Cement manufacturing process

Cement Manufacturing process in the cement industry

Following are the steps for manufacturing of cement

➤ Step 1: extraction of raw materials:

The raw materials needed to produce cement (calcium carbonate, silica, alumina and iron ore) are generally extracted from limestone rock, chalk, clayey schist or clay. Suitable reserves can be found in most countries. 

These raw materials are extracted from the quarry by blasting. They are then crushed and transported to the plant where they are stored and homogenized.

➤ Step 2: Raw grinding and burning:

Very fine grinding produces a fine powder, known as raw meal, which is preheated and then sent to the kiln. The material is heated to 1,500°C before being suddenly and dramatically cooled by bursts of air. 

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Seggretion of concrete

Segregation Of Concrete

Segregation can be defined as the separation of the constituent materials of concrete. A good concrete is one in which all the ingredients are properly distributed to make a homo generous mixture.If a 

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Method of test bleeding of concrete

Method of Test for Bleeding of Concrete

A cylindrical container of approximately 0.01meter cube capacity, having an inside diameter of 250 mm and height 280 mm used. A tamping bar similar to the one used for slump test is used. A pipette for drawing off free water from the surface, a graduated jar of 100 centimeter cube capacity is required for test.

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Slumb test

Slump Test

Slum test is the most commonly used method of measuring consistency of concrete which can be employed either in laboratory or at site of work. The apparatus for conducting the slump test essentially consists of a metallic mould in the form of a frustum of a cone having the internal dimensions as under:

         Bottom Diameter   :  20 cm

         Top diameter          :  10 cm

         Height                    :  30 cm
Procedure :

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Seggretion of concrete

Segregation Of Concrete

Segregation can be defined as the separation of the constituent materials of concrete. A good concrete is one in which all the ingredients are properly distributed to make a homo generous mixture.If a 

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Important point most have to remember for civilengineer

Following are the important point must to remember for every civil engineer at site

➤Minimum thickness of slab is 125 mm.

➤Water absorption should not be more than 15 %.

➤Dimension tolerance for cubes + – 2 mm.

➤Compressive strength of Bricks is 3.5 N /mm2

➤Maximum Free fall of concrete allowed is 1.50 m.

➤In soil filling as per IS code for every 100 sqm 3 sample for core cutting test should be taken.

➤Electrical conduits shall not run in

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Cement

# Cement is pulverized material that develops the bending force dur to the reaction with water.

# cement may be two types
       ● hydraulic cement :  cement are not only hardens by reacted with water but also forms water resistance product. ( stable under water )
        ● Non hydraulic cement : not produce water resistance product.

# portland cement is hydraulic cement.

# Manufacture of portlant cement

Primary consituent : calcium silicate
Raw material : calcium - limestone, chalks ( CaO+CO2)
                           Silica- clays and shales (SiO2 + Al2O3 + Fe2O3 + H20)
   ( 2/3 rd of calcium + 1/3rd of clay)

# cement contained C3S or C2S, if the cement having C3S is good because it dried early and rapid hydration start that cause more strength. Where C2S dried slowly and low hydration cause less hardening.

# C3A caused fast reacting with water and may lead immediate stiffing of paste called flash set. Gypson used on it to prolong the reaction with water.

# high silica on cement prolongs the setting time gives more strength.

# high lime also increase the setting time.
# iron oxide presence on the cement is in the form of catalyst result burning process.

# Hydration of cement :
The hydration of cement is the reaction of cement with water, actually it continues for long period. Due to this heat is generate and the strucure made with the cement is hardening. It also depend upon the calcium sulphate present in the cement where C2S takes hydration in slow rate cause of not as much hardening as C3S. C3s, if presented in the cement it react faster and consequently becomes hardening.
The hydration is classified into two types :
1. Calcium silicate hydrates 
2. Tri calcium aluminate hydrates.
Calcium silicate hydrates :
2C3S+6H --------> C3S2H3 + 3 Ca (OH)2

2C2s + 4H --------> C3S2H3 + Ca (OH)2

Where, C = CaO
              S = SiO2
             H = H20
• C3S2H3 is the calcium silicate hydrate is gel.

# components present in portland cement.
CaO --> calcium oxide (C)
Al2O3 --> Alumina (A)
SiO2 --> silica (S)
SO3 --> Sulphate (S)
H2O --> water (H)
Similarly, Reactive compounds present are :
C3S - Tricalcium silicate
C2S - Dicalcium silicate
C3A - Tricalcium aluminate
C4AF- Tetra calcium alumino ferrite.
Due to mixing of above compounents a complex is formed which is called Bogue's compound.
C3S : 4.07 (C)-7.60 (S)-6.72 (A)-1.43 (F)-2.85 (š)
C2S : 2.87 (S)-0.754 (C3S)
C3A : 2.65 (A)-1.69 (F)
C4AF : 3.04 (F)
Here, terms C, S, A, F, Š and C3S etc to be represented by %.

Introduction of concrete

# Definition of concrete :
The concrete is the mixture of sand, aggregate and water and sometime admixture in required propotion.

# Hardening of concrete is cause by the chemical reaction between water and cement. And this reaction continues for

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