Civil engineer objective questions – Concrete Technology (Section-7)

151. The top diameter , bottom diameter and the height of a slump mould are

a ) 10 cm , 20 cm , 30 cm

b ) 10 cm , 30 cm , 20 cm

c ) 20 cm , 10 cm , 30 cm

d ) 20 cm , 30 cm , 10 cm

152. In a mix if a desired slump is not obtained , the adjustment for each concrete slump is made by adjusting water content by

a ) 0.25 %

b ) 0.50 %

c ) 0.75 %

d ) 1 %

153. Maximum amount of water content is required if size of the aggregate

a ) round

b ) angular

c ) irregular

d ) none of the above

154. Pick up the incorrect statement from the following :

a ) the bottom and top ends of slump mould are parallel to each other

b ) the axis of the mould is perpendicular to the end faces

c ) the internal surface of the mould is kept clean and free from set cement

d ) the mould is in the form of a frustum of hexagonal pyramid

155. Slump test of concrete is a measure of its

a ) consistency

b ) compressive strength

c ) tensile strength

d ) impact value

156. The amount of slump depends on

a ) workability

b ) aggregate

c ) sand

d ) none of the above

157. In slump test , each layer of concrete compacted by a steel rod 60 cm long and 16 mm diameter for

a ) 20 times

b ) 25 times

c ) 30 times

d ) 40 times

158.  If the slump of concrete mix is 60 mm , its workability is

a ) very low

b ) low

c ) medium

d ) high

159. The concrete having a slump of 6.5 cm , is said to be

a ) dry

b ) earth moist

c ) semi – plastic

d ) plastic

160. Slump test is the most widely used field test primarily because

a ) it indicates the behaviour of fresh concrete under action of gravitational forces

b ) of the simplicity of apparatus and test procedure

c ) it measures consistency or wetness of mix

d ) it ensures uniformity among different batches of similar concrete

161. The workability of concrete by slump test is expressed as

b ) mm² / h

a ) mm³ / h

c ) mm / h

d ) mm

162. The slump for beam slab is

a ) 75-150 mm

b ) 15-30 mm

c ) 50-100 mm

d ) all of the above

163.  The workability may be defined as the amount of applied work required to compact the concrete to its maximum density . The principle is used in

a ) Vee Bee test

b ) slump test

d ) flow test

c ) compaction factor test

164 , When water cement ratio is increased ; workability

b ) decreases

d ) none of the above

a ) increases

c ) both ( a ) and ( b ) of above

165. A concrete is said to be workable if

a ) it is of uniform colour

b ) it is almost a fluid

c ) it can be easily mixed , placed and compacted

d ) it has a tendency to segregate and bleed

166. Workability of concrete in which low water cement ratio is determined by

a ) tensile strength test

c ) compaction factor test

b ) slump test

d ) flexural strength test

167. Wp and Wf are the weights of a cylinder containing partially compacted and fully compacted concrete . If the compaction factor is 0.95 , the workability of concrete is

a ) extremely low

b ) very low

c ) low

d ) high

168. Pick up the correct statement from the following :

a ) segregation is necessary for a workable concrete

b ) consistency does not affect the workability of concrete

c ) if the slump increases , workability decreases

d ) if the concrete mix is dry , the slump is maximum

e ) none of the above

169. Proper proportioning of concrete , ensures

a ) desired strength and workability

b ) desired durability

c ) water tightness of the structure

d ) resistance to wear

e ) all of the above

170. As the grade of concrete increases the quantity of cement required per cubic metre

a ) increases

b ) decreases

c ) constant

d ) all of the above

171. The grade of concrete M150 means that compressive strength of a 15 cm cube after 28 days , is

a ) 100 kg / cm²

b ) 150 kg / cm²

c ) 200 kg / cm²

d ) 250 kg / cm²

172. A joint positioned so as to separate concrete from adjacent surfaces or into in dividual structural elements that are not in direct physical contact , is known as

a ) contraction joint

b ) expansion joint

c ) construction joint

d ) isolation joint

173. If the engineer – in – charge approves , the 10 cm cubes may be used for the work test of concrete provided maximum nominal size of aggregate , does not exceed

a ) 10 mm

b ) 15 mm

c ) 20 mm

d ) 25 mm

174. Pick up the incorrect statement from the following . While performing preliminary test on concrete

a ) proportions of the material and water should be the same as to be used at the work site

b ) cement should be mixed by hand in order to maintain uniformity

c ) concrete mix should be stored in air – tight containers

d ) concrete ingredients should be kept at a temperature of 37⁰ ± 2 ° C

175. For preparing a test – specimen , it is necessary

a ) to mix cement and fine aggregate by dry hand

b ) to mix coarse aggregates

c ) to mix water to the cement , fine aggregates and coarse aggregates

d ) to oil inter surface of the mould and the base plate , before placing concrete

e)  all of the above