51. Base course is used in rigid pavements for ___.

A.  prevention of slab cracking

B.  prevention of subgrade settlement

C.  prevention of thermal expansion

D.  prevention of pumping



Answer: D        prevention of pumping


In rigid pavement base course is used to

(i) Prevent pumping (ii) Protect the subgrade against frost action.



52. Dowel bars in concrete pavement are placed ____.

A.  perpendicular to the direction of traffic

B.  along the direction of traffic

C.  can be placed along any direction

D.  along 45° to the direction of traffic



Answer: B         along the direction of traffic



53. Temperature stresses in concrete pavements may cause the slab to crack. If a slab cools uniformly then the crack will develop at the which of the following locations of the slab?

A.  Near edges

B.  At centre

C.  Near edges and at corners

D.  At corners



Answer: B     At centre

The corners and edges are free to contract while cooling. Hence, the cracks due to stresses will develop at the centre of the slab.



54. In the context of flexible pavement design, the ratio of contact pressure to tyre pressure is called the Rigidity Factor. This factor is less than unity when the tyre pressure is ____.

A.  equal to 0.56 N/mm2

B.  more than 0.7 N/mm²

C.  equal to 0.7 N/mm2

D.  less than 0.56 N/mm²



Answer: B     more than 0.7 N/mm²



55. In highway pavements emulsions are mainly used in ____.

A.  patching and maintenance

B.  bitumen macadam

C.  asphaltic concrete

D.  surface dressing



Answer: A         patching and maintenance


Emulsions are used in bituminous road constructions, especially in maintenance and patch repair works. Even if it is raining, emulsion can be used.




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