Concrete Technology and Design

181. Proper proportioning of concrete, ensures

1. Desired strength and workability
2. Desired durability
3. Water tightness of the structure
4. All the above

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182. Ratio of permissible stress in direct compression and bending compression is

1. Less than 1
2. Between 1 and 1.5
3. Between 1.5 and 2.0
4. Greater than 2

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183. Sand generally contains salt if it is obtained from:

1. Nala beds
2. River beds
3. Sea beds
4. None of these

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184. Sand requiring a high water cement ratio, belongs to

1. Zone I
2. Zone II
3. Zone III
4. Zone IV

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185. Sands of zone I are:

1. Course
2. Medium
3. Medium to fine
4. Fine

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186. Saw dust can be rendered chemically inert by boiling it in water containing

1. Ferrous sulphate
2. Potassium chloride
3. Ammonia
4. Nitric acid

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187. Segregation is responsible for

1. Honey-combed concrete
2. Porous layers in concrete
3. Surface scaling in concrete
4. All the above

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188. Select the correct statement

1. Elastic modulus of high tensile steel is nearly the same as that of mild steel
2. Elastic modulus of high tensile steel is more than that of mild steel
3. Carbon percentage in high carbon steel is less than that in mild steel
4. High tensile steel is cheaper than mild steel

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189. Select the incorrect statement

1. The loss of pre-stress is more in pre-tensioning system than in post-tensioning system.
2. Pre-tensioning system has greater certainty about its durability.
3. For heavy loads and large spans in buildings or bridges, post-tensioning system is cheaper than pre-tensioning system
4. None of the above

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190. Separation of coarse aggregates from mortar during transportation, is known

1. Bleeding
2. Creeping
3. Segregation
4. Shrinkage

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