Calculator for specific gravity of soil by density bottle method

calculator for specific gravity of soil by density bottle method

Density bottle method

Determination of specific gravity of soil solids by density bottle method

Aim:

To determine the specific gravity of soil solids by Density bottle method. Specific gravity G is defined as the ratio of the weight of an equal volume of distilled water at that temperature, both weights taken in air.

Specification:

IS 2720 (Part III)-1980 is the standard recommended to determine specific gravity of fine grained soils. The value ranges are same as the previous experiment. The average of the values obtained shall be taken as the specific gravity of the soil particles and shall be reported to the nearest 0.01 precision. If the two results differ by more than 0.03 the tests shall be repeated.

Equipments Required:

  • 50 ml capacity density bottle with stopper.
  • A constant temperature water bath (27oC).
  • Oven with a range of 105 to 110oC.
  • Vacuum desiccators.
  • Vacuum pump.
  • Other accessories, such as, weighing balance accurate to 0.001 g, trays, wooden mallet, etc.

Theory:

Specific gravity of soil solids is defined as the weight of soil solids to weight of equal volume of water. Equation for specific gravity, G:

\[G = \frac{{\left( {\mathop W\nolimits_2 - \mathop W\nolimits_1 } \right)}}{{\left( {\mathop W\nolimits_2 - \mathop W\nolimits_1 } \right) - \left( {\mathop W\nolimits_3 - \mathop W\nolimits_4 } \right)}}\]

Where,
  • W1=weight of density bottle in grams.
  • W2=weight of density bottle + dry soil in grams.
  • W3=weight of density bottle + soil+ water grams.
  • W4=weight of density bottle + water grams.
Note: This method is normally used for fine-grained soils. The method may also be used for medium and coarse grained soils, if the coarse particles are grained to pass 4.75-mm IS sieve before using.

Precautions:

  • Soil grains whose specific gravity is to be determined should be completely dry. If on drying soil lumps are formed, they should be broken to its original size.
  • Inaccuracies in weighing and failure to completely eliminate the entrapped air are the main sources of error. Both should be avoided.
  • While cleaning the glass jar, please be careful as there may be glass grains projecting out and it may tear the skin.
  • Make sure, you handle the glass jar and conical cap without falling on your legs or floor. Hence, handle the equipment with care.

Procedure:

  1. Clean and dry the density bottle and weigh it along with the stopper (W1 in gm).
  2. Select about 25 gm of dry soil free of clods and put the same into the density bottle. Weigh it with brass cap and washer (W2 in gm).
  3. Fill the density bottle with de-aired water upto half its height and stir the mix with a glass rod. Add more water and stir it. Place the stopper on top and take the weight (W3 in gm).
  4. Remove all the contents from the density bottle, clean it thoroughly and fill it with distilled water. Weigh it (W4 in gm).
  5. Now use the above equation for determining G.
  6. Repeat the same process for additional tests.

Table:

Sl.No Particulars Test No.1 Test No.2 Test No.3
1. Weight of density bottle (W1), g
2. Weight of density + dry soil (W2), g
3. Weight of density + soil + water (W3), g
4. Weight of density + water (W4), g
5. Calculation of specific gravity, G
6. Average G = (G1+G2+G3)/3

Result:

AVERAGE G=

Verification/ Validation:

The value of specific gravity for the existing soil falls in the range 2.6 to 2.75. Select the type of soil with refrence to specific gravity as shown in table.If there is any variation, check under the specification provided and re-do the experiment to get accurate results.

Soil types Specific gravity
Clean sands and gravel 2.65-2.68
Silt and silty sands 2.66-2.70
Inorganic clays 2.70-2.80
Soil with high mica,Iron 2.75-2.85
Organic soil May fall below 2.0

Conclusion:

The experiment is conducted as per the procedure laid down. The specific gravity of soil solids = _________. The value falls in the range 2.6 to 2.75. Hence, the type of soil is _____ as per the specification.

