Definition and
introduction:
- Cement in general adhesive substance used for binding the material in building and construction which sets up,hardens and adhere to other material to bind them together. Cement is usually found in the form of a homogeneous bulk dry good.
- The composition of water and cement gives strength to the mixture to this process is known as hydration.
- The one of the important thing is when water is mixed, cement acts as an adhesive to fasten sand, gravel, and hard rock in concrete. Cement hardens both in the air and under water, and remains in its hardened state once reached. Due to their hydrating properties, constructional cements, which will even set and harden under water, are often called hydraulic cements.
- The chemical composition of water and cement compounds resulting in submicroscopic crystals are jel like material.Cement is a fine gray powder that is mixed with water and other substances to make mortar or concrete. Cement it is a chief building material for all types especially residential and commercial construction projects.
History :
- Cement is mixture which is discovered by Joseph Aspdin, before any one.
- an inspiring 19th-century British stonemason, who made hot a mix of limestone and clay in his kitchen stove, then crushed the concoction into a fine powder. The world's first hydraulic cement was made: one which will clot when water is added.
Composition:
- The main content which are used
to produce cement are silicon, calcium,iron, aluminium and other
ingredients. I saw some of the common material are shells limestone and
chalk.
- Lime or calcium oxide, CaO: it
is produced by some of the following materials such as limestone shells
chalk calcareous rock.
- Alumina, Al2O3: it is formed by bauxite, clay, recycled
Aluminium.
- Silica, SiO2: produced from old bottles clay a and sand
- Gypsum, CaSO4.2H20: limestone
-
Iron, Fe2O3: it can be developed from iron, ore, fly ash, clay, scrap iron.
Types and applications :
1. Ordinary Portland Cement (OPC)
Ordinary Portland cement is used for all type of construction work,which is suitable for all general concrete construction. 
2. Portland Pozzolana Cement (PPC) :-
In case of PPC use of pozzolanic material which is cheaper in price is used instead of expensive clinkers. In PPC the permeability is improved by by transferring soluble calcium hydroxide to insoluble cementitious product, hence durability characteristics can be achieved.
3. Rapid Hardening Cement :-
As the name suggest it develops strength rapidly as such it may be more appropriate to call it as a high early strength cement. Where form work is required to be removed early for use elsewhere , road repair works , in cold weather concrete.
4. Quick setting cement.
By reducing gypsum content in the cement early setting property can be achieved. underwater construction can be very complex for a civil engineer this cement can add great value for underwater construction.
5. Low Heat Cement.
Formation of cracks in large body of concrete due to heat of hydration has focused the attention of the concrete which produces less heat, low rate during hydration process. Lohit evolution is achieved by by reducing the content of C3S and C3A.
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