History of cement
History of cement science
History of cement production in Iran
What is cement?
History of cement
May be centuries ago, a group of Stone-age human beings had made a fire in their camp on a stone made of lime, and enjoying its heat, overwhelmed with their thoughts, when all of a sudden a rainstorm stopped their thoughts making them escape to a shelter.
The fire set out by the rain, and the hot stone getting wet is decomposed and changes into powder. After days or months that the group comes back there, see that a strange stone has appeared.
It is probable that discovery of the lime mortar has happened in such a simple way. Historical and archeological studies reveal that record of natural cement production is historically synchronized with the production of lime.
The Phoenicians about 1.000 B.C., The Greeks in 200 B.C. and the Romans in 100 B.C. were able to produce some materials which hardened with water, The very old historical monuments, such as Pyramids of Egypt prove that the man had good knowledge of some mortars since ancient times. The Egyptians used the cooked impure gypsum mortar, while there were plenty of lime-stone under their feet. It was common to use calcinated lime-stone (lime – mortar) in the Greek and Roman civilizations, which was used in pure form, or mixture of lime-emulsion, sands and grits, broken stones, or volcanic ashes.
Historical studies show that the Iranian, too, were capable of preparing water – mortars which preserved their resistance against pressure even in places close to water. The relics remained from huge darns and bridges in various parts of Iran, such as “Eizadkhast” darn, which is the world primary arch-darn, “Karkheh” darn, and “Shadravan” darn make it certain that the Iranians were familiar with the lime hydraulic properties, sine very ancient time.
The Romans learned from the Greeks, and the Greeks learned from the Iranians how to prepare the lime, as the oldest lime-mortar has been found in Iran. The Assyrians and the Babylonians used to build their buildings with mud, gypsum, brick, mud mortar, or tar.
Chinese, too, know how to prepare lime-stone, and have used lime mortar in constructing towers of the Wall of China in approx.2.000 years ago, but the mortars found in Iran proved to be much older.
The peoples who inhabitant in the northern regions of Persian Gulf, have used a kind of mortar which held interesting hydraulic properties, with high strength. The most well-known mortar of this kind is the “Khamir-mortar” which prepared in “Khamir” port.
The port installations constructed with this kind of mortar is still remaining in some parts of “Bandar-Lenghe” and “Boushehr” port (Bandar-Bushehr).
History of cement science
The 18th and 19th centuries were the times many phenomena discovered, and scientists, also researches were much concerned with scientific and natural phenomena, one of them was the setting and hardening of mortars, which their hydraulic properties discovered by the English “John Smitten” in 1756, , and important properties of the compounds available in argil. Hydraulic setting and hardening properties of the compounds were found out by him.
The discovery followed his researches for the purpose of winning a competition under the title of’ The best mortar for reconstruction of Edison sea-light, and “Smitten” figured out during his researchers that the best mortar is made by cooking a kind of lime-stone where a mixture of stone, and some argil are available too. Pursuing the discovery by “Hygins” and “Parker” was a clue for further discoveries, so that the first measure taken by man in preparation of an artificial mixture of lime-stone and argil to make hydraulic cement was registered under the name of Wicket, from France.
But the final honor gained by an English brick-layer named Josef Speed in . He succeeded to get a very interesting hydraulic lime, by cooking a mixture of lime-stone and argil in high-temperature (In different proportions, as emulsion) , which he called it Portland Cement, and patented his invented cement on Oct. 21, 1824 and got an award from George the fourth.
The much resemblance of its color with a sort of lime-stone in Portland Island of England was the reason for the intelligent nomination. The cement made by him was duly better and superior than all the previous cements, having much more strength, for the very reason it was used in construction of the England modern Parliament which lasted from 1840 until 1852.
In this way, man entered the era of cement industrial production, and for the first time in industrial history, the first standard institute of production established by cement producers in Germany, thus the cement is the first industrial product which holds a production standard.
