Experiment No. 8: Soil In-Situ Density
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Determination of the in-situ density of soils by core cutter method or sand replacement method.

Core Cutter Method
Cylindrical core cutter, Dolley, Rammer, Balance (1 g accuracy), Spade, Straight edge knife, Sample extruder, Apparatus for moisture content determination.

1. Measure the internal dimensions of the core cutter and weigh it.

2. Clean and level the site surface where the field density is to be determined.

3. Place the dolley on the cutter and press both into the soil using the rammer until only about 15 mm of the dolley protrudes above the surrounding soil surface.

4. Remove the soil around the cutter with the spade, lift up the cutter, and trim carefully the top and bottom surfaces of the soil sample.

5. Clean the outside surface of the cutter and weigh it with the soil.

6. Remove the soil core from the cutter and take three representative samples in moisture cans for water content determination.

Sand Replacement Method
For hard and gravelly soils, the core-cutter method is not suitable. In its place, sand replacement method can be used, and it involves making a hole in the ground, weighing the excavated soil and determining the volume of the hole.

Sand pouring cylinder, Calibrating cylinder, Clean and dry sand, Metal tray with a central circular hole, Balance (1 g accuracy), Glass plate, Trowel, Scraper tool, Apparatus for moisture content determination.

1. An inverted cone forms the base of the sand pouring cylinder, and a shutter at the cone tip controls the release of sand through a uniform free fall.

2. First determine the bulk density of the sand to be used in the field. For this, measure the internal dimensions of the calibrating cylinder so as to obtain its volume. Fill the pouring cylinder with sand and weigh. Place it concentrically on top of the calibrating cylinder, and allow sand to run out and fill both the calibrating cylinder and the inverted conical portion.

3. To obtain only the mass of sand filling up the conical portion, lift the pouring cylinder and then weigh with remaining sand. Place it on a glass plate, and allow sand to run out. Weigh again the pouring cylinder with left over sand.

4. Calculate the mass of sand that fills up the calibrating cylinder, and from its known volume, work out the bulk density of the sand for the allowed free fall.

5. Clean and level the site surface, and place the square tray with a central hole. Excavate a hole of diameter equal to that of the tray hole and depth equal to about 15 cm. Collect the excavated soil in the tray, weigh and then take representative samples for water content determination.

6. Fill the pouring cylinder with the same sand, place it concentrically over the hole, open the shutter and allow sand to fill up the hole.

7. When there is no further movement of sand, close the shutter, remove the cylinder and weigh it with the remaining sand.

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