SSC JE CONVENTIONAL PAPER :
CIVIL ENGINEERING :
1.
Name of the different types of raw materials
used for the manufacture cement ? What is the hydration of cement and heat of
hydration ? How is the is the aggregate classified according to size , shape ?
write down the function of admixtures in concrete? 5+10+15+15
Answer :
1)
Name of the different types of raw materials
used for the manufacture of cement consists mainly lime , silica , alumina and
iron oxide .
2)
Hydration of cement : The chemical reaction that take place between
cement and water is referred as hydration of cement.
Heat of hydration : The reaction of cement with water is
exothermic. The reaction liberates a considerable quantity of heat . This
liberation of heat is called heat of hydration .
3)
Classification of aggregate according to size
are –
I.
Fine aggregate
II.
Coarse aggregate
III.
All – in – aggregate
IV.
Single size aggregate
Classification of aggregater according to shape –
I.
Rounded aggregate
II.
Irregular aggregate
III.
Angular aggregate
IV.
Flaky and Elongate aggregate
4)
Functions of admixture :
I.
To accelerate the initial set of concrete .
II.
To retard the initial set of concrete.
III.
To enhance the workability .
IV.
To improve the penetration and pumpability of
concrete .
V.
To reduce the segregation in grout and concrete
mixtures.
VI.
To increase the strength of concrete.
VII.
To increase the resistance of chemical attack.
VIII.
To reduced the heat of hydration .
IX.
To produced non-skid wearing surfaces.
X.
To increase the bond between old and new
concrete surfaces .
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