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Basic requirement for Soil compaction test

14. July 2017

Typically, tests are conducted in order to figure out the optimal moisture content in the soil. Proctor test and field test are the basic requirements for soil compaction test. These tests are actually carried out to check the maximum density of the soil. We take a good look at some of the basic requirements for soil compaction tests.

Procter test – Proctor test involves collecting a small quantity of soil sample from the jobsite. A standard load is dropped over several repetitions on the sample soil. Finally the soil is weighed and then oven-dried for at least 12 hours to examine the water content. This test is used to determine the maximum density of soil and it also evaluates the effects of moisture on soil density. Soil reference value is indicated as a percentage of density and these values are determined before carrying out any soil compaction process. Modified proctar values are quite high since they consider higher density ranges required for certain construction projects.

Sand Cone Test – A small hole 6×6 inches deep is dug on the job site in order to test the soil compaction. The soil is first removed, weighed and dried and weighed once more to calculate the moisture content. Moisture of the soil is recorded as a percentage for later comparisons. Filling up the dry sand with jar and cone equipment can determine the particular volume of the hole. Dry weight of the removed soil is divided by the amount of sand that is required to fill the hole. It indicates the density of the compacted soil in lbs per cubic foot. Further the acquired density is compared to the earlier obtained maximum procter density that indicates the relative density of the soil that was compacted. 

Nuclear density – Nuclear density test is a relatively rapid and error-free method for calculating the density and moisture content of the soil. The meter makes use of the radio isotope source at the soil surface generally by a backscatter or from a probe directly placed into the soil. The isotope source, cesium 187 gives off photons or gamma rays which are emitted back to the meter detectors at the bottom surface of the unit. Denser soil is likely to absorb more radiation than loose soil and the reading reflects the entire density. This permits recording of water also in a short time.