Testing Porosity of Soils (page 2)

Experimental Procedure

1. Fill one measuring cup to the 200 ml mark with sand, the second cup with 200 ml of clay and the third with 200 ml with small pebbles.
2. Fill a graduated cylinder to the 100 ml mark with water.
3. Slowly and carefully pour the water into the first cup until the water just reaches the top of the sand.
4. Pour slowly so none will spill out of the measuring cup, as this will cause an error in the measurement.
5. Record exactly how much water was used.
6. Use the formula below to calculate the percent porosity for the sand.
7. Porosity = (Amount of water added to sample ÷ Total sample volume) x 100
8. Repeat the same procedure with the clay and the pebbles.
9. Record the results in a table similar to the one shown

10. Using graph paper or a computer equipped with Excel^® visually display the data by plotting a line or bar graph comparing the porosity of the various soil types.
11. The numerical values for % porosity are displayed along the Y-axis verses the soil sample names along the X-axis.
12. As a possible extension investigation, after measuring the porosity of sand and clay, make a mixture of these two samples by adding them together. Repeat the water addition procedure and calculate the % porosity then compare the results to that of the two individual soil samples. 

Bibliography

Soil Testing Laboratory Manual and Question Bank, K V S Rao and V C S Rao, Laxmi Publications, ISBN: 8170081378

This book describes the purpose of soil, introduces the different kinds of soil and their properties, and explains what its main component parts are.

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