19-04-2014, 02:14 PM
DETERMINATION OF FIELD DENSITY (UNIT WEIGHT ) OF SOIL BY SAND REPLACEMENT METHOD
AIM
To determine the field density of soil at a given location by sand replacement method.
APPARATUS
1. Sand pouring Cylinder
2. Calibrating can
3. Metal tray with a central hole
4. Dry sand (Passing through 600 micron sieve )
5. Balance
6. Metal tray
7. Scraper tool
8. Glass plate
THEORY AND APPLICATIONS
In core cutter method the unit weight of soil obtained from direct measurement of weight and volume
of soil obtained from field. Particularly for sandy soils the core cutter method is not possible. In such
situations the sand replacement method is employed to determine the unit weight. In sand
replacement method a small cylindrical pit is excavated and the weight of the soil excavated from the
pit is measured. Sand, whose density is known, is filled into the pit. By measuring the weight of sand
required to fill the pit and knowing the density of soil , volume of the pit is calculated .Knowing the
weight of soil excavated from the pit and the volume of pit the density of soil is calculated. Therefore
in this experiment there are two stages (1) Calibration of sand density and (2) Measurement of soil
density.
PROCEDURE
CALIBRATION OF SAND DENSITY
1. Measure the internal dimensions diameter (d) and height (h) of the calibrating can and
compute its internal volume V.
2. Fill the sand pouring cylinder (SPC) with sand with 1 cm top clearance to avoid any spillover
during operation and find its weight (W1)
3. Place the SPC on a glass plate, open the slit above the cone by operating the valve and allow
the sand to run down. The sand will freely run down till it fills the conical portion. When there
is no further downward movement of sand in the SPC, close the slit.
4. Find the weight of the SPC along with the sand remaining after filling the cone (W2)
5. Place the SPC concentrically on top of the calibrating can.Open theslit to allow the sand to
rundown until the sand flow stops by itself.This operationwill fill the calibrating can and the
conical portion of the SOC.Now close theslit and find the weight of the SPC with the
remaining sand(W3)
RESULT
1. Dry unit weight of the soil
2. Wet unit weight of the soil
3. Void ratio of the soil
4. Porosity of the soil
5. Degree of saturation