|
36. The group index of a soil subgrade is 7. The subgrade soil is rated as |
|
A. fair |
|
B. good |
|
C. very poor |
|
D. poor |
|
Answer: D poor |
||||||||||
|
Higher the value of group index, poorer is the soil as subgrade material.
|
|
37. A contraction joint is provided in concrete pavement to ___. |
|
A. permit cracking at the joint |
|
B. lower the bending moment in the pavement in order to reduce pavement thickness |
|
C. lower the temperature gradient across the depth of the pavement |
|
D. prevent contraction of the pavement |
|
Answer: D prevent contraction of the pavement |
|
The Contraction joints are provided along the transverse direction to prevent the contraction of the pavement and are spaced closer than expansion joints. Load transfer at the joints is provided through the physical interlocking by the aggregates projecting out at the joint faces. |
|
38. In using the data from a plate bearing test for determining the modulus of sub-grade reaction, the value of settlement to be used is ____. |
|
A. 3.75 mm |
|
B. 3.50 mm |
|
C. 2.50 mm |
|
D. 1.25 mm |
|
Answer: D 1.25 mm |
|
The supporting power of subgrade for use in pavement design is evaluated by Plate bearing test using large diameter plates. After applying pressure increments, the consolidation specimen for the plate bearing test is tested without soaking, and a pressure deformation curve is plotted. The deformation of the sample corresponding to pressure required in the plate bearing test to cause a deformation of 0.125 cm. |
|
39. Flexible pavements derive stability primarily from ____. |
|
A. cohesion |
|
B. the binding power of bituminous materials |
|
C. the flexural strength of the surface course |
|
D. aggregate interlock, particle friction and cohesion |
|
Answer: D aggregate interlock, particle friction and cohesion |
|
40. Since the moisture content at the bottom of a rigid pavement slab is generally more than at the top ____. |
|
A. the top of the slab is generally in compression |
|
B. the bottom of the slab is neither is compression nor in tension |
|
C. the bottom of the slab is generally in tension |
|
D. the bottom of the slab is generally in compression |
|
Answer: C the bottom of the slab is generally in tension |
|
As the moisture content at the bottom is more the slab will contract from its natural shape, therefore tensile stress is setup at the bottom of the slab. |