Engineering :: Concrete Technology

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261.

The slump whould not exceed 50 mm when compacting concrete with vibrators.

Agree

Disagree

262.

When vibrators are used for compaction, the consistency of concrete depends upon the

A.	type of mix	B.	placing conditions
C.	efficiency of vibrator	D.	all of these

263.

If the slump of the concrete mix is less than 50 mm, then while compacting it with vibratiors, the segregation will not take place.

Right

Wrong

264.

Which of the following statement is correct while compacting concrete with vibrators?

A.	The vibrator should be inserted horizontally.	B.	The vibrator should not be immersed through a full depth of freshly laid concrete.
C.	The vibrator should not touch the form surface.	D.	all of the above

265.

The levelling operation that removes humps and hollows and give a true, uniform concrete surface is called

A.	screeding	B.	floating
C.	trowelling	D.	compacting

266.

The final operation of finishing the concrete surface is called

A.	screeding	B.	floating
C.	trowelling	D.	none of these

267.

The process of removing the irregularities from the surface of concrete left after screeding is called floating.

Correct

Incorrect

268.

Trowelling should be finished on the same day of its laying operation.

Yes

269.

The process of hardening the concrete mixes by keeping its surface moist for a certain period is called

A.	floating	B.	curing
C.	screeding	D.	none of these

270.

The object of curing is to

A.	prevent the loss of water by evaporation	B.	reduce the shrinkage of concrete
C.	preserve the properties of concrete	D.	all of these