drum roller

rubber tyred roller

sheep′s foot roller

vibratory roller

optimum water content increases but maximum dry density decreases

optimum water content decreases but maximum dry density increases

both optimum water content and maximum dry density increase

both optimum water content and maximum dry density decrease[ES 93]

moisture content only

amount of compaction energy only

both moisture content and amount of compaction energy

none of the above

dry of OMC and wet of OMC

wet of OMC and dry of OMC

wet of OMC and wet of OMC

dry of OMC and dry of OMC where OMC is optimum moisture content

Effective cohesion of a soil can never have a negative value.

Effective angle of internal friction for coarse grained soils is rarely below 30°.

Effective angle of internal friction for a soil increases as state of compact-ness increases.

Effective angle of internal friction is a complicated function of mineralogy and clay size content.