Civil engineer objective questions – Concrete Technology (Section-15)

351. The minimum clear horizontal spacing between groups of cables or ducts of grouped cables shall be greater of

a ) 30 mm or 5 mm more than maximum size of aggregate

b ) 40 mm or 5 mm more than maximum size of aggregate

c ) 30 mm or maximum size of aggregate

d ) 40 mm or maximum size of aggregate

352. The minimum clear vertical spacing between groups of cables or ducts of grouped cables shall be

a ) 30 mm

b ) 40 mm

c ) 50 mm

d ) none of the above

353. The grouting of ducts in post – tensioned prestressed concrete causes

a ) reduction in deflections

b ) reduction in crack width

c ) reduction in corrosion

d ) all of the above

354. A parabolic tendon in prestressed beam causes an equivalent balancing

a ) concentrated shear force

b ) constant moment

c ) distributed force

d ) uniformly distributed force

355. An increase in strain in a concrete member at constant stress is called

a ) creep loss

b ) relaxation

c ) shrinkage

d ) transfer stress

356. Strain in concrete at zero stress is called

a ) creep loss

 b ) relaxation

c ) shrinkage

d ) transfer stress

357. In case of prestressed concrete , prestressing force is

a ) tensile force

b ) compressive force

c ) shear force

d ) momentum force

358. In case of prestressed concrete

a ) load carrying capacity of member increases

b ) quantity of concrete is saved for same grade

c ) quantity of steel is saved for same grade

d ) all of the above

359. Light weight concrete is prepared by

a ) using light aggregate

b ) formation of air void in concrete by omitting sand

c ) formation of air voids in cement paste by the substances causing foam

d ) all of the above

360. Light weight concrete is used in

a ) heat resistance

b ) air conditioning of buildings

c ) non load bearing wall

d ) reducing thickness

361. To obtain a light weight concrete the types of aggregate used is

a ) granite

b ) magnetite

c ) barite

d ) pumice

362. A concrete in which dry coarse aggregate are first packed to have the least voids and then the cement sand mortar is injected under pressure to fill all the voids , resulting in a very dense concrete , is known as

a ) pre – packed concrete

b ) vacuum concrete

c ) no fines concrete

d ) aerated concrete

363. The ferrocement is a composite material obtained by

a ) random disposal of short , discontinuous fibres in the conventional concrete

b ) reinforcing the cement mortar with steel fibres in the form of wire mesh

c ) blending ferrous compounds in the ordinary Portland cement

d ) all of the above

364. The cement sand ratio in the ferrocement matrix should not be leaner than

a ) 1 : 1.5

b ) 1 : 2

c ) 1 : 2.5

d ) 1 : 3

365. The volume of reinforcement in ferrocement ( percent ) normally varies between

a ) 1-2

b) 2-5

c ) 5-8

d) 8-10

366. The water cement ratio for ferrocement mix should be

a ) less than 0.35

b ) between 0.35 to 0.40

c ) between 0.40 to 0.45

d ) between 0.45 to 0.60

 367. What is the process of smoothening the surface of newly placed concrete with a trowel called ?

a ) hardening

b ) knocking up

c ) flashing

d ) floating

368. If water cement ratio is more ,

a ) the durability of the concrete will be more

b ) the durability of the concrete will be less

c ) the durability of the concrete will not be affected

d ) none of the above

369. Low water – cement ratio in concrete :

a ) reduces the permeability of concrete

b ) increases the compressive strength

c ) improves the frost resistance of concrete

d ) all of the above

370. To get ultra high strength concrete ,

a ) compaction by pressure and helical binding

b ) polymerization in concrete

c ) reactive powder concrete

d ) all of the above

371. As compared to Ordinary Portland Cement , use of pozzolanic

a ) reduces workability

b ) increases bleeding

c ) frustum of a cone cement :

c ) increases shrinkage

d ) increases strength

372 , Steel mould used for slump test is in the form of :

a ) cube

b ) cylinder

c) frustum of a cone

d ) triangular

373. The interval for which the cement products remain in plastic condition is known as ::

a ) reaction time

b ) hardening time

c ) curing time

d ) setting time

374. The compressive strength of an ordinary Portland cement ( 1 : 3 :: Cement : sand ) after seven days test should not be less than :

a ) 115 kg / cm2

b ) 175 kg / cm²

c ) 220 kg / cm²

d ) 275 kg / cm²

375. The concrete in which preliminary tests are preformed for designing the mix is called :

a ) ordinary concrete

b ) rich concrete

c ) controlled concrete

d ) lean concrete

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