Cement concrete technology (english)

                Cement Concrete Technology

What is concrete :

Concrete, in the broadest sense, is or mass made by the use Cementing medium. on Concrete is made with several types of cement and also containing pozzolan, fly ash, blast furnace slag a admintures, polymers, fibres and so on, and these concrete can be heated, Steam Culed, autoclaved vacuum-treated, physically pressure, Shock vibration ae

Concrete = cement +CA+FA +water+ Admistest

cement: The word cement usually means Portland cement wad in civil engineering works which sets well under water

hardness quickly and attains Strength.

Cement differs from line by the property that it does not Slake but sets more Strength on setting. The setting power of cement is more than that of lime but cement is similar in many - respects to good quality hydraulic lime.

'n the most general sense of the word | Cement in a binder a substance which sets and hands independently, and can bind their materials together The most important use Coment in the production of mortar and concrete, toe bording of natural or artificial aggregates.

to form a Strong building material which is durable against normal environmental effects. Cement is divided into two categories

1-Natural cement
2- Artificial Cement

1 natural cement

Manufactured by buning & crushing of Stones, Containing to 40% of clay and consisting of carbonate  of lime is brown in colour and sets quickly when mixed with water depends upon clay content.

-NO great ultimate Strength.

-Roman Cement is variety of natural cement

2- Artificial Cement

portland Cement Is validity of serial artificial Cement pooganed by burning together a mixture of Siliceous, argillaceous and calcareous materials in particle fusion at a temperature of 1400° to 1450°c.
By doing it is called clinker, is obtained  it cooled and turn ground to require finence to  get cement.

properties of Cement

Following are the  important properties of good cement.

-it gives Strength to masonry.

- It is easily workable.

-It offers good resistance to moisture.

-It s an excellent binding material

-It possess a good plasticity.

-it hardens early .

-comperision  B/w lime and Cement

 1-The Cement can be used under conditions and circumstances which are not favourable for lime.

2-The Cement, when converted into paste - form, Sets quickly.

3-The Colars of cement & line are different when water is added to cement less amount of heat is produced and there is no Slaking action.

Ingredients of cement

 The two basic ingredients of Cement are
1- angillaeous
2- and calcareous.

Ingredients of ordinary Cement.

Ingredients                               % Range

Lime Cao).                                     62-67
 Silica (SiO2).                                 17-25
 Alumina (ALOS).                         3-8
Calcium Sulphate (ca S04).        3-4
 Iron Oxide (Fe,02)                       3-4
 magnesia (Mgo)                          1-3
Sulphur (S)                                    1-3
Alkalies.                                         0.2-1

Constituents f portland Cement.

lime-62% Magnesia-2%

Silica - 22%.

Alumina-5%

Calcium Sulphate-4%.

Iron oxide - 3%

Alkalies - 1%

Sulphar- 1%

Function of Ingredients of Cement.

Lime: Test makes the Cement Sound and strong.

 The lime in excess quantity makes Cement -
unsound and causes the Cement to expand and disintegrate.

Silica: It provide strength to the cemment due to the formation of dicalcium and tricalcium slicates. The Silica In excess quantity causes the cement to set slowly.

Alumina: It provides quick Setting property to the Cement and lowers the clinkering temperature.

Iron oxides:  It provides colour, hardness and strength to the cement. It also helps the fusion of raw materials during the manufacture of cement.

Magnesium oxide: It provides hardness and colour to the cement, when present in Small quantity. The magnesium oxide in excess quantity makes the cement unsound.

Sulphur: It makes the Cement Sound, when present in small quantity. The Sulphur in excess quantity makes the cement unsound.

Alkalies: There should be present in Small quantities. The alkalies in excess quarentity will cause efflorescence.

Harmful Ingredients of Cement


 Following are ingredients which effects quality of Cement.

1- Alkali oxides.

2- Magnesium oxide.

If amount of alkali oxides exceeds (1%).

it leads to the failure of concrete made from that cement. If the Content of magnesium oxide exceeds 5%), it causes Cracks affect metal or concrete hardens.

Hydration of cement

The Chemical reaction b/w Cement and water s called hydration of cement or Cement hydration. The phenomenon by virtue of which the plastic Cement changes to a Solid mass is known as Setting of Cement!

The Phenomenon by virtue of Cement paste Sets and develops Satara Strengh is known as hardening of Cement

when water added to cement, the Ingredients of Cement react Chemically with water and forms various complicated - chemical compounds. The important compounds formed during the setting action of Cement are-

1. Tricalcium aluminate (C3A)
2. Tetra-calcium alumino-ferrite(C4Af)
3. Tri calcium silicate(C3s)
4. Dicalcium Silicate+(C2s)

Tricalcium aluminate and Tetra-calcium alumino ferrite compounds formed within 24 hours after addition of water.

Dicalcium Silicate Compounds formed within a week or so after addition of water to cement and its mainly responsible for importing Strength to the cemment in early period of Setting, Dicalcium silicate compounds is formed very Slowly and it is mainly responsible for giving progressive Strength to the cement.

Heat of hydration-

The reaction of Cement with water is exothermic. The reaction liberates a Considerable quantity of heat. This liberation heart is called heat of hydration. on  maning Cement with water , a rapid heat evaluation ,lašting a few minutes, occurre. This - heat evolution is probably due to the reaction of Solution of aluminates and Sulphates.