State any four factors affecting compaction with their effect.
Following the different factors affecting compaction of soil with their effect:
Water content :
When water content is less i.e. dry soil , compaction is not better , but when water content is excessive , compaction is not possible. Therefore water content should be optimum to get better degree of compaction.
Amount of compaction:
When amount of compaction is more , one can achieve better degree of compaction in soil even with less water content . but when amount of compaction is less , we cannot get MDD even at OMC.
Types of soil :
For the same compactive effort, the MDD of cohesion less soil is more at less OMC. But MDD of cohesive soil is less even at high OMC.
Methods of soil compaction:
When compaction is done manually using rolling, ramming or tamping, then soil gets partially compacted but due to mechanical compaction using various compaction equipment like rollers, vibrators etc. soil can be compacted to higher density.
Use of admixtures :
The compaction of soil can be increased by adding suitable admixtures like lime, fly ash, bitumen, rise husk ash etc. these admixture densify the soil by increasing bonding between soil particles.
Thickness of soil layer –
When thickness of soil layer to be compacted is more, then it is difficult to achieve better compaction. Hence lesser thickness of soil layers can be effectively compacted to required density.