Concrete Technology

1

Placing of concrete should preferably be done at a temperature of

A. ` 0^circ C`
B. ` 10^circ C`
C. ` 20^circ C`
D. `23^circ C`
E. `27 pm 2^circ C`

2

 

For the construction of the retaining structures, the type of concrete mix to be used, is

A. 1 : 3 : 6
B. 1 : 2 : 4
C. ` 1 : 1 1/2` : 3
D. 1 : 1 : 2
E. 1 : 4 : 8

3
 

Pick up the incorrect statement from the following:

.
A. Tricalcium silicate (`C_ 3 S`) hydrates rapidly
B. Tricalcium silicate (`C_3 S`) generates more heat of hydration
C. Tricalcium silicate (`C_3 S`) develops early strength
D. Tricalcium silicate (`C_3 S`) has more resistance to sulphate attack
E. None of these.

4

If X, Y and Z are the fineness modulli of coarse, fine and combined aggregates, the percentage (P) of fine aggregates to combined aggregates, is

A. ` P = (Z - X)/(Z - Y) xx 100`
B. ` P = (X - Z)/(Z - Y) xx 100`
C. ` P = (X - Z)/(Z + Y) xx 100`
D. ` P = (X + Z)/(Z - Y) xx 100`
E. ` P = (Z - X)/(Y - Z) xx 100`

5

Wp and Wf are the weights of a cylinder containing partially compacted and fully compacted concrete. If the compaction factor `(W_p/W_f)`  is 0.95, the workability of concrete is

A. extremely low
B. very low
C. low
D. high
E. none of these.