The water displacement test method is utilized for determining the dry density of soil. This method is particularly applicable for evaluating the in-place dry density of cohesive soil, owing to the required nature of the specimen. To begin the testing process, the soil sample is trimmed to achieve a regular shape. Next, the specimen is coated to make it impervious to water. Once the specimen is properly coated, the total volume of the waxed specimen is determined by measuring the volume of water that is displaced by the specimen.
Apparatus
The equipment required for this experiment includes a water displacement apparatus, a weighing balance with an accuracy of 1g, paraffin wax with a density of 0.91 g/ml, a cutting knife, a heater, an oven, a measuring jar, a brush, and a water content container.
The water displacement apparatus is used to measure the volume of the wax samples, while the weighing balance is used to measure their mass with a precision of 1g. The paraffin wax is the substance being tested, and its density is known to be 0.91 g/ml. The cutting knife is used to shape the wax samples, while the heater is used to melt the wax. The oven is used to dry the wax samples after they have been heated, and the measuring jar is used to measure the volume of water displaced by the wax samples.
A brush is also needed to clean the equipment between trials, and a water content container is used to measure the water content of the wax samples. By using this equipment and following the appropriate procedures, it is possible to accurately measure the water content of the wax samples.
Procedure
To determine the water content in a soil specimen, it is necessary to follow a series of steps. Firstly, the specimen must be trimmed into a regular shape, avoiding any re-entrant corners, and then weighed. To prepare the specimen for the water content test, a coat of melted paraffin wax is applied using a brush, which is allowed to harden before another coat is applied. The mass of the waxed specimen (Mt) is then recorded.
Next, a water displacement apparatus is filled with water until the overflow occurs, and the valve is closed. A measuring jar is placed beneath the overflow tube, and the valve is opened. The waxed specimen is then slowly immersed into the water, causing water to overflow, which is collected in the jar. The volume of the water collected (Vt) is determined, and the waxed specimen is removed from the apparatus and dried from the outside.
To complete the water content determination, the paraffin wax is peeled off, and the specimen is cut into two pieces. A representative sample is taken from the soil 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.