Viva Questions:

  1. Which method is accurate in determining specific gravity of soil solids ?
  2. What are the steps involved in determining specific gravity using density bottle method ?
  3. How much grams of soil need to be taken for the test ?
  4. What is the specification required for the test ?
  5. What is the equation to determine the specific gravity ?
  6. Can we use kerosene instead of water to determine specific gravity of soil ?
  7. Could we do classification of soil based on the specific gravity of soil ?
  8. Could there be entrapped air in the soil sample ?
  9. What are the various sources of error in this experiment, if any ?
  10. What are the applications in geotechnical engineering where the specific gravity is used ?

Determination of specific gravity of soil solids by density bottle method

Aim:

To determine the specific gravity of soil solids by Density bottle method. Specific gravity G is defined as the ratio of the weight of an equal volume of distilled water at that temperature, both weights taken in air.

Specification:

IS 2720 (Part III)-1980 is the standard recommended to determine specific gravity of fine grained soils. The value ranges are same as the previous experiment. The average of the values obtained shall be taken as the specific gravity of the soil particles and shall be reported to the nearest 0.01 precision. If the two results differ by more than 0.03 the tests shall be repeated.

Equipments Required:

  • 50 ml capacity density bottle with stopper.
  • A constant temperature water bath (27oC).
  • Oven with a range of 105 to 110oC.
  • Vacuum desiccators.
  • Vacuum pump.
  • Other accessories, such as, weighing balance accurate to 0.001 g, trays, wooden mallet, etc.

Theory:

Specific gravity of soil solids is defined as the weight of soil solids to weight of equal volume of water. Equation for specific gravity, G:

\[G = \frac{{\left( {\mathop W\nolimits_2 - \mathop W\nolimits_1 } \right)}}{{\left( {\mathop W\nolimits_2 - \mathop W\nolimits_1 } \right) - \left( {\mathop W\nolimits_3 - \mathop W\nolimits_4 } \right)}}\]

Where,
  • W1=weight of density bottle in grams.
  • W2=weight of density bottle + dry soil in grams.
  • W3=weight of density bottle + soil+ water grams.
  • W4=weight of density bottle + water grams.
Note: This method is normally used for fine-grained soils. The method may also be used for medium and coarse grained soils, if the coarse particles are grained to pass 4.75-mm IS sieve before using.

Precautions:

  • Soil grains whose specific gravity is to be determined should be completely dry. If on drying soil lumps are formed, they should be broken to its original size.
  • Inaccuracies in weighing and failure to completely eliminate the entrapped air are the main sources of error. Both should be avoided.
  • While cleaning the glass jar, please be careful as there may be glass grains projecting out and it may tear the skin.
  • Make sure, you handle the glass jar and conical cap without falling on your legs or floor. Hence, handle the equipment with care.

Procedure:

  1. Clean and dry the density bottle and weigh it along with the stopper (W1 in gm).
  2. Select about 25 gm of dry soil free of clods and put the same into the density bottle. Weigh it with brass cap and washer (W2 in gm).
  3. Fill the density bottle with de-aired water upto half its height and stir the mix with a glass rod. Add more water and stir it. Place the stopper on top and take the weight (W3 in gm).
  4. Remove all the contents from the density bottle, clean it thoroughly and fill it with distilled water. Weigh it (W4 in gm).
  5. Now use the above equation for determining G.
  6. Repeat the same process for additional tests.

Table:

Sl.No Particulars Test No.1 Test No.2 Test No.3
1. Weight of density bottle (W1), g 37.40 54.51 37.40
2. Weight of density + dry soil (W2), g 63.49 74.07 63.49
3. Weight of density + soil + water (W3), g 153.61 165.76 153.61
4. Weight of density + water (W4), g 137.37 153.70 137.37
5. Calculation of specific gravity, G
6. Average G = (G1+G2+G3)/3



Result:

Average, G=

Verification/ Validation:

The value of specific gravity for the existing soil falls in the range 2.6 to 2.75. Select the type of soil with refrence to specific gravity as shown in table.If there is any variation, check under the specification provided and re-do the experiment to get accurate results.

Soil types Specific gravity
Clean sands and gravel 2.65-2.68
Silt and silty sands 2.66-2.70
Inorganic clays 2.70-2.80
Soil with high mica,Iron 2.75-2.85
Organic soil May fall below 2.0

Conclusion:

The experiment is conducted as per the procedure laid down. The specific gravity of soil solids obtained is . This value falls in the range 2.6 to 2.75. Hence, the type of soil is .

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.

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