Civil engineer objective questions – Concrete Technology (Section-12)

276. The dimension of a 35 litre of forma for measuring aggregates by volume , are

a ) length 30 cm , breadth 25 cm , height 30 cm

b ) length 39 cm , breadth 25 cm , height 32 cm

c ) length 27 cm , breadth 27 cm , height 48 cm

d ) length 220 cm , breadth 25 cm , height 40 cm

277. In case of hand mixing of concrete , the extra cement to be added is

a ) 5 %

b ) 10 %

c ) 15 %

d ) 20 %

278. The process of mixing , transporting , placing and compacting concrete using Ordinary Portland Cement should not take more than

a ) 30 minutes

b ) 40 minutes

c ) 60 minutes

d ) 75 minutes

279. Placing of concrete should preferably be done at a temperature of

a ) 0 ° C

b ) 10 ° C

c ) 20 ° C

d ) 27 ± 2 ° C

280. To prevent segregation , the maximum vertical height for placing concrete , is

a ) 100 cm

b ) 125 cm

c ) 150 cm

d ) 200 cm

281. For concerting of tunnel linings , transportation of concrete is done by

a ) pans

b ) wheel borrows

c ) containers

d ) pumps

282. Transport of concrete by pumps , is done for a distance of

a ) 100 m

b ) 200 m

c ) 300 m

d) 400 m

283. Tremie ‘ is a

a ) bucket

b ) water – tight pipe

c ) bag

d ) prepack concrete

284. Pick up the correct statement from the following :

a ) the diameter of the pipe line used for transportation of concrete by pumps does not exceed 30 cm

b ) the slump of the concrete to be pumped should not be less that 5 cm and more

c ) the water cement ratio of concrete to be pumped is kept between 0.5 to 0.65 .

d ) number of bends provided in the pipe line should be minimum all of the above

285. Concrete is unsuitable for compaction by vibrator if it is

a ) dry

b ) earth moist

c ) semi – plastic

d ) plastic

286. While compacting the concrete by a mechanical vibrator , the slump should not exceed

a) 2.5 cm

b ) 5.0 cm

c) 7.5 cm

d ) 10 cm

287. Compaction of mechanical vibrations is suitable for

a ) all the grades of concrete

b ) all the structural elements

c ) all the mixes except very plastic mixes

d ) all of the above

288. Surface vibrator is effective only when the thickness of concrete member does not exceed

a ) 100 mm

b ) 150 mm

c ) 200 mm

d ) 250 mm

289. A surface vibrator for compaction of concrete is preferred for all of the following except

a ) reft footings

b) column

c ) RCC slab

d) pavement

290. Curing

a ) reduces the shrinkage of concrete

b ) preserves the properties of concrete

c ) prevents the loss of water by evaporation

d ) all of the above

291 , The process by which fresh cement concrete is wetted by rain water is known as

a ) curing

b ) wetting

c ) raining

d ) none of the above

292. The process of hardening the concrete by keeping its surface moist is known as

a ) placing

b ) wetting

c ) curing

d ) compacting

293. Generally curing is allowed only after concreting of

a ) 24 hours

b ) 7 days

c ) fully set

d ) none of the above

294. Steam curing is used in

a ) columns only

b ) long slabs and column

c ) mass production of precast concrete

d ) all of the above

295. Steam curing is not used with

a ) ordinary portland cement

b ) high alumina cement

c ) rapid hardening cement

d ) all of the above

296. Curing of pavements , floors , roofs and slabs is done by

a ) membrane method

b ) ponding method

c ) covering surface with bags

d ) sprinkling water method

297. Curing period is minimum for concrete using

a ) ordinary portland cement

b ) high alumina cement

c ) rapid hardening cement

d ) all of the above

298. Curing of concrete for long period ensures better

a ) strength

b ) wear resistance

c ) water tightness and durability

d ) all of the above

299. Under normal conditions using an ordinary cement , the period of removal of the form work is

a ) 7 days for beams soffits

b ) 14 days for bottom of slabs of spans 4.6 m and more

c ) 21 days for bottom of beams over 6m spans

d ) 2 days for vertical sides of columns

e ) all of the above

300. Pick up the correct statement from the following :

a ) water enables chemical reaction to take place with cement

b ) water lubricates the mixture of gravel , sand and cement

c ) only a small quantity of water is required for hydration of cement

d ) strength of concrete structure largely depends upon its workability

e ) all of the above

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