Portland cement is the most common type of cement In the most general sense of the word, a cement is a binder, a substance which sets and hardens independently, and can bind other materials together. The word "cement" traces to the Romans, who used the term "opus caementicium" to describe masonry which resembled concrete and was made from crushed rock with burnt lime as binder in general use around the world, because it is a basic ingredient of concrete Concrete is a construction material composed of cement as well as other cementitious materials such as fly ash and slag cement, aggregate (generally a coarse aggregate such as gravel, limestone, or granite, plus a fine aggregate such as sand), water, and chemical admixtures. The word concrete comes from the Latin word "concretus" (, mortar, stucco Stucco or render is a material made of an aggregate, a binder, and water. Stucco is applied wet and hardens to a very dense solid. It is used as a coating for walls and ceilings and for decoration. Stucco may be used to cover less visually appealing construction materials such as concrete, cinder block, or clay brick and adobe and most non-specialty grout Grout is a construction material used to embed rebars in masonry walls, connect sections of pre-cast concrete, fill voids, and seal joints . Grout is generally composed of a mixture of water, cement, sand and sometimes fine gravel (if it is being used to fill the cores of cement blocks). Sometimes color tint is applied as a thick liquid and. It is a fine powder produced by grinding Portland cement clinker (more than 90%), a limited amount of calcium sulfate Calcium sulfate is a common laboratory and industrial chemical. In the form of γ-anhydrite , it is used as a desiccant. It is also used as a coagulant in products like tofu. In the natural state, unrefined calcium sulfate is a translucent, crystalline white rock. When sold as a color-indicating variant under the name Drierite, it appears blue or which controls the set time, and up to 5% minor constituents (as allowed by various standards).
As defined by the European Standard The European Committee for Standardization or Comité Européen de Normalisation , is a private non-profit organisation whose mission is to foster the European economy in global trading, the welfare of European citizens and the environment by providing an efficient infrastructure to interested parties for the development, maintenance and EN197.1, "Portland cement clinker is a hydraulic Hydraulic lime is a variety of slaked lime used to make lime mortar. Hydraulicity is the ability of lime to set under water. Hydraulic lime is produced by heating calcining limestone that contains clay and other impurities. Calcium reacts in the kiln with the clay minerals to produce silicates that enable the lime to set without exposure to air material which shall consist of at least two-thirds by mass of calcium silicates (3CaO.SiO2 Alite is a name for Tricalcium Silicate, Ca3SiO5, sometimes formulated as 3CaO.SiO2 . It is the major, and characteristic, mineral in Portland cement. The name was given by Törneborn in 1897 to a crystal identified in microscopic investigation of portland cement. Alite is a name in common use in the cement industry, and is not a recognised and 2CaO.SiO2) Belite is an industrial mineral important in Portland cement manufacture, a name for dicalcium silicate, Ca2SiO4, sometimes formulated as 2CaO.SiO2, the remainder consisting of aluminium- and iron-containing clinker phases and other compounds. The ratio of CaO to SiO2 The chemical compound silicon dioxide, also known as silica , is an oxide of silicon with a chemical formula of Si shall not be less than 2.0. The magnesium content (MgO Magnesium oxide, or magnesia, is a white solid mineral that occurs naturally as periclase and is a source of magnesium . It has an empirical formula of Mg ) 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 Sintering is a method for making objects from powder, by heating the material in a sintering furnace below its melting point until its particles adhere to each other. Sintering is traditionally used for manufacturing ceramic objects, and has also found uses in such fields as powder metallurgy temperature, which is about 1450 °C for modern cements. The aluminium oxide and iron oxide are present as a flux In metallurgy, a flux is a chemical cleaning agent which facilitates soldering, brazing, and welding by removing oxidation from the metals to be joined. Common fluxes are: ammonium chloride or rosin for soldering tin; hydrochloric acid and zinc chloride for soldering galvanized iron ; and borax for brazing or braze-welding ferrous metals 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 Tricalcium aluminate Ca3Al2O6, often formulated as 3CaO.Al2O3 to highlight the proportions of the oxides from which it is made, is the most basic of the calcium aluminates. It does not occur in nature, but is an important mineral phase in Portland cement (3CaO.Al2O3) formed. The major raw material for the clinker-making is usually limestone Limestone is a sedimentary rock composed largely of the mineral calcite . The deposition of limestone strata is often a by-product and indicator of biological activity in the geologic record. Calcium (along with nitrogen, phosphorus, and potassium) is a key mineral to plant nutrition: soils overlying limestone bedrock tend to be pre-fertilized (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 Clay is a naturally occurring material composed primarily of fine-grained minerals, which show plasticity through a variable range of water content, and which can be hardened when dried and/or fired. Clay deposits are mostly composed of clay minerals , minerals which impart plasticity and harden when fired and/or dried, and variable amounts of, shale Shale is a fine-grained sedimentary rock whose original constituents were clay minerals or muds. It is characterized by thin laminae breaking with an irregular curving fracture, often splintery and usually parallel to the often-indistinguishable bedding plane. This property is called fissility. Non-fissile rocks of similar composition but made of, sand Sand is a naturally occurring granular material composed of finely divided rock and mineral particles, iron ore Iron ores are rocks and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in color from dark grey, bright yellow, deep purple, to rusty red. The iron itself is usually found in the form of magnetite , hematite (Fe2O3), goethite, limonite or siderite. Hematite is also known as ", bauxite Bauxite is the most important aluminium ore. It consists largely of the minerals gibbsite Al3, boehmite γ-AlO(OH), and diaspore α-AlO(OH), together with the iron oxides goethite and hematite, the clay mineral kaolinite and small amounts of anatase TiO2. It was named after the village Les Baux in southern France, where it was first discovered in 1, fly ash Fly ash is one of the residues generated in the combustion of coal. Fly ash is generally captured from the chimneys of coal-fired power plants, and is one of two types of ash that jointly are known as coal ash; the other, bottom ash, is removed from the bottom of coal furnaces. Depending upon the source and makeup of the coal being burned, the and slag Slag is a partially vitreous by-product of smelting ore to purify metals. It can be considered to be a mixture of metal oxides; however, slags can contain metal sulfides and metal atoms in the elemental form. While slags are generally used as a waste removal mechanism in metal smelting, they can also serve other purposes, such as assisting in. When a cement kiln is fired by coal, the ash of the coal acts as a secondary raw material.
Contents |
unknown
Mon, 06 Jul 2009 13:38:09 GM
Zambezi . Portland cement. who is the owner? Days are numbered for Rajar Mahtan.He sould tell the nation how he got Zambezi . Portland Cement. , thru crooked He sould say he is one of the share holder not his. He manourvered when he held that ...
