Experiment No. 7: Soil Compaction
Print this page
First  |  Last  |  Prev  |  Next

Determination of the dry density - moisture content relationship of a soil.

Cylindrical moulds and accessories, Rammer, Sample extruder, Balance (1 g accuracy), 4.75 mm IS sieve, Mixing tray, Trowel, Graduated cylinder, Straight edge knife, Apparatus for moisture content determination.

1. Obtain a sufficient quantity of air-dried soil and pulverize it. Take about 3 kg of soil passing through 4.75 mm sieve in a mixing tray.

2. Weigh the mould with base plate and apply grease lightly on the interior surfaces. Fit the collar and place the mould on a solid base.

3. Add water to the soil to bring its moisture content to about 8% and then mix it thoroughly using the trowel until the soil gets a uniform colour.

4. For light compaction, compact the moist soil in three equal layers using a rammer of mass 2.6 kg and having free fall of 31 cm. Distribute the blows evenly, and apply 25 blows in each layer. Ensure that the last compacted layer extends above the collar joint. Alternatively for heavy compaction, compact the soil with 25 blows per layer, in five equal layers with a rammer of mass 4.9 kg and 45 cm free fall.

5. Rotate the collar so as to remove it, trim off the compacted soil flush with the top of the mould, and weigh the mould with soil and base plate.

6. Extrude the soil from the mould and collect soil samples from the top, middle and bottom parts for water content determination. Place the soil back in the tray, add 2% more water based on the original soil mass, and re-mix as in step 3. Repeat steps 4 and 5 until a peak value of compacted soil mass is reached followed by a few samples of lesser compacted soil masses.

First  |  Last  |  Prev  |  Next