# All About Determination of Specific Gravity of Soil ( Pycnometer Method ) : Calculator

The specific gravity of soil is a crucial factor in geotechnical engineering, as it determines the density and strength of the soil. Thus, accurately determining the specific gravity is essential for the design and analysis of various construction projects. One of the most widely used methods for determining the specific gravity of soil is the Pycnometer Method, which utilizes a specialized instrument called a pycnometer. In this article, we will discuss the Pycnometer Method in detail and how it can be performed using a calculator to obtain precise and reliable results. So, let’s delve into the world of soil mechanics and discover all about the determination of specific gravity of soil with the Pycnometer Method.

## Determination of Specific Gravity of Soil ( Pycnometer Method ) : Calculator

Introduction:

Specific gravity is an important parameter to determine the properties of soil. It is the ratio of the weight of a given volume of soil solids to the weight of the same volume of water at a specified temperature. The specific gravity of soil depends on the mineral composition and pore space of the soil particles. There are different methods to determine the specific gravity of soil, one of which is the Pycnometer Method. This method involves using a Pycnometer, a specialized laboratory instrument, to determine the specific gravity of soil.

Pycnometer Method:

The Pycnometer Method is a simple and accurate method to determine the specific gravity of soil. It involves measuring the weight of a known volume of soil solids and the weight of the same volume of water at a given temperature. The specific gravity is then calculated using the following formula:

Specific gravity = (Weight of soil / Weight of water) / (Volume of soil / Volume of water)

Equipment Required:

1. Pycnometer: It is a glass container with a ground-glass stopper and a capillary tube attached to the stopper.

2. Balance: An accurate balance with a resolution of at least 0.1 g is needed to measure the weights of soil and water.

3. Oven: An oven is required to dry the soil samples before the test.

4. Thermometer: A thermometer is needed to measure the temperature of the water.

Procedure:

1. Weigh an empty and dry Pycnometer (W1) and record its weight.

2. Fill the Pycnometer with distilled water at the desired temperature and weigh it (W2).

3. Place the Pycnometer in the oven and heat it to 105oC -110oC for 24 hours.

4. Take out the Pycnometer from the oven and allow it to cool to the desired temperature.

5. Take a soil sample and dry it in the oven at 105oC -110oC for 24 hours.

6. Take the dry soil sample and place it in the Pycnometer. Add distilled water till it is completely filled.

7. Attach the capillary tube to the Pycnometer and record the weight (W3).

8. Mix the soil and water thoroughly by shaking the Pycnometer and ensure there are no air bubbles.

9. Allow the Pycnometer to stand for 24 hours to allow any entrapped air bubbles to escape.

10. Weigh the Pycnometer with the soil and water (W4).

11. Record the temperature of the water (t).

Calculations:

Volume of soil (V1) = W3 – W1

Volume of water (V2) = W4 – W2

Specific gravity = W3 – W1 / (W4 – W2)

/(V1 / V2)

Specific gravity = (W3 – W1) / (W4 – W2) / (V1 / V2)

/(1 + (t x 0.00021))

Where,

t = temperature of water in oC

0.00021 = coefficient of volumetric expansion of water

Benefits of using a calculator:

The process of calculating the specific gravity of soil using the Pycnometer Method requires several steps and involves multiple calculations. Using a calculator makes the process faster and more accurate. A calculator also allows for easy conversion of units

## Conclusion

In conclusion, the determination of specific gravity of soil using the pycnometer method is a crucial process in soil testing and engineering. It helps to determine the density and composition of soil, which plays a significant role in analyzing its properties and behavior. The use of a reliable and accurate calculator in this method ensures precise and efficient results. With the advancements in technology, there are now various online calculators available, making the determination of specific gravity of soil more convenient and accessible. Understanding the pycnometer method and using the calculator correctly can aid in achieving accurate and reliable results, thus contributing to better decision making in various construction and agricultural projects.