148.  Joints in concrete structures, are provided
A. to reduce the tensile stresses likely to be developed due to evaporation of water
B. to minimise the change in the dimensions of the slab
C. to minimise the necessary cracking
D. all the above

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149. The main object of compaction of concrete, is :
A. to eliminate air holes
B. to achieve maximum density
C. to provide initimate contact between the concrete and embedded materials
D. all the above

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150. Too wet concrete may cause
A. weakness of concrete
B. excessive laitance
C. segregation
D. all the above

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151.  Non-uniform compaction may cause the concrete
A. porous
B. non-homogeneous
C. reduced strength
D. all the above

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152.  The compaction of concrete, improves
A. density
B. strength
C. durability
D. all the above

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153. For compacting plain concrete road surface of thickness less than 20 cm, we use
A. internal vibrator
B. screed vibrator
C. form vibrator
D. none of these

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154.  The final operation of finishing floors, is known as
A. screeding
B. floating
C. trowelling
D. finishing

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