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Proctor test is conducted to identify the compaction of different types of soil at different moisture content.
It is a very important test for structural stability on the construction site.
According to different types of soil & moisture content at the site, we should develop that type of soil samples in the lab and do proctor tests to identify engineering property of that particular soil type.
From this test, we can get OMC & MDD of soil.
Compaction test of soil is carried out using Proctor's test for understanding the compaction characteristics of different soils with change in moisture content. The ability for compacting a soil depends on the water content of the soil. Thus, water acts as a lubricant between the soil grains however as its content increases the water may occupy the entire pores. Since it is relatively incompressible in comparison to the air it may restrict compaction. Proctor compaction test is used to determine the optimum moisture content during compaction which gives the greatest soil density.
importance of proctor compaction test
In this test,
the soil is compacted in the volume of 945-millimeter cube, and the number of layers is 3, and the hammer weight is 2.45 kg, and the height of the fall is 12 inches.
Proctor test is used to find two major properties i.e., optimum moisture content (OMC) and maximum dry density (MDD). It is a field or lab test to perform the compaction of the soil. Proctor test are of two types
1- spt(standard proctor test)- light compaction
2- not(modified proctor test)- heavy compaction.
By performing this test accurately, we can relate to field and lab data.
By finding MDD on field and lab, we are about to know that how much amount of compaction we can achieve on-site/field.
And ultimately, MDD helps in various construction techniques such as earthen dam construction, concrete structures, etc.
In turn, it increases the soil capacity for bearing load.
Standard Proctor test or Proctor compaction test establishes the variation of the unit weight of soil and degree of compaction with the moisture content. It also helps us find out the optimum moisture content for the highest practical density.
When we plot the results of the Standard Proctor test, we observe that the unit weight or density rises initially with increasing moisture, reaches a maximum, and then declines quickly. The maximum is called the maximum unit weight of soil and the moisture content corresponding to it the Optimum Moisture Content (OMC).
The unit weight first increases due to the filling up of voids. Then the soil can’t hold more water without expanding, and the volume starts to increase. This decreases the density first quickly and then slowly when the soil is almost saturated.
