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191.

Which of the following statement is correct?

A.	Harshness in concrete mix increases if finer aggregates to fill the voids in coarse aggregates are less.	B.	As the internal friction of aggregates increases, the workability of concrete decreases.
C.	As the slump value increases, the workability of concrete also increases.	D.	all of the above

192.

More water should not be added in the concrete mix, as to increase

A.	strength	B.	durability
C.	water-cement ratio	D.	all of these

193.

The main object of proportioning concrete is to obtain

A.	required strength and workability	B.	desired durability
C.	water tightness	D.	all of these

194.

As per IS : 459-1978, the concrete mixes are designated into

A.	4 grades	B.	5 grades
C.	6 grades	D.	7 grades

195.

Which of the following grade is not recommended by IS 456-1978?

A.	M 10	B.	M 20
C.	M 40	D.	M 55

196.

The concrete mix of grade M 25 means that the compressive strength of 15 cm cubes at 28 days after mixing is

A.	15 N/mm2	B.	20 N/mm2
C.	25 N/mm2	D.	30 N/mm2

197.

The test conducted in the laboratory on the specimen made out of trial concrete mix is called

A.	preliminary test	B.	slump test
C.	works test	D.	none of these

198.

In performing preliminary test

A.	the moulds requred for test specimens should be rigid	B.	the mxi should be stored in air=tight containers
C.	the aggregates should be dry	D.	all of the above

199.

In order to prepare a test specimen, it is necessary to

A.	mix the cement and fine aggregate (sand) by dry hand	B.	mix the coarse aggregate
C.	mix water to the cment, fine aggregate and coarse aggregates	D.	all of the above

200.

The ratio of different ingredients (cement, sand and aggregate) in concrete mix of grade M 20 is

A.	1 ; 1 : 2	B.	1 ; 1.5 : 3
C.	1 ; 2 : 4	D.	1 ; 3 : 6