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56. An important purpose of prime coats is to ___. |
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A. promote the bond between the subbase course and the subgrade |
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B. promote the bond between the base and the wearing courses |
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C. increases the stability of the subgrade |
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D. promote the adhesion between an existing wearing surface and a subsequent wearing surface |
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Answer: D promote the adhesion between an existing wearing surface and a subsequent wearing surface |
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Explanation: The main objective of priming is to plug in the capillary voids of the loose mineral particles on the existing surface using a binder of low viscosity. The binder can penetrate into voids and promote the adhesion between existing wearing surface and subsequent wearing surface. Bituminous prime coat is the first application of low viscosity liquid bituminous material over an existing porous or absorbent pavement surface like the WBM base course. |
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57. One of the probable causes of rutting on flexible pavements is ___. |
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A. inadequate compaction of pavement layers |
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B. high wind speeds |
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C. excessive stripping of binder material from the wearing course |
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D. use of flaky aggregates in the wearing course |
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Answer: A inadequate compaction of pavement layers |
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58. Mud pumping is commonly associated with ___. |
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A. premixed bituminous construction |
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B. cement concrete pavement on clay subgrade |
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C. cement concrete pavement on granular subgrade |
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D. bituminous penetration macadam construction |
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Answer: B cement concrete pavement on clay subgrade |
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Explanation: When the soil slurry ejects out through the joints and cracks of cement concrete pavement caused during the downward movement of slab under the heavy wheel loads, is known as Mud pumping. It is noticed just after the rains in cement concrete pavements that are placed on clayey soil subgrade. |
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59. Alligator or map cracking is the common type of failure in ____. |
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A. bituminous surfacing |
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B. concrete pavements |
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C. gravel roads |
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D. WBM construction |
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Answer: A bituminous surfacing |
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Alligator or map cracking is: · Most common type of failure · Occurs due to relative movement of pavement layer materials · Most common in bituminous surfacing |
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60. Road roughness is measured using ____. |
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A. Benkelman beam |
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B. Falling weight deflectormeter |
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C. Dynamic cone penetrometer |
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D. Bump integrator |
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Answer: D Bump integrator |