of which: Calcia cements: Official site: Cements Calcia

But there also exists of many independent producers, for example

France

Vicat

Algérie:

ERCE-GIC - Official site:

International agencies and standards

The first result of harmonization of cements appeared in 2000, developed by CEN (“European Committee for Standardization) (www.cenorm.be). Cement is then the first product standardized (EN-197-1-2000) in agreement with the CPD (Construction Products Directive). The standard defines 27 common cements and their components, including recommendations of use (proportions of the mixtures), as well as mechanical specificities, physical and chemical of various cements and their components. The 27 classes are divided into 5 groups, according to the components other than the clinker. Since April 2003, all cements received label EC, in agreement with the EN standard 197-1.

The tests to be practiced on cements throughout the line production, to measure their properties, were described in a European pre-standard finalized in 1989 (IN 196 series).

CEN also leans on standardization the 6 other types of following cements:

Cements with low heat of hydration
quick-setting Cements with low resistance
Flexible hydraulics truck drivers
Cements calcio-aluminates
sulphato-resistant Cements

The C01 committee of ASTM is dedicated to hydraulic cements.

The following standards apply to the field of cements:

IN 196.2: chemical Analysis by Complexometry

Glossary of cements

; Aluminous cement The aluminous cement was invented by J. Bied, scientific director of Cements Lafarge, in 1908 and was industrially manufactured in France starting from 1918. It is cement containing calcium aluminates. Portland cements them contain calcium silicates. These aluminates do not release from lime during hydration and offer several special properties to the concrete or the aluminous mortar:

a rapid hardening
a high chemical resistance
a resistance raised to wear
a strength to the high temperatures
a concrete accelerator in cold weather

; Artificial cement Artificial cement, or Portland cement, is a mixture artificial (of the hand of the man) from 76 to 80% of carbonate of lime, and 24 to clay 20%, crushed and mixed with vintage, then cooked at a temperature of 1 450 °C to obtain a very hard artificial rock, the clinker, crushed again very finely, gives artificial cement.

It is cement slow, manufactured in great quantity starting from 1850 approximately, used today for the current concretes and reinforced concretes, like for work of high-tech like those of the Highways Departments or the works of Article Its long and complicated manufacture returned it expensive a long time. He was imitated with less expenses by than one can call the “artificial forgeries” (see this term).

In 1897, the Commission of testing method of materials classified in the same category all the slow-setting cements, and starting from 1902, the Commission of limes and cements, does not use any more this term of artificial and includes it in Portland cements.

; White cement or extra-white The white cement or extra-white is a Portland cement without metallic oxide (kind of heavy lime), intended for the manufacture of the squares or the mouldings. It is remarkable by its smoothness and its whiteness, not producing any gerçure on smooth surface. He was invented in 1870. Its catch is done between 6 and 15 hours.

; Cement flaring (or clinker) Clinker, cooked with 1 450 °C and not yet ground, can be used as cement, one speaks then about cement flaring. It is very hard. Its catch is much slower than moderately cooked cements with 1 000 °C, but it presents a hardening and a completely extraordinary degree of cohesion.

Crushed and mixed with gypsum to delay the catch of it, it is at the base of the current manufacture of modern ordinary cements (Portland cement). At the 19th Dauphine century in , the moderately cooked pieces, often of yellow color, was called yellow calcinings or barks. The pieces lime were called black calcinings. The word clinker, imported of the United Kingdom, was especially used to indicate black calcinings of artificial Portland cement.

; Cement with ashes Cements with ashes were manufactured for the first time in France in 1951, by P. Fouilloux.

; Molten cement Cement of the beginning of the 20th century century, very aluminous, from normal catch, of which hardening requires much water, releases much heat and is very fast. It is indecomposable in water magnesian and selenitic, mixes badly with other cements and is of an high price.

; Cements of grappiers The production of cements of grappiers begins towards 1870. The grappiers are the hard elements that the action of water cannot make fall out of powder during the extinction of lime, and that the bolters rejected. They was the limiting incuits, limes, limes and parts too charged out of clay with marly limestones.

Constituting a significant loss for the manufacturer, one leads to the Teil (Ardèche) to draw from it part by creating cement of grappiers, whose quality could be remarkable. This a little bastard product disappeared definitively from the market with the war 1914, but one finds it in the handbooks of architecture of the Années 1930.

; Cement of slag Cement called also cement Pozzolana, obtained starting from Dairy of blast furnaces mixed with extinct fat lime and hydraulic lime.

