2. CEMENT
Cement is a powdery substance made by calcining lime and
clay ,mixed with water to form mortar or mixed with sand ,
gravel, and water to make concrete
•Types of cement
1.Rapid hardenging Cement
2.heat cement
3.Sulphates resisting cement
4.Blast furnace Slag cement
5.High Alumina Cement
6.White Cement
5. 1.LIME (CaO) :-
•Sufficient quantity of silica should be present in cement to dicalcium
and tricalcium silicate.
•Silica imparts strength to cement
•Presence of lime in a sufficient quantity is required to form silicates and
aluminates of calcium.
•Deficiency in lime reduces the strength of cement.
•Deficiency in lime causes cement to set quickly.
•Excess lime make cement unsound.
•Excessive presence of lime cause cement to expand and disintegrate.
2.Silica (Sio2) :-
6. 3.ALUMINA (Al2O3) :-
• Impart the quick setting time
• Act as Flux
• Lowers the clinker temperature
Excess :-
• Excess alumina weaken the cement.
4.MAGNESIA: MAGNESIUM OXIDE(MGO) :-
•Magnesia should not be present more than 2% in cement.
•Excess magnesia will reduce the strength of the cement.
7. 5. Iron oxide (Fe2O3) :-
•Iron oxide imparts color to cement.
•It acts as a flux.
•At a very high temperature it imparts into chemical reaction with
Calcium and Aluminum to form tricalcium aluminoferrite.
•Tricalcium Aluminoferrite imparts Hardness and strength to cement
6. Calcium Sulfate ( CaSO4) :-
•This is present in cement in the form gypsum(CaSO4.2H O)
•It slows down or retards the setting action of cement.
8. 7. SULFATE (SO4) :-
•Should not be present more than 2%.
•Excess Sulfur Trioxide causes cement to unsound.
8. ALKALINE:
•Should not be present more than 1%.
•Excess Alkaline matter causes efflorescence.
10. 1. Determines the physical and mechanical
2. Characteristics of the cement
3. Determines its chemical activity
4. Determines its scope of use
5. Determines the cost
•IMPLICATIONS OF COMPOUND COMPOSITION
11. 1) TRICALCIUM ALIMUNATE (C3A) :- 3 TO 14%
1) High heat evolution
2) Formed with in a day
3) Early strength
210 cal/gm-----3days
310 cal/gm-----90day
Heat of hydration
12. 2)TETRACALCIUM ALUMINOFERRITE (C4AF)
1) Formed within day
2) influence on color (Dark color) ; so it is less used in white concrete
(1 % to 2 %) only
3) Contributes little strength
4) Low temperature
Heat of hydration
70 cal/gm------3 days
100 cal/gm---90 days
13. 3) TRICALCIUM ALUMINATE (C3A):-(45%-65%)
1) Formed within a weak
2) Early strength of concrete
3) 50%-60% strength to concrete
4) Heat of hydration is 120 cal/gm
4)DICALCIUM ALUMINATE (C2A):-(15%-35%)
1) It take year to form
2) Progressives strength to cement
3) Heat of hydration is 62 cal/gm
14. PORTLAND CEMENT TYPES (ASTM C150)
1. Type I – Normal (OPC)
2. Type II – Moderate Sulfate Resistance
3. Type III – High Early Strength
4. Type IV – Low Heat Of Hydration
5. Type V – High Sulfate Resistance