Civil Engineering - Concrete Technology

21. 

Pick up the correct statement from the following:

A. Calcium chloride acts as a retarder
B. Gypsum (calcium sulphate) acts as an accelerator
C. Gypsum (calcium sulphate) acts as a retarder
D. Calcium chloride acts as an accelerator
E. Both (c) and (d).

Answer: Option E

Explanation:

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22. 

Joints in concrete structures, are provided

A. to reduce the tensile stresses likely to be developed due to evaporation of water
B. to minimise the change in the dimensions of the slab
C. to minimise the necessary cracking
D. all the above.

Answer: Option D

Explanation:

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23. 

If the effective working time is 7 hours and per batch time of concrete is 3 minutes, the output of a concrete mixer of 150 litre capacity, is

A. 15, 900 litres
B. 16, 900 litres
C. 17, 900 litres
D. 18, 900 litres

Answer: Option D

Explanation:

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24. 

The condition not applicable to water cement ratio law, is

A. internal moisture conditions on hydration continue till complete strength is gained
B. concrete specimens may be tested at any temperature
C. concrete specimens need be of same age
D. concrete specimens need be of same size
E. none of these.

Answer: Option B

Explanation:

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25. 

High temperature

A. increases the strength of concrete
B. decreases the strength of concrete
C. has no effect on the strength of concrete
D. none of these.

Answer: Option B

Explanation:

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