The slag, to acquire power, must be cooled abruptly on the outlet side of the furnace while being thrown in water. It contains sulfides of calcium which oxidize with the air, which gives him a green color, and disaggregate the mortars, but it hardens considerably, although slowly, in moist environment.

It is also a mixture of hydrate of powder lime and pulverized hydraulic gangues or artificial pozzolana.

In Germany, the beginning of the manufacture of cement with 30 % of slag goes back to 1901, but it was approved only in 1909. In this same country cements containing until 70 % of slag manufactured as of 1907 and were approved in 1909. In France, before 1914, one used especially the slag with lime coming from the area Is. The schedules of conditions French mention it for the first time in 1928 and admit it in work with the sea in 1930.

; Slow cement Slow-setting cement, more than eight hours; to see natural cements or Portland cement.

; Heavy or overcooked cement Cement overcooks with 1 450°C, therefore slow with the catch.

; Mixed cement Name what gave the factories of the north of France to the forgeries artificial and sold elsewhere under the name of natural Portland, composed of natural cement and lime grappiers mixed in variable proportions.

; Natural cements The natural cements are quick-setting or slow cements, even half-slow. They are obtained by the cooking of Calcaire Argileu X naturally of good composition.

The natural cements are divided into two classes:

quick-setting cements, cooked with 900 °C like limes, which make taken in less than 20 min;
slow cements, cooked in a state close to pasty fusion with 1 450 °C, which make taken into 1 or several hours.

Intermediate varieties were obtained directly or by mixture and were called half-slow.

Towards 1880, the natural cements of the surroundings of Grenoble (greater producing area) resulted from the limestone cooking marly container from 23 to clay 30%, more or less pure. Once cooked, they contained 35 to burnt clay 45% and 65 to lime 56%. The proportion of the clay considered as best is from 23 to 24% in limestone and of 36 in cement. They gave according to their cooking of the slow or prompt natural cements. Only the natural quick-setting cement is still manufactured.

; Portland cement Portland cement is artificial cement obtained by cooking close to the state of pasty fusion of 1 450 °C of limiting limes mixed closely (limestones telling from 20 to clay 25%) and a long time called burned limes, or of rocks limestones and carefully proportioned argillaceous rocks. It is the current name of slow cements. The Portland cement denomination comes from the Portland cement factories to the United Kingdom, where cement had the same color as the stones of this area.

; Natural Portland cement Unsuitable name of the natural cements of Isere. See natural cements.

; Quick-setting cement (or Roman cement) Technically, the quick-setting cement is an eminently hydraulic lime, cement obtained by cooking with 900 limestone °C containing from 23 to clay 30% and whose catch is carried out into ten or twenty minutes. Generally, it is a natural cement, cement coming from the simple cooking of a gangue having naturally the good proportions of limestone and clay. The stone, on the outlet side of the furnace, remains some time with the air and absorbs moisture, then it is bolted, preserved out of silos and is bagged. This cement reaches its maximum of hardness after a few days.

The quick-setting cement is manufactured since the end of the 18th century. It was called a long time Roman cement in the north of France, the countries Anglo-Saxon and of Eastern Europe in spite of the fact that this commercial qualification is absolutely unsuitable. The large producers were on the island of Sheppey in the United Kingdom and to Vassy, Pouilly and Grenoble (still in activity) in France.

The quick-setting cement was used a long time to make mouldings with the gauge or to manufacture factitious moulded cement stones (of 1820 with 1920 env). It is today also used as cement to seal, natural additive in the pargets of lime, maritime work and to manufacture mouldings of art in particular in the Alps and in Italy of north (French cement importation, the prompt one of Pérelle and the Door of France of the Vicat company, the producing last).

; Sulphated cement Sulphated cement was invented in 1908 by Hans Kühl. It not very manufactured in Germany, but was exploited industrially in Belgium and France starting from 1922 and until in 1965.

; Roman cement: to see quick-setting cement

Sources

Cement went back book to Walter H. Duda
Natural cement Cédric Avenier S. to dir., Bruno Rosier, Denis Sommain, Grenoble, Glénat, 2007,176 p.

External bonds

Cembureau (Cembureau), European association
Cenorm, CEN - “European Committee for Standardization "
Industry French cimentière
Gefic Grouping of the Companies Suppliers of the Industry of the Cement factory
Portland cement Cement Association (PCA), North-American association
Chemistry of the cements, Company of cements of Ain El Kebira (document pdf, 131p, 573 Kibi O)
French company of Chemistry, Productions of cements: compositions, types, localization of the factories (given French and world)
'' www.cimento.org - Tea World off the Cement ''
'' www.cimentobrasil.com - Brazil Cement ''

Simple: Cement

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