295. When a brick is immersed in water for 24 hours and then dried, if
A. no grey or white deposits appear on the surface, the brick is free from soluble salts
B. 10 per cent surface is covered with grey or white deposits, the brick has slight efflorescence
C. 50 per cent surface is covered with grey or white deposits, the brick has serious efflorescence
D. All the above.

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296. Rapid hardening cement contains
A. Tr-calcium silicate
B. Tr-calcium aluminate
C. Tetra-calcium alumino-ferrite
D. Dicalcium silicate.

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297. Name the type of cement from the following for canal linings :
A. sulphate resisting cement
B. rapid hardening cement
C. quick setting cement
D. pozzuolana cement.

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298. Sea sand used in structures causes
A. dampness
B. efflorescence
C. disintegration
D. All of these.

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299. If water required for 1 bag of cement is 30 litres, the water cement ratio is :
A.0.4
B.0.5
C.0.6
D. None of these.

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300. Pick up the correct statement from the following :
A. For thin structures subjected to wetting and drying, the water cement ratio should be 0.45
B. For mass concrete structures subjected to wetting and drying, the water ratio should be 0.55
C. For thin structures which remain continuously under water, the water-cement ratio by weight should be 0.55
D. All the above.

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301. Pick up the correct statement from the following :
A. The theory of formation of concrete is based on the phenomena of formation of voids
B. The bulking of sand is taken into account while volumetric proportioning of the aggregates
C. The dry sand and the sand completely flooded with water, have practically the same volume
D. All the above.

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