Objective Question & Answer

Statement i is correct: In rigid pavements, providing a high-quality base/sub-base course acts

as a filter layer that prevents fine subgrade particles from mixing with water and being ejected

through joints under heavy wheel loads (mud-pumping).

Statement ii is correct: A thick sub-base layer protects the frost-susceptible subgrade layer

underneath by acting as an insulation barrier against frost action and heaving.

Statement iv is correct: In flexible pavements, the main function of the granular base and sub

base layers is to distribute the wheel load over a wider area, reducing the stress reaching the

weaker subgrade layer.