Industrial production of Portland Cement began from 19th century, by furnaces having a capacity of 5 tons per week, and very similar to lime-furnaces, which modifications, in parallel with the demand for this miraculous product, were made in the furnaces structure, and way of its production.
In the long run , by invention of rotating furnaces, a great pace was taken to respond the consuming market. The result of 80 years of working with the cement rotating technology led to manufacturing of furnaces with a capacity of 100.000 tons of clinker per day.
Now thousands of furnaces all over the world, where lime-stone and argil mines are available are producing the cement, are producing the cement, and make it the biggest industrial production of man by 1200 million tons.
History of cement production in Iran
That since when the cement began to be consumed in Iran is not known, but it is certain that cement entered Iran by foreigners to be used in the construction of churches, embassies, and port installations.
By the beginning of 14 century A.H. development of infrastructure works, synchronized with the world industrial changes were so high that the quality and quantity of construction traditional products did not meet the needs, and by starting the construction of trans-railway , in particular, the necessity of using the cement in bridges, tunnels and stations became more obvious.
Since the cement is a cheap but heavy weight product, and its consumption is economical when the production and consumption sites are close to each other as much as possible, therefore after a while that cement was being imported, it was decided considering abundance of raw-materials in Iran, to establish a 100 ton/day factory, out of revenues of sugar.
The decision commenced to be realized in 1931, and primary geological studies led to selection of a site in Km 7 of the South of Tehran, near to “Bibi-Shahrbanou” mountain. The establishment of the factory, with a capital of 8 million Rls completed in Feb. 1932, and its misuse started immediately (About 5 year after Japan, 60 years after America, 70 years after Germany, and 100 years after England).
By elapse of time and increase of demand for the product, the need for more factories became obvious, therefore in 1935, another factory, with a capacity of 200 tons/day purchased, and in 1936 its constructional operations started next to the previous one, resulting in misuse in 1937.
It goes without saying that cement, with its miraculous properties considered to be the main element of any construction, and no structure no any building without using the cement is conceivable.
What is cement?
Cements are adhesive materials which are able to adhere particles to each other, and make a solid substance of the components. This definition of the cement is so comprehensive which may be subject to different pastes, including liquid pastes which are used in pasting stones, or metal parts to each other, therefore our intension of cement is the kind with an origin of lime.
Cement is a soft powder, absorbent of water, and adhering of pebbles which are mainly composed of the cooked and molten compounds of calcium oxide, silicon oxide aluminum oxide, and iron oxide.
Mortar of the powder is able to set and hardened in contact with the air, or under water, and while maintaining its volume, preserves its strength too, and after 28 days of submerging, gets a minimum strength of 250 Kg/cm2
In general, the raw-materials used in production of cement, are provided from natural (mineral) resources.
For provision of the compounds primarily lime-stone, with high purity, and secondly the argil which contains little lime, but remarkable amounts of silicon, aluminum and iron oxides, are used. For more elaborate regulation of the raw materials, improving substances, such as iron, silicon stone, etc. are used.
The white cement produced and supplied for the first time by the French company of Lafarge , then as it welcomed too much, and the demand went up day by day, its production aimed by other countries too, including U.S.A in 1907, Germany in 1908, Japan in 1920, and U.K. in 1929.
Production of white cement needs more complicated technology than the gray one, and non-industrial countries have hardly been able to produce it. In Iran, Damavand cement factory, converting the 100 ton furnace, commenced production of the white cement for the first time in 1963.
Afterwards, due to the increased demand, its second furnace started white cement production in 1971 too. Currently, the said factory as well as the other cement factories of Urmia, Tabriz and Saveh, supply the market with white cement, which partly is exported to foreign countries.
To produce white cement, kaolin, instead of argil, is used, as one of the reasons for gray color of cement is the presence of iron in argil compounds. Kaolin lacks (trace) iron, and as the result, the produced clinker is almost white (light green), furthermore, its production process does not allow re-oxidation.
Consequently, due to the specific process, and high softness of the white cement, the concrete resulting from white cement has higher strength compared to the gray cement, which is considered to be a great privilege.