Civil engineer objective questions – Concrete Technology (Section-11)

251 , Workability of concrete may be improved by adding

a) air entering agent

b ) foaming agent

c) oily agent

d ) aluminium compound

e) all of the above

252. Workability of concrete is directly proportional to

a ) grading of the aggregate

b ) time of transit

c ) aggregate cement ratio

d ) none of the above

253. Workability of concrete is inversely proportional to

a ) grading of the aggregate

b ) time of transit

c ) aggregate cement ratio

d ) none of the above

254. The shrinkage of concrete

a ) is proportional to water content in the mix

b ) is proportional to cement concrete

c ) increases with age of concrete

d ) all of the above

255. Addition of pozzolana to cement causes

a ) reduction in permeability

b ) loss of heat of hydration

c) reduction in bleeding

d ) increase in curing time

e ) all of the above

256. For a good concrete

a ) aggregates should be hard and durable

b ) cement should be sufficient to produce the required strength

c ) water should be free form organic material

d ) mixing of ingredients should be done thoroughly so as to produce homogeneity

e ) all of the above

257. For the construction of RCC slab , column , beam and walls , the minimum grade of concrete mixed is used for

a ) 1 : 3 : 6

b ) 1 : 1 : 2

c ) 1 : 1.5 : 3

d ) 1 : 2 : 4

258. M100 grade of concrete approximates

a ) 1 : 3 : 6

b ) 1 : 1 : 2

c ) 1 : 2 : 4

d ) 1 : 1.5 : 3

259. M150 grade of concrete approximates

a ) 1 : 3 : 6

b ) 1 : 1 : 2

c ) 1 : 2 : 4

 d ) 1 : 1.5 : 3

260. Strength of concrete with passage of time

a ) increases

b ) decreases

c ) fluctuates

d ) remains constants

261. Concrete gains strength due to

a ) chemical reaction of cement with sand and coarse aggregates

b ) evaporation of water from concrete

c ) hydration of cement

d ) all of the above

262. The nature of fresh concrete is

a ) elastic

b ) plastic

c ) rigid

d ) all of the above

263. Too wet concrete may cause

a ) weakness of concrete

b) excessive laitance

c ) segregation

d) lower density

e ) all of the above

264. The process of proper and accurate measurement of concrete ingredients for uniformity of proportion , is known

a ) grading

b ) curing

c ) mixing

d ) batching

265. Proper batching ensures

a ) economy

b ) durability

c ) workability

d ) strength

e ) all of above

266. Batching error means inaccuracy in the quantity of

b ) cement

a ) aggregates

c ) water

d ) all of the above

267. In the batching of materials , the ingredients should be measured to a tolerance ( as a percentage of batch quantity ) of

a ) ± 1.0

b ) ± 2.0

c ) ± 3.0

d ) ± 4.0

268. The process of mixing some mortar in the mixer at the beginning of the first batch concrete mixing is called

a ) buttering

b ) borrowing

c ) initiating

d ) accelerating

269. During manufacture of concrete minimum period for which mixing is done in mixer for manufactured / crushed aggregate is ( IS 456 : 2000 )

a ) 1 min

b) 1.5 min

c ) 2 min

d) 2.5 min

270. The concrete mixers are normally classified on the basis of

a ) the technique of discharging the mixed concrete

b ) capacity of batch handled

c ) the number of drums

d ) all of the above

271. The capacity of concrete mixer is expressed in terms of

a ) total volume of concrete produced per day

b ) total volu me of concrete produced in 8 hrs

c ) total volume of concrete produced per hr

d ) volume of concrete mix handled per batch

272. The objective of mixing concrete materials are the following except

a ) coat the surface of all aggregate particles with cement paste

b ) blend all the ingredients into a uniform mass

c ) obtain concrete of uniform colour and grading

d ) obtain concrete of desired workability

273. Pick up the correct statement from the following :

a ) The weight of ingredients of concrete mix , is taken in kilograms

b ) water and aggregates is measured in liters

c ) the finished concrete is measured in cubic metres

d ) 20 bags of cement make one tonne

e ) all of the above

274. For batching 1 : 3 : 6 and water cement ratio 0.6 both by weight , the quantity of water required per bag , is

a ) 10 kg

b ) 15 kg

c ) 20 kg

d ) 30 kg

275. For batching 1 : 3 : 6 concrete mix by volume , the ingredients required per bag for 50kg cement are

a ) 70 liters of sand 120 liters of aggregates

b ) 70 kg of sand 140 liters of aggregates

c ) 105 liters of sand and 140 liters of aggregates

d ) 105 liters of sand and 210 liters of aggregates

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