Calculator for water content of soil by oven drying method

Water content of soil by oven drying method

Determination of Water content of soil solids by oven drying method

Aim:

To determine the water content of soil solids by Oven Drying method. The water content (ω) of a soil sample is equal to the mass of water divided by the mass of solids.

Specification:

This test is done as per IS: 2720 (Part II)-1973. The soil specimen should be representative of the soil mass. The quantity of the specimen taken would depend upon the gradation and the maximum size of the particles. For more than 90% of the particles passing through 425 micron IS sieve, the minimum quantity is 25g.

Equipments Required:

• Non-corrodible airtight containers.
• Balance weighting to accuracy of 0.04% of the weight of the soil taken for test.
• Desiccators with suitable desiccating agent.
• Thermostatically controlled oven to maintain temperature 110^oC ± 5^oC.
• Other accessories.

Theory:

In almost all soil tests natural moisture content of the soil is to be determined. The knowledge of the natural moisture content is essential in all studies of soil mechanics. To sight a few, natural moisture content is used in determining the bearing capacity and settlement. The natural moisture content will give an idea of the state of soil in the field. Water content, ω of a soil mass is defined as the ratio of mass of water in the voids to the mass of solids.Equation for specific gravity, ω is

\[\omega = \frac{{\left( {\mathop W\nolimits_2 - \mathop W\nolimits_3 } \right)}}{{\left( {\mathop W\nolimits_3 - \mathop W\nolimits_1 } \right)}} \times 100\% \]

Where,

• W₁ = Weight of empty container in grams.
• W₂ = Weight of container + wet soil in grams.
• W₃ = Weight of container + dry soil in grams.

Note: This method is recommended for coarse and fine grained soils

Precautions:

• Ensure that soil samples are between 350 to 400g. Larger samples take too long to dry, while smaller samples lead to inaccurate results.
• Ensure that the oven temperature is maintained at 110º C ± 5º C. Do not allow the oven door to stay open for too long, as it takes a while for the oven to regain the drying temperature.
• Do not put moist samples in the oven on a shelf below dry samples. Moist samples should be placed on the top shelf and all partially dried samples placed on the lower shelf.
• Do not over-load the oven, as this will create a much longer drying time.
• Do not allow dried samples to pick up moisture after they are removed from the oven. Weigh them immediately after drying.
• Soils and aggregates may contain bacteria and/or organisms which can be harmful for one's health. Wearing dust masks and protective gloves when handling materials is advised. The use of heat resistant gloves/mitts or pot holders to remove samples from the ovens is recommended.
• Prior to handling oven, testing or disposing of any waste materials, students are required to read do's and don'ts of the Geotechnical engineering laboratory.

Procedure:

1. Clean the container with lid and find the mass (W₁ in gm).
2. Select the required quantity of moist soil sample, place it in the container, place the lid on it, and weigh it (W₂ in gm).
3. Keep the container in the oven with lid removed and dry it for at least 24 hr. at a temperature of 110 ^oC till the mass remains constant.
4. Remove the container from the oven, replace the lid, and cool it in desiccators. Find the mass (W₃ in gm).
5. Determine the water constant w by using the above equation.
6. Repeat the experiment with other test samples.

Table:

Sl.No	Particulars	Test No.1	Test No.2	Test No.3
1.	Weight of empty container (W1), gm
2.	Weight of container + wet soil (W2), gm
3.	Weight of container + dry soil (W3), gm
4.	Water content, ω
5.	Average ω = (ω1+ω2+ω3)/3

Result:

Average, ω=

Verification/ Validation:

Soil mass is generally a three phase system. It consists of solid particles, liquid and gas. The phase system may be expressed in SI units either in terms of massvolume or weight volume relationships. Water content value is 0% for dry soil and its magnitude can exceed 100%.

Conclusion:

The experiment is conducted as per the procedure laid down. The water content of the soil sample is determined. Water content, w = _____%. The value is verified and the three phase system is sketched.

Viva Questions:

1. Water content is also called ?
2. Which method is mostly used to determine the water content in field ?
3. What is water content for clay soil ?
4. On which factor water content is depended ?
5. Ground Penetrating Radar (GPR) method is also used for measuring water content (True or False) ?
6. Name different types of soil textures ?
7. The percentage of water remaining in an air-dry soil is called _____________.
8. Draw the schematic diagram of the three phase system based on the result.
9. Is there a possibility of the soil getting burnt? In that case, what will be effect on the water content value ?
10. How does air-dry soil differ from oven-dry soil ?
11. Is this method the most direct method to compute the water content of soil ?
12. To get accurate result, how much gram of soil have you taken to conduct the test ?

