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Cement

Cement

Cement

Cement`

Def:-
Cement is a cementations material having adhesive and cohesive properties to bond inert aggregates into a solid mass of adequate strength and durability.”

Structural Cement

For making structural concrete hydraulic cements are used exclusively.
(It gains strength by hydration)
Water is needed for the chemical process (hydration) in which the cement power sets and hardens into one solid mass. Setting time of cement is varies under different atmospheric conditions.

Example

Portland cement.

Properties of Portland Cement
1)     Portland cement was made first time in England in 1824.

2)     Portland cement is finely powdered.
3)     Its color is grayish material
4)     It consists of calcium aluminum and silicate.

Manufacturing of Cement

Raw Material for Portland Cement

The common raw material from which cement is made are lime stone which provide CaO clay or shale which furnish Sio2 and Al2O3. These are ground, blended, fused to clinkers in a kiln and cooled.
Gypsum is added and the mixture is ground to the required fineness. The material is shipped in bulk or in bags containing 94 lb of cement.

Equation

Lime stone      →    Ca
Clay/shale    →        silicate
Al2O3        →           aluminum

CaCO3       Co2                       CaO     Sio2            C2S       CaO          C2S + C3S       CaO              C3S + C2S

               700-1000 C0                 1200 C0             1300C0                              1400C0

Properties of C2S and C3S

C2S    →       (Cao) 2 sio2
If we increase the amount of C2S in cement the setting time of cement will increase

C3S→ Cao) 3 sio2
If we increase the amount of C3S the early setting time of cement will be decrease

C3S       control early setting time

Chemical Composition of Cement

Belite                         C2S         →               10% – 30%
Alite                          C3S         →              45% – 65 %
Aluminates            C3A        →               5% – 12%
Ferrite                      C4AF          →            6% – 12%
Gypsum                    CaSo4            →         4% to control setting time
Alkalis                       Na2O                 →     0.2 %-0.7%
K2o            →              0.5% – 1%

Gypsum CaSodecrease the setting time of cement.

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About Mustafa

My name is Mustafa Awais, I am basically from Pakistan & Currently living in Saudia Arabia, I am Civil Engineer as well as Web Master.

3 comments

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