Dry Density of Soil by Core Cutter Method
Cylindrical core cutters of 130mm long and 100mm diameter are used for testing the in-situ compaction of cohesive and clay soils placed as fill. By using core cutter method, bulk density of soil can be quickly calculated and by determining the moisture content of the soil the dry density of the fill can be calculated and hence the voids percentage. A high percentage of voids indicates poor compaction of soil.
A cylindrical core cutter is a seamless steel tube. For determination of the dry density of the soil, the cutter is pressed into the soil mass so that it is filled with the soil without disturbing the core contents. The cutter filled with the soil is lifted up. The mass of the soil in the cutter is determined. The dry density is obtained as
M= mass of the wet soil in the cutter
V= internal volume of the cutter
w= water content.
Equipment for Core Cutter Method
- Cylindrical core cutter, 100mm internal diameter and 130mm long
- Steel rammer, mass 9 kg, overall length with the foot and staff about 900mm.
- Steel dolley, 25mm high and 100 mm internal diameter
- Weighing balance, accuracy 1g.
- Palette knife
- Straight edge, steel rule etc
Procedure of Core Cutter Method
- Determine the internal diameter and height of the core cutter to the nearest 0.25mm
- Determine the mass (M1) of the cutter to the nearest gram.
- Expose a small area of the soil to be tested. Level the surface, about 300mm square in area.
- Place the dolley over the top of the core cutter and press the core cutter into the soil mass using the rammer. Stop the pressing when about 15mm of the dolley protrudes above the soil surface.
- Remove the soil surrounding the core cutter, and take out the core cutter. Soil soil would project from the lower end of the cutter.
- Remove the dolley. Trim the tip and bottom surface of the core cutter carefully using a straight edge.
- Weigh the core cutter filled with the soil to the nearest gram (M2).
- Remove the core of the soil from the cutter. Take a representative sample for the water content determination.
- Determine the water content.
Observation and calculations
|Sl. No.||Observations and Calculations||Determination No.|
|1||Core cutter No.|
|4||Mass of empty core cutter (M1)|
|5||Mass of core cutter with soils (M2)|
|6||M=M2 – M1|
|7||Volume of cutter V|
|9||Dry density using formula|
Results of Core Cutter Method
Dry density of the soil= ________g/ml.