Geotechnical Engineering, Civil Engg, Bhimaji Dashrath Kanawade

1. Experiment No: 06 (C) Date:
DETERMINATION OF FIELD DENSITYBY WATER DISPLACEMENT/ CLOD
METHOD
Object and scope:
To determine the bulk density and dry density of cohesive soil sample.
Reference:
IS: 2720 (part-33) - 1971
Theory:
This method is suitable for cohesive soil from which a natural clod can be obtained.
Equipments:
1) Container about 30 cm diameter and 45 cm high, having an over flow outlet tube fitted in the upper
half.
2) A rubber tube with spring clip, fitted to the overflow outlet tube
3) Balance accurate to 1gm
4) Paraffin wax, of known specific gravity
5) container for water content determination
6) Thermostatically control the oven,105 °C to 110 °C
7) A glass beaker, 500ml capacity
8) cutting knife
9) Heater for melting wax and brush.
Procedure:
1) With the help of knife trim the sample to a more or less regular shape avoiding re-entrant angles.
Find the mass of the sample (M1).
2) With the help of the brush apply one coat of melted wax. When the coat is hardened apply the
second coat. Find the mass of the wax coated sample (M2).
3) A wax coated sample is carefully immersed in a measuring cylinder containing water. The total
displacement of water is observed.
4) Take out the wax-coated sample, dry it from outside and remove the paraffin wax skin. Cut the
sample in to two pieces and keep a representative sample for water content determination
Observation Table:
Sr.
No.
Description Sample-1 Sample-2 Sample-3
(A) Determination of Bulk density
1 Mass of the specimen M1 (gm)
2 Mass of the waxed specimen M2 (gm)
3 Mass of wax coated Mp=M2-M1 (gm)
4 Density of paraffin wax ρp (gm/cm3)
5 Volume of wax coated Vp=Mp/ ρp (ml)
6 Volume of water displaced Vw (ml)

2. Calculation:
Bulk density ρ = M1/V
Dry density ρd = ρ/ (1+ ω)
Dry unit weight γd = 9.81×ρd
Result:
Bulk density of soil =
Dry density of soil =
Use of Field Density determination of soil:
1) The field density or in-place density of natural soil is needed for the determination of bearing
capacity, stability analysis of slope
2) To determine the vertical stresses at any depth below the ground due to over laying soil strata.
3) In compacted soils, the in-place density is needed to check the degree of compaction obtained.
4) In place density of back fills are needed for determining the lateral soil pressures against retaining
structures.
7 Volume of specimen V=Vw -Vp (ml)
8 Bulk density ρ = M1/V (gm/cm3)
9 Bulk unit weight γ = 9.81× ρ (kN/m3)
10 Average Bulk density
(B) Determination of water content
11 Container No.
12 Mass of container m1(gm)
13 Mass of container + wet soil m2(gm)
14 Mass of container +dry soil m3(gm)
15 Water content ‘ω’
16 Dry density of specimen ρd = ρ/ (1+ ω) (gm/cm3)
17 Dry unit weight of specimen γd = 9.81×ρd
(gm/cm3)
18 Average Dry density

3. Fig. Clod Method