DETERMINATION OF FIELD DENSITY OF SOIL BY CORE CUTTER METHOD (IS-27270-PART-29)

Aim

To determine the field density of soil by core cutter method

Reference

IS-2720-Part-29-Determination of dry density of soil in place by the core-cutter method

Apparatus

1. Cylindrical core cutter
2. Steel rammer
3. Steel dolly
4. Balance
5. Steel rule
6. Spade or pickaxe
7. Straight edge
8. Knife

Procedure

1. Measure the height (h) and internal diameter (d) of the core cutter and apply grease to the inside of the core cutter
2. Weigh the empty core cutter (W₁)
3. Clean and level the place where density is to be determined.
4. Drive the core cutter, with a steel dolly on its top, into the soil to its full depth with the help of a steel rammer.
5. Excavate the soil around the cutter with a crow bar and gently lift the cutter without disturbing the soil in it.
6. Trim the top and bottom surfaces of the sample and clean the outside surface of the cutter.
7. Weigh the core cutter with soil (W₂)
8. Remove the soil from the core cutter, using a sample ejector and take representative soil sample from it to determine the moisture content.

Precautions

1. Core cutter method of determining the field density of soil is only suitable for fine grained soil (Silts and clay). This is because collection of undisturbed soil sample from a coarse grained soil is difficult and hence the field properties, including unit weight, cannot be maintained in a core sample
2. Core cutter should be driven into the ground till the steel dolly penetrates into the ground half way only so as to avoid compaction of the soil in the core.
3. Before lifting the core cutter, soil around the cutter should be removed to minimize the disturbances.

Observations and Calculations

Calculate wet unit weight (γ_wet) of the soil using the following relationship

γ_wet = (W₂-W₁)/V

Where,

W₁ = Empty weight of core cutter

W₂ = Weight of core cutter + soil

V = Volume of core cutter (πd²h/4)

D = Inner diameter of core cutter

H = Height of core cutter