Topic: CEMENT

1. TOPIC: CEMENT
Cement is the mixture of calcareous ,siliceous , argillaceous and
other substances . Cement is used ad a binding material in mortar ,
concrete ,etc.

2. A. Composition of Cement:
The ordinary cement contains two basic ingredients namely
argillaceous and calcareous. In argillaceous materials the clay
predominates and in calcareous materials the calcium carbonate
predominates. A typical chemical analysis of a good ordinary cement
along with the desired range as shown in table below

3. B. Manufacturing Process:
The entire manufacturing process is done in a modern manufacturing plant as shown in the
figure and is now controlled through a microprocessor based programmable logic control
system to maintain a consistently uniform quality of cement and a high rate of production.
Following three operations are involved in the manufacture of all kinds of cements:
1. Mixing of raw materials
2. Burning
3. Grinding

4. 1. Mixing of Raw Materials:
The raw materials such as limestone or chalk and shale or clay may be mixed either in dry
condition or in wet condition. The process is accordingly known as the dry process or the wet
process of mixing which is described through tree diagrams as following
1.1: Dry Process:

5. 1.2: Wet Process:

6. 2. Burning:
The burning is carried out in a rotary kiln as shown in figure. A rotary kiln is
formed of steel tubes. Its diameter varies from 2.50 m to 3 m. Its length varies
from 90 m to 120 m. It is so arranged that the kiln rotates at about one to three
revolutions per minute about its longitudinal axis. The corrected slurry is injected
at the upper end of kiln. The material is then heated to temperature of nearly
1400 C to 1500 C. In burning zone the calcined product is formed and nodules
are converted into small hard dark greenish blue balls which are known as the
clinkers.

7. 3. Grinding:
The clinkers as obtained from the rotary kiln are finely ground in ball mills and tube mills.
During grinding a small quantity about 3 to 4 percent of gypsum is added it acts as retarder
and delays the quick setting action of cement when water is added to it. The grinding of
clinkers in modern plants is carried out in the cement mill which contains chromium steel
balls of various sizes. These balls roll within the mill and grind the mixture which is collected
afterwards

8. C. PROPERTIES OF CEMENT:
• Following are the important properties of a good cement which
primarily depend upon its chemical composition, thoroughness of
burning and fineness of grinding :
• It gives strength to the masonry.
• It is an excellent binding material.
• It is easily workable.
• It offers good resistance to the moisture.
• It possesses a good plasticity.
• It stiffens or hardens easily.

9. D. TYPES OF CEMENT
1. RAPID HARDENING CEMENT
It gets strength faster then opc. It contains more tricalcium silicate & is more finely ground & it
releases more heat.

10. 2. QUICK SETTING CEMENT:
IT SETS FASTERS THAN
ORDINARY PORTLAND CEMENT.
& ITS INTIAL SETTING TIME IS 5 MINUTE & FINAL SETTING TIME IS 30 MINUTE.
INTIAL SETTING BEING VERY LITTLE THERE IS ALWAYS DANGER OF CONCRETE
HAVING DURING MIXING & PLACING.

11. 3. HIGH ALUMINA CEMENT:
It is manufactured by fusing together a mixture of bauxite and lime in correct proportions
and at high temperatures the resulting product is ground finely. It is of black colour and
resists well the attack of chemicals.

12. 4. PORTLAND SLAG CEMENT:
It is obtained by mixing Portland cement clinker gypsum & granulated slag in proper
proportion & grinding it finely.
1. It has lesser heat of hydration.
2.It has better resistance to soil.
3. It has better resistance to acidic water& alkali metals.

13. 5. LOW HEAT CEMENT:
Heat generated by cement may cause crack in structure. So heat generation can be
controlled by keeping the % of tri-calcium aluminates & tri calcium silicate low.

14. 6. AIR ENTERING CEMENT:
It is cement mixed with small amount of air entering material at time of grinding like
resins vinsol oil fat & fatty acids. Which forms bubble in concrete.

15. 7. COLOURED CEMENT:
By mixing some pigments, opc could be given red blue yellow colours in ratio 5:10 in cement.

16. 8. HYDROPHOBIC CEMENT:
It is cement that does not deteriorate very little during long storage under moisture
conditions it is obtained by adding some hydrophobic agents to opc.

17. 9. MASONRY CEMENT:
It is obtained by mixing opc clinker with inert material such as lime stone dolomite &
gypsum & plasticizer.

18. 10. CEMENT WATER PROOFERS:
These are added to cement mortar to make it impervious &water proof they may in
powder form liquid form & paste form.

19.  Following are some of tests performed on cement. The first one is
explained in detail:
1. Consistency test of cement paste
2. Soundness test
3. Setting Time test
4. Fineness test
5. Compressive Strength test
6. Tensile Strength test
E. TESTING OF CEMENT:

20. 1. CONSISTENCY TEST ON CEMENT PASTE
• 1.1: Significance
• This test method is used to determine the amount
of water required to prepare the hydraulic
cement pastes with normal consistency, as
required for certain standard tests.

21. 1.2: STANDARD CONSISTENCY
• The percentage amount of water which is required to prepare standard cement.
• When vicat plunger penetrate under 30mm to 35mm in paste the reading taken is known
as standard consistency or normal consistency of cement paste.

22. • Vicat apparatus
• Spatula
• Mould
• Distilled water
• Ordinary Portland cement
• Electrical balance
• Trowel
1.3: APPARATUS AND MATERIALS

23. 1.4: PROCEDURE:
• Take ordinary Portland cement of 500 grams and weight it in the
electrical balance.
• Take 26-33% of water to cement Say in first trial take 26 % water in a
graduated cylinder.
• Now take a pot and put the cement and water in it and mix with the
help of trowel.
• Form the cement paste into a ball by hands then Press the ball into
the larger end of the conical mould, held in the other hand by
completely filling the mould with cement paste.
• Remove the excessive cement paste from the mould with the help of
spatula and place the mould under the plunger needle of 1mm.

24. 1.5: PRECAUTIONS:
• The mixing of cement should be done in non-porous
glass plate.
• The plunger needle should be clean every time before
its penetration in the cement paste.
• Vicat apparatus should be free from vibration during the
penetration.