Compaction is a process by which soil particles are artificially rearranged into a closer state. This arrangement reduces voids ratio. When voids present in between soil particles are completely filled by water, n it has no air voids. This zero air void condition, corresponds to oretical maximum compaction for any given water content.

When only a relatively small amount of water is present in soil, it is firmly held by electrical forces at surface of soil particles with a high concentration of electrolyte.

The manner of compaction influences strength of soil sample compacted wet of optimum to a certain extent.

Compaction is a process by which soil particles are artificially rearranged and packed toger in a closer state of contact by mechanical means. While, consolidation is natural process of reduction in voids ratio of specimen.

Due to combined action of pressure and kneading makes pneumatic rollers best suitable for cohesion-less sand and gravels and, and on cohesive soils.

The amount of compaction affects maximum dry density and optimum water content of a given soil. The effect of increasing compactive energy results in an increase in maximum dry density and decrease in optimum water content.

The modified compactor test was standardized by American Associates of State highway officials and is known as modified AASHO test.

The energy per volume is,
\(\frac{WhNng}{V} \), and for Heavy compaction test,
W=4.9kg, h=490mm, N=5, n=25 and V=1000 cc.
? E_MPT=4.9*490*5*25/1000
? E_MPT=2944 kJ/m³.

In Dietert test, cylindrical weight falls through a height of 2 inches. In Standard Proctor test, height of free fall is 12 inches and for Modified Proctor test, height of free fall is 18 inches.

Compaction is a process by which soil particles are artificially rearranged into a closer state which reduces voids ratio and hence re is decrease in porosity. Due to this, dry density of soil sample is increased.