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
