Determination of Dry Density of Soil by Water Displacement Method

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Water displacement test method is used to determine the dry density of soil. It is suitable for evaluating in-place dry density of cohesive soil due to the nature of specimen required.

The soil sample should be trimmed to obtain a regular shape and then coated it to make it impervious to water. After that, the total volume of the waxed specimen is found by determining the volume of water displaced by the specimen.

Apparatus

1. Water displacement apparatus

2. Weighing balance, accuracy 1g.

3. Paraffin wax (density of paraffin (Pp)= 0.91 g/ml).

4. Cutting knife

5. Heater

6. Oven

7. Measuring jar

8. Brush

9. Water content container

Procedure

1. Take the soil specimen. Trim it to a regular shape. Avoid re-entrant corners. Weigh the specimen.
2. Take some paraffin wax and melt it on a heater. Apply a coat of melted paraffin wax to the specimen with a brush. When it has hardened, apply another coat. Take the mass of the waxed specimen (Mt).
3. Fill the water displacement apparatus with water. When the overflow occurs, close the valve.
4. Place a measuring jar below the overflow tube of the apparatus. Open the valve.
5. Immerse the waxed specimen slowly into the water in the apparatus. Water overflows. Collect the overflowed water in the jar. Determine the volume of the water collected (Vt)
6. Take out the waxed specimen from the apparatus. Dry it from outside.
7. Remove the paraffin wax by peeling it off.
8. Cut the specimen into two pieces. Take a representative sample for the water content determination.

Calculations

SI. No.	Observations and Calculations	Determination No.
-	Observation	1	2	3
1	Mass of specimen (M)	-	-	-
2	Mass of waxed specimen (Mt)	-	-	-
3	Volume of waxed specimen by weight displacement (Vt)	-	-	-
Calculations
4	Mass of wax = Mt – M	-	-	-
5	Volume of wax (Vp) = (Mt – M)/ Pp	-	-	-
6	Volume of specimen (V) = Vt – Vp	-	-	-
7	Water content	-	-	-
8	Dry density =(M/V)/(1+w)	-	-	-

Result

Dry density of soil = _______g/ml.