Civil engineer objective questions – Concrete Technology (Section-8)

176. Minimum number of test specimens required for finding the compressive strength of concrete are

a ) 3

b ) 5

c ) 6

d ) 9

177. The preliminary test is repeated if the difference of compressive strength of three test specimens , exceeds

a ) 8 kg / cm

b ) 10 kg / cm

c ) 12 kg / cm²

d ) 15 kg / cm²

178. For the construction of R.C.C. slabs , columns , beams , walls , etc. the grade of concrete mix used , is

a ) 1 : 3 : 6

b ) 1 : 1 : 3

c ) 1 : 2 : 4

d ) 1 : 1 : 2

179. For the construction of the concrete mix to be used , is :

a ) 1 : 3 : 6

b ) 1 : 1 : 3

d ) 1 : 1 : 2

c ) 1 : 2 : 4

180. The correct proportion of ingredients of concrete , depends upon

a ) bulking of sand

b) water content

c ) absorption

d) workability

e ) all of the above

181. If the depth of moist sand in a cylinder is 15 cm and the depth of the sand with fully inundated with water is 12 cm , the bulking of the moist sand , is

a ) 10 %

b) 15%

c ) 20 %

d) 25%

182. Pick up the correct statement from the following :

a ) the quality of water governs the strength of concrete

b ) the quality of water required for concreting , depends upon the grading of aggregate and method of compaction

c ) 10 % excess of water reduces the strength of concrete by 15 %

d ) 30 % excess of water reduces the strength of concrete by 50 %

e ) all of the above

183. For preparing ordinary concrete , the quantity of water used , is

a ) 5 % by weight of aggregates plus 20 % of weight of cement

b ) 10 % by weight of aggregates the plus 10 % of weight of cement .

c ) 5 % by weight of aggregates plus of 30 % weight of cement

d ) 30 % by weight of aggregates plus 10 % of weight of cement

184. The following proportion of the ingredients or concrete mix , is not in confirmation to arbitrary method of proportioning

a ) 1 : 1 : 2

b ) 1 : 2 : 4

c ) 1 : 3 : 6

d ) 1 : 4 : 10

186. If P , Y and Z are the weights of cement , fine aggregates and coarse aggregates respectively and W / C is the water to be added to first batch , is obtained by the equation

a ) 0.1p + 0.3 y + 0.1z – w / c x p

b ) 0.3p + 0.1y + 0.012z = w / c x p

c ) 0.4p + 0.2y + 0.01z = w / c x p

d ) 0.5p + 0.3y + 0.012 = w / e x p

187 . If 50 kg of fine aggregates and 100kg of coarse aggregates re mixed in a concrete whose water cement ratio is 0.6 , t he weight of water required for harsh mix , is

a ) 8 kg

b ) 10 kg

d ) 14 kg

c ) 12 kg

188. The method of voids for determination of quantity of cement paste assumes that

a ) voids in coarse aggregates are filled by fine aggregates

b ) voids in fine aggregates are filled by the cement paste

c ) volume of fine aggregates is equal to total voids in coarse aggregate plus 10 % extra

d ) volume of cement paste required is equal to total volume of voids in fine aggregates plus 15 % extra

e ) all of the above

189. Pick up the incorrect statement from the following

a ) workability of the concrete mix decreases with an increase in the moisture content

b ) concrete for which preliminary tests are conducted , is called controlled concrete

c ) bulking of sand depends upon the finesse of grains

d ) concrete mix 1 : 6 : 12 , is used for mass concrete in piers

e ) all of the above

190. Shrinkage in cement concrete can be reduced by using

a ) low water cement ratio

b ) less cement in the concrete

c ) proper concrete mix

d ) pre – saturated aggregates

e ) all of the above

191. Shrinkage in cement concrete is directly proportional to

a ) water content in the mix

b ) sand content

c ) aggregate content

d ) aggregate to cement ratio

192. Shrinkage in cement concrete is directly proportional to

a ) cement content

b ) sand content

c ) aggregate content

d ) temp . of water

193. Shrinkage in cement concrete decrease with

a ) initiation of load

b ) removal of load

c ) removal of moisture

d ) addition of moisture

194. The shrinkage of concrete is due to change in

a ) length

b ) cross – sectional area

d ) surface area

c ) volume

195. The concrete shrinkage is more pronounced in

a ) rich mix

b ) lean mix

c ) very lean mix

d ) normal mix

196. Maximum shrinkage takes place in cement concrete after

a ) 28 days

b ) three month

c ) six month

d ) one year

197. Poisson’s ratio of concrete reduced by using

a ) richer mix

b ) poor mix

c ) constant with any mix

d ) all of the above

198. Poisson’s ratio for concrete ranges between

a ) 0.11 to 0.21

b ) 0.20 and 0.25

c ) 0.25 and 0.30

d ) 0.30 and 0.35

199. As compared to static tests the dynamic tests on concrete give

a ) higher value of poisson’s ratio

b ) lower value of poisson’s ratio

c ) same value of  poisson’s ratio

d) none of the above

200. The 28 days cube strength of mass concrete using aggregates of maximum size 5 cm for gravity dams should be

a) between 150 to 300 kg/cm sq.

b) between 350 to 600 kg/cm sq.

c) between 150 to 500 kg/cm sq.

d) below 200  kg/cm sq.