Cement_ 1.pdf. CEMENT BASICS CIVIL ENGG.

CEMENT BASIC CIVIL ENGG

1. Cement I
AMMU S

2. Cement

●Cements in a general sense are adhesive and cohesive
materials which are capable of bonding together
particles of solid matter into a compact durable mass
●Its primary function being to bind the fine (sand) and
coarse (grits) aggregate particles together.

3. Cement

●Joseph Aspedin of was the first to introduce Portland
cement in 1824 formed by heating a mixture of
limestone and finely divided clay in a furnace to a
temperature.

6. 1. Lime (62-65%)
■ Imparts strength and Soundness (volume)
■ Excess- it becomes difficult to combine with other
compounds, free lime will be present in clinkers which makes
cement unsound, causes it to expand & disintegrate
Deficiency- reduces strength of cement, causes it to set quickly

7. 2. Silica (17-25%)
•Imparts Strength to Cement.
• Excess- increases strength of cement BUT increases setting
time of cement.
3. Alumina (3-8%)
•Imparts quick setting property
•Reduces clinkering temperature, if it is in excess weakens the
cement

8. ●4. Gypsum (3-4%)
●■ Present in form of calcium sulphate
●■ Used to increase initial setting time of cement
●5. Iron Oxide (3-4%)
●▪ Imparts Colour, Strength and hardness to cement
●■ It induces reddish brown tint to the cement
●6. Magnesia (1-3%)
●Imparts Strength and colour to cement (yellowish tint)
●■ Excess- makes cement unsound

9. ●Bougues compounds
●Various constituents combine in burning and form
cement clinker.
●The compounds formed in the burning process have
properties of setting and hardening in presence of
water.

11. ●They are known as Bogue compounds after the name of
Bogue who identified them.
●Le Chatelier and Tornebohm have referred these compounds
as Alite (C3S), Belite (C2S), Celite (C3A) and Felite (C4AF).

12. ●Tri Calcium Aluminate (C3A or 3Ca0.Al2O3)
●4-14% by weight
●Formed within 24 hours of addition of water in cement
●Responsible for maximum amount of heat of hydration
●It is responsible for initial set, higher heat of hydration and
greater tendency to volume changes

13. ●TetraCalcium Alumino Ferrate (C4AF or
4Ca0.Al2O3.Fe2O3)
●10-18% by weight
●It is also formed within 24 hours of addition of water to
cement
●Amount of heat of hydration evolved during formation of
this compound initially is comparatively more which goes
on decreasing with time
●It is also responsible for flash set but generates less heat

14. ●Tri Calcium Silicate (CS or 3CaO.SiO2)
●45-85% by weight
●It is supposed to be the best cementing material and is
well burnt cement
●Formed within a week of addition of water in cement
●Responsible for development of early strength of cement
in initial stages (7 days strength)

15. ●Di Calcium Silicate(C2S or 2CaO. SiO2)
●15-35% by weight
●It is formed very slowly after addition of water in cement
and may require a year of so for its formation
●It imparts resistance to chemical attack
●It is responsible for progressive strength of cement in later
stages

16. ●Note:
●✓If early strength is required- increase C3S (emergency road
work, prefabricated construction work, etc.)
●✔Strength in required to be increased in later stages-
increase C2S

17. ●Hydration of cement
●The chemical reaction between cement and water is known
as Hydration of Cement
●Heat of hydration of Ordinary Portland Cement during 7 days
is about 89-90cal/gm and during 28 days is about 90-100
cal/gm Water-
●About 23% of by weight of cement is required to carry out
the complete hydration

18. ●Hydration of cement
●About 15% of water is used up in filling voids of the cement
particles, hence effectively 38% of water (by wt of cement) is
required to carry out complete hydration
●Heat of Hydration C3A > C3S > C4AF > C2S
●Rate of Hydration C4AF > C3A > C3S > C2S

19. THANK YOU