History of Cement Discovery
For the first time in human history, an artificial mixture of limestone and clay for cement (blue lime) was made in France by Wikat in the early nineteenth century. Wickat mixed limestone and clay and then ground the mixture with water and baked the resulting slurry. Although the result was successful, in practice this method was not practically continued in France until in the United Kingdom a bricklayer succeeded in cooking a mixture of limestone and clay (relatively different and in the form of slurry) at a high temperature as a kind of lime. Achieve incredibly interesting blue. He named this product Portland Cement and on October 21, 1824 he registered his patented cement. The reason for this naming (Portland cement) was that the concrete (artificial stone and cement) obtained from this blue lime and gravel had many similarities (especially in color) with a type of cement and lime found in the south of England and on the island of Portland. Been. Of course, this cement is different from what is now known as Portland cement and is not exactly the same.
Speedin’s work was pursued by his son William, who in 1843 mastered the technique of using higher temperatures and creating a state of perspiration during baking, which produced a significant percentage of the cement-making materials used in the molten form. And the rest is cooked. Melting means the same cooking at high temperatures, so that part of the material being cooked is melted. The cement made by William Speedin was really better and better than the previous cements and had more strength. This concrete cement was used in the new building of the English Parliament (1840-1852).
What is cement?
Cement is defined as: « “A hydraulic material resulting from the burning of a mixture of lime and clay to form clinker, then by applying the clinker powdering process, the final material will have a combination of chemical and physical properties.” »
Cement is a greenish-gray powder composed primarily of calcium silicates, calcium aluminate, and calcium ferrites. When mixed with water (hydration process) it turns into an artificial rock.
Cement compounds
The main chemical materials of cement are as follows:
| lime (CaO) | 60 to 67 percent |
| Silica (SIO2) | 17 to 25 percent |
| Alumina (Al2O3) | 3 to 8 percent |
| Iron oxidation (Fe2O3) | 0.5 to 6 percent |
| magnesium (MgO) | 0.1 to 4 percent |
| Sulfur trioxide (SO3) | 1 to 3 percent |
| Soda or potash (Na2O + K2O) | 0.5 to 1.3 percent |
Production Process
Cement production, like many other stages of production, begins in the mine, where raw materials such as limestone, silica, aluminate, ferric minerals, and other materials are obtained. These materials in terms of cement ingredients are as follows :
- Some common materials used for calcium carbonate are in limestone, gypsum, marble, marl and oyster shells.
- Some common materials used for alumina include shale, clay, slag, fly ash, bauxite, alumina and granite process wastes.
- Some common materials used for silica include sand, clay, pottery, shale, slag, and fly ash.
- Some of the common materials used for iron in iron ore are blast furnace smoke dust, pyrite clinker, mill scale and ash.
General extraction methods are in the form of surface extraction. While some silicates, such as sand, are usually extracted by dredging from lakes, rivers, and waterways. There are several underground limestone mines, but most of them are surface holes.
Cement plants are usually located in the mineral center, which saves shipping costs and reduces cement prices. After extracting the mineral used, it is crushed in a factory (screening) to produce the desired particle size.
Sometimes, the raw materials are moistened by adding water to a ball mill and form a slurry. In either case, the ground powder is transferred to a rotary kiln for heat treatment. In a rotary kiln, carbon dioxide is first released from calcium carbonates, then the raw material is melted at a temperature of about 2700 degrees Fahrenheit.
Function of cement in concrete
Cement is used in concrete and its task is only to stick the grains in order and in itself has no effect on strength and load. Therefore, good concrete is concrete that when a sample of it is broken, its stone grains are broken in the middle and the cements are not torn. Cements have calcareous roots. In other words, the main material of cement and constituents of cement is lime and the main material of cement production is limestone. Accordingly, cement is a combination of calcium oxide (lime) with other oxides such as aluminum oxide, silicon oxide, iron oxide, magnesium oxide and alkali oxides that have a tendency to cement with water and are hard in the presence of air and under water.
Types of cement
In this article, we will introduce 12 types of common and widely used cements, which are :
- Cement hardens quickly
- Sharpening
- Cement with low heat production
- Cement with high sulfate resistance
- Cement composed of kiln slag
- High alumina cement
- White
- Colored
- Pozzolani
- Aerospace
- Expandable
- Hydrographic
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