Determination of Water content of soil solids by oven drying method

Aim:

To determine the water content of soil solids by Oven Drying method. The water content (ω) of a soil sample is equal to the mass of water divided by the mass of solids.

Specification:

This test is done as per IS: 2720 (Part II)-1973. The soil specimen should be representative of the soil mass. The quantity of the specimen taken would depend upon the gradation and the maximum size of the particles. For more than 90% of the particles passing through 425 micron IS sieve, the minimum quantity is 25g.

Equipments Required:

• Non-corrodible airtight containers.
• Balance weighting to accuracy of 0.04% of the weight of the soil taken for test.
• Desiccators with suitable desiccating agent.
• Thermostatically controlled oven to maintain temperature 110^oC ± 5^oC.
• Other accessories.

Theory:

In almost all soil tests natural moisture content of the soil is to be determined. The knowledge of the natural moisture content is essential in all studies of soil mechanics. To sight a few, natural moisture content is used in determining the bearing capacity and settlement. The natural moisture content will give an idea of the state of soil in the field. Water content, ω of a soil mass is defined as the ratio of mass of water in the voids to the mass of solids.Equation for specific gravity, ω is

\[\omega = \frac{{\left( {\mathop W\nolimits_2 - \mathop W\nolimits_3 } \right)}}{{\left( {\mathop W\nolimits_3 - \mathop W\nolimits_1 } \right)}} \times 100\% \]

Where,

• W₁ = Weight of empty container in grams.
• W₂ = Weight of container + wet soil in grams.
• W₃ = Weight of container + dry soil in grams.

Note: This method is recommended for coarse and fine grained soils

Precautions:

• Ensure that soil samples are between 350 to 400g. Larger samples take too long to dry, while smaller samples lead to inaccurate results.
• Ensure that the oven temperature is maintained at 110º C ± 5º C. Do not allow the oven door to stay open for too long, as it takes a while for the oven to regain the drying temperature.
• Do not put moist samples in the oven on a shelf below dry samples. Moist samples should be placed on the top shelf and all partially dried samples placed on the lower shelf.
• Do not over-load the oven, as this will create a much longer drying time.
• Do not allow dried samples to pick up moisture after they are removed from the oven. Weigh them immediately after drying.
• Soils and aggregates may contain bacteria and/or organisms which can be harmful for one's health. Wearing dust masks and protective gloves when handling materials is advised. The use of heat resistant gloves/mitts or pot holders to remove samples from the ovens is recommended.
• Prior to handling oven, testing or disposing of any waste materials, students are required to read do's and don'ts of the Geotechnical engineering laboratory.

Procedure:

1. Clean the container with lid and find the mass (W₁ in gm).
2. Select the required quantity of moist soil sample, place it in the container, place the lid on it, and weigh it (W₂ in gm).
3. Keep the container in the oven with lid removed and dry it for at least 24 hr. at a temperature of 110 ^oC till the mass remains constant.
4. Remove the container from the oven, replace the lid, and cool it in desiccators. Find the mass (W₃ in gm).
5. Determine the water constant w by using the above equation.
6. Repeat the experiment with other test samples.

Table:

Sl.No	Particulars	Test No.1	Test No.2	Test No.3
1.	Weight of empty container (W1), gm	20.12	20.08	20.00
2.	Weight of container + wet soil (W2), gm	44.12	44.11	46.10
3.	Weight of container + dry soil (W3), gm	41.18	41.16	43.01
4.	Water content, ω
5.	Average ω = (ω1+ω2+ω3)/3

Result:

Average, ω=%

Verification/ Validation:

Soil mass is generally a three phase system. It consists of solid particles, liquid and gas. The phase system may be expressed in SI units either in terms of massvolume or weight volume relationships. Water content value is 0% for dry soil and its magnitude can exceed 100%.

Conclusion:

The experiment is conducted as per the procedure laid down. The water content of the soil sample is determined. Water content, ω =%. The value is verified and the three phase system is sketched.

1. First video

2. Second video

3. Third video

4. Fourth video

Refrence

1. Venkataramaiah, C. (2018). Geotechnical Engineering (6th ed.). New Age International Publishers Pvt Ltd.

2. Punmia, B.C( 2017)Soil mechanics and foundations(17th ed.).Laxmi publications Pvt Ltd.

3. Gopal R, Rao, A, S, R( 2016)Basic and applied Soil mechanics(3rd ed.).New Age International Publishers Pvt Ltd.