Cement Industries

Welcome to my presentation

Md. Hafizur Rahaman ID NO: 20121107046

Department of “ACCE”

BSMRSTU.

My presentation topic is “Cement Industries”

What is cement Cement ?

• A powdered materials which initially have plastic flow when mixed with water or other liquid, but has the property of setting to a hard solid structure in several hours with varying degree of strength and bonding properties”

• Picture of cement

Types of cement• Generally 4 types …….1. Portland cement: - generally mixture of tri -calcium silicate , di-calcium

silicate, and tri-calcium aluminate.C3S and C3A is more important of them.2. Pozzuolana cement:- generally made from tofus of volcano. (pozzuola in

Itali). Tofus turned into cement when only it is finely grounded and mixed with lime.

3. Calcium aluminate cement: -some time it is called high alumina cement . when the mixture of Al2O3 and CaCO3 is melting for industrial production.

4. Special or corrosion resistance cement:- phenolic Sulphur, Silicate cement.

History • In 1824, Portland cement was invented and named

by Joseph Aspdin.• Portland cement: He named because the cement

he made was as same as ,Portland rock (stone)• Natural cement (puzzoli ) in Itali: mixture of burnt

silicate and lime , from volcanic stuff ,volcanic tufa.

What is Portland cement

• It is the mixture of fine powder at definite ratio of calcium aluminate and hydraulic (jalbahi) calcium silicate when come in contact with water , hardening to make strong concrete.

Types of Portland cement • Depending upon the rate of setting ,heat evolution and strength characterstics, Portland

cement is of various types;

Type 1. regular Portland cements- generally used to make concrete ,e.g . white cement ,which contain small amount of Fe2O3.

Type 2. modified Portland cements-used where waters heat neutralization is necessary.it produced for the neutralized reaction of sulfate.

Type 3. high early strength Portland cements-ratio of lime and sand is greater than regular Portland cement . contain greater tri calcium silicate and quickly hard than regular Portland cements. Used appropriate for road construction.

Type 4. low heat Portland cements-contain high rate of tetra calcium aluminate ferrite and di calcium silicate. low heat emit during setting.

Type 5. sulfate resisting Portland cements-resist sulfate reaction. contain tetra calcium alumina ferrite in high rate and tri calcium aluminate in low rate than regular Portland cement .

Other types of cementAcid resisting cement- capable of resisting corrosion by acids in the post hardening stage. It is used in concrete and reinforced concrete structures to be exposed to corrosive action of mineral and organic acids.White cement- the color of the ordinary Portland cement is greyish-black due to presence of iron oxide present. If iron oxide can be avoided by suitable selection of raw materials and produce white cement.Colored cement- obtained by mixing white or grey Portland cement with suitable colored pigments. For getting blue, green, black and red cements, the pigments that are respectively cobalt blue, chromium oxide, carbon black and iron oxide.

Raw materials for the manufacture of portland cement

Limestone: CaO, Fe2O3Clay: SiO2, Al2O3 The raw materials includea) Calcareous materials: eg.limestone

(containing 65-80% CaCO3), calcium carbonate sludge, marl, chalk and alkali waste.

b) Siliceous or Argillaceous materials: e.g silica, iron oxide and alumina.

Cement manufacturing process• Two process: 1.Wet process: older and used mostly in INDIA & EUROPE 2. Dry process: invented in America and used thereThe choice between two process is usually govern by the following factors 1.Physical condition of available raw materials. 2.Climate surrounding the place of manufacture 3.Cost of fuel.

Comparison between dry and weight process

• If limestone and clay are soft, climate is fairly moist, and the fuel is cheap, the wet process is preferred.

• The dry process is employed, if the limestone and clay are hard.• Wet process is more common and is almost universally employed for the

manufacture of cement.• Dry process is slow and cement produced is of low quality. • In wet process, the fuel consumption is higher, process is comparatively faster,

the cement produced is of superior quality.

• Manufacture of Portland cement

Figure: Manufacture of Portland cement

Clinker

1.Raw materials are crushed, screemed & stockpiled.

2.Raw materials are mixed with definite proportions to obtain “raw mix”. They are mixed either dry (dry mixing) or by water (wet mixing). 3.Prepared raw mix is fed into the rotary kiln.

4.As the materials pass through the kiln their temperature is rised upto 1300-1600 °C. The process of heating is named as “burning”. The output is known as “clinker” which is 0.15-5 cm in diameter. Clinker is cooled & stored.5.Clinker is ground with gypsum (3-6%) to adjust setting time.6.Packing & marketting.

Reaction at the kiln• Evaporation zone (100-500)c: To remove crystal water.

• Calcining water (600-900)c: To break Calcium carbonate to form calcium oxide and carbon dioxide.

• Reaction zone (900-1400)c: C2S, C3S, C3A, C4AF.

Reactions:• CaCO3 = CaO + CO2• 2CaO+SiO2 = 2CaOSiO2• 3CaO+SiO2 = 3CaO.SiO2• 3CaO+Al2O3 = 3CaO.Al2O3• 4CaO+Fe2O3+Al2O3 = 4CaO.Fe2O3.Al2O3 Generally (2-3%) Gypsum is also added to the clinker before grinding. The function of gypsum in cement is to slow down the time of setting. C3A + 6H2O = C3A.6H2O + Heat

Function of cement manufacturing constituents

• Lime( CaO)- is the principal constituents of cement. Excess of lime and lesser than needed both reduce the strength of cement.

• Silica(SiO2)- imparts strength to cement. • Alumina(Al2O3)- increase the rate of setting but excess of Alumina weakens

the strength of cement.• Gypsum(CaSO4.2H2O)- retards the rate of setting of cement and actually

enhances the initial setting time of cement.• Iron oxide(Fe2O3)- gives color, strength and hardness to cement• SO3- in excess reduces the soundness of cement.• Alkalies- should be present in small amounts. In excess, they cause the

cement to become efflorescent.

Setting of cementThe various compounds that contributes to the heat of hardening are: C3A>C3S>C4AF>C2SStrength contribution of various compounds in Portland cement is , 1 day C3A>C3S>C4AF>C2S 3 days C3A>C3S>C4AF>C2S 28 days C3A>C3S>C4AF>C2S 2years C2S>C3S>C4AF>C3A

Soundness of cement Soundness is defined as the volume stability of cement

paste. The cement contain definite amount of free lime is called

sound cement. The cement contain lime greater or lower than definite

amount is called unsound cement. If free lime in cement is not have required amount, the

cement quality is not well.

Uses Main use is in the fabrication of concrete and mortarsModern uses

Building (floors, beams, columns, roofing, piles, bricks, mortar, panels, plaster)Transport (roads, pathways, crossings, bridges, viaducts, tunnels, parking, etc.)Water (pipes, drains, canals, dams, tanks, pools, etc.)Civil (piers, docks, retaining walls, silos, warehousing, poles, pylons, fencing) Agriculture (buildings, processing, housing, irrigation)

USES

Construction of buildings, roads ,

bridge etc.

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INSHALLAH.