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Ordinary Portland cement

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  Ordinary Portland cement Ordinary Portland cement is the most common type of cement that used in general across the world. concrete, mortar, stucco, and non-specialty grout are the main ingredients in this cement. Main chemical constituents of ordinary Portland cement Lime (CaO) 60-65 % Silica (SiO2) 17-25% Alumina (Al2O3) 3-8% Iron oxide (Fe2O3) 0.5-6% Magnesia (MgO) 0.1-4% Sulphur trioxide (SO3) 1-3% Alkaline 0-1% Uses of Cement OPC cement is used for general construction purposes where special properties are not required. It is used in reinforced concrete buildings, bridges, pavements, and where soil conditions are normal. It is also used in concrete masonry units and in addition to that also uses in where the concrete is not subject to special sulphate hazard or the heat generated by the hydration of cement is not objectionable. Advantages of OPC Cement It has great resistance to cracking and shrinkage but has less resistance to chemical attacks. It is used in the construction wo
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Rate Analysis for Cement mortar

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  Rate Analysis for Cement mortar Rate analysis for cement mortar requires estimation of materials for cement mortar, i.e. quantity of cement and sand required for 1m3 for various proportions, i.e., CM 1:2, 1:4, 1:6, 1:8 etc. So, let us first calculate quantity of cement and sand required for 1m3 of cement mortar. For 1m3 of wet cement mortar, 1.3m3 of cement and sand is required, due to presence of voids in sand in dry state. So, cement and sand quantity is calculated for 1.3m3 of cement mortar. Estimation of Materials for Cement Mortar: Steps for calculation of quantity of cement and sand for cement mortar: Consider, we want to calculate quantity of cement and sand for CM 1:X, where, 1 is proportion of cement and X is proportion of sand. Then, quantity of cement shall be calculated as: Quantity of cement = Above formula gives quantity in volume. To calculate the quantity of cement in number of bags, we have to divide it by volume of cement of one bags. The volume of one bag of cement
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Storage of Cement

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  Storage of Cement Proper place for cement storage, duration, arrangement, atmospheric moisture content etc. is necessary after the process of manufacturing and before using it in the construction site.Storage of cement should be done with care as due to cement hygroscopic nature, the cement absorbs moisture from the atmosphere very actively and hardens like stone which cannot be used for constructional purpose.  During storing of cement precautions should be taken against atmospheric moisture content, duration of cement storage, place of storage, arranging cement bags, withdrawal of cement bags.Moisture content is dangerous for cement. Presence of moisture in cement will make cement useless so it should be stored that it cannot expose to the atmosphere. The absorption of moisture from atmosphere will also depends up on the quality of cement. If the cement is finely grained and very good in quality, then it will absorb moisture vigorously. Hence, extra care should be taken for this ty
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Fly Ash

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  Fly Ash Fly ash is the finely divided residue that results from the combustion of pulverized coal and is transported from the combustion chamber by exhaust gases. It is produced by coal-fired electric and steam generating plants. Types of Fly Ash There are two types of fly ash Class C Fly Ash : It is produced from the combustion younger lignite or subbituminous coal. Class F Fly Ash : It is produced from the burning of harder bituminous coal and older anthracite. Application of Fly Ash           Fly Ash is a prime material in many cement products like pouring concrete, Concrete block and brick. Mainly it is used in Portland cement concrete pavement or PCC pavement. By using fly ash in PCC road construction projects, it gives remarkable economic benefits as it is a great deal of concrete. It is also used in embankment construction. It is used in roller compacted concrete dams. It is used in the making of fly ash bricks. In the geopolymer it is used as component. It is used as a soil s
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Role of Gypsum in Cement

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  Role of Gypsum in Cement Gypsum is a soft sulfate mineral composed of calcium sulfatedihydrate, with the chemical formula CaSO4·2H2O. It is used for a variety of manufacturing, industrial and agriculture uses. The colour of gypsum is white, grey, brown and red. When the production process of cement, clinkers are formed and gypsum is added when it is cooled down then the mixture sent to final grinding process. For ordinary Portland cement it uses upto 3-4% and for quick setting cement it can be reduced to 2.5%. Role of gypsum in Cement When water is added into cement hydration process starts, water reacts with C3A and hardens. This process occurs very quickly and doesn’t allow time for transporting, mixing and placing. So Gypsum is used to slow down the hydration process. When gypsum is added into the cement and water is added to it, reaction with C3A particles tales place to form ettringite. This ettringite is initially formed as very fine-grained crystals, which form a coating on th
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Fineness of Cement

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  Fineness of Cement Fineness of cement is property of cement that indicate particle size of cement and specific surface area and indirectly effect heat of hydration. Why it is so important? Finer cement provides a greater surface area for hydration hence faster development of strength occurs so it has a more relevance with the rate of hydration and rate of gain of strength. Methods to obtain Fineness of Cement Sieve Method Air Permeability Method (Blaine Method) Sieve Method Apparatus required for this method is Sieve lead, Sieve with Pan, Weighing balance and Sieve shaking machine. Collect a sample of cement and rub with your hands. The Fineness test sample should be free of lumps.  Take 100 gm of cement sample and note its weight as W1.  Drop 100 gm of cement in 90 µm sieve and close it with the lid.  Now, shake the sieve with your hands by agitating the sieve in planetary and linear movements for 15 minutes. After that take weight the retained cement on the 90 µm sieve as W2. Finen
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Physical Properties of Cement

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  Physical Properties of Cement Following are the physical properties of Cement : Ø  Fineness of Cement Ø  Soundness Ø  Consistency Ø  Strength Ø  Setting time Ø  Heat of hydration Ø  Loss of ignition Ø  Bulk density Ø  Specific gravity (Relative density) Fineness of Cement Fineness of cement is the property of cement which shows the particle size of cement and specific surface are. It is directly related to heat of hydration and it helps to gain cement strength. Fineness of good cement can be achieved through the grinding of clinker in cement manufacturing. Fineness of cement is tested in two ways : (a) By sieving (b) By determination of specific surface Soundness of Cement Soundness of cement is the property that shows the ability of a hardened paste to retain its volume after setting. If cement is having lack of soundness it is called unsound which means there is a presence of excessive amount of hard-burned free lime or magnesia that means it is subjected to delayed destructive exp
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