Definition of cement:
Cement is nothing but fine man-made powder which can used for as binder in different type of construction work.
Introduction to Cement:
- Cement is one of the most important and widely used binding material till date in construction industries.
- Cement forms a rigid solid mass when it mixed with water and consist of various properties like strength, water resistance, rigidity, porosity, hardness, durability, sustainability and easy to work with.
- And this is the reason why it is more famous binding material.
- Cement is main part of cement mortar, concrete, plastering and other activities of building construction.
- Concrete and mortar can be used to bind different materials like rocks, stones, bricks and building elements.
- Cement is generally made up of limestone, sand, clay, aluminium, iron ores and can be included chalk, shale, clay, various slags, slate, marl.
- Cement is not natural material; it is manufactured in plants. And it can be manufactured depending upon the requirements. There are various types of cement is available in market depending upon the usability and nature of work for it to be used.
- Cement is also form rigid, solid water repellent material and can be used in water proofing works.
History of Cement:
- Hydrated lime to the first hydraulic cement used by the Romans in the Middle Ages, the development of cement continued to the 18th century.
- But in 19th century the foundation is said by using cement. The Frenchman Louise Vicat laid his foundation by using Portland cement.
- In the 19th century, Rosendale cement was discovered in New York. Though its rigidity made it quite popular at first, the market demand soon declined because of its long curing time and Portland cement was again the favourite.
- However, a new blend of Rosendale-Portland cement, which is both highly durable and needs less curing time, was synthesized by Catskill Aqueduct and is now often used for highway or bridge construction.
- But today, cement has undergone to various experiments and testing. The research also had done many research in field of cement but still there is no best binding material than cement.
- Depending upon research and testing, cement has under carious evaluation till date, and we have found many types of cement which is readily available in market.
Ingredients of cement:
- Iron Oxide
- Calcium sulphate
Properties of cement:
- Fineness of cement
- Setting time
- Heat of hydration
- Loss of ignition
- Bulk density
- Specific gravity (Relative density)
- Read more about properties of cement>>>>>>
Cement is chiefly of two kinds based on the way it is set and hardened: hydraulic cement, which hardens due to the addition of water, and non-hydraulic cement, which is hardened by carbonation with the carbon present in the air, so it cannot be used underwater.
Non-hydraulic cement is produced through the following steps (lime cycle):
- Calcination: Lime is produced from limestone at over 825°C for about 10 hours. (CaCO3 → CaO + CO2)
- Slaking: Calcium oxide is mixed with water to make slaked lime. (CaO + H2O → Ca(OH)2)
- Setting: Water is completely evaporated.
- The cement is exposed to dry air and it hardens after time-consuming reactions. (Ca(OH)2 + CO2 → CaCO3 + H2O)
On the other hand, hydraulic cement is mainly made up of silicates and oxides:
- Belite (2CaO·SiO2);
- Alite (3CaO·SiO2);
- Tricalcium aluminate/ Celite (3CaO·Al2O3)
- Brownmillerite (4CaO·Al2O3·Fe2O3)
The ingredients are processed in the kiln in cement plants. The complete chemistry of the reactions is still a subject of research.
Grades of cement:
The cement used shall be any of the following and the type selected should be appropriate for the intended use.
- 33 Grade ordinary Portland cement conforming to IS 269
- 43 Grade ordinary Portland cement conforming to IS 8 112
- 53 Grade ordinary Portland cement conforming to IS 12269
- Rapid hardening Portland cement, Portland slag cement, Low heat Portland cement, Sulphate resisting Portland cement etc. etc.