Determination of grain size distribution of soil by sieve analysis

Determination of grain size distribution of soil by sieve analysis

Name of the Experiment	Determination of grain size distribution of soil by sieve analysis
Theory
Grain size analysis is used in the engineering classification of soils. Particularly coarse grained soils. Part of suitability criteria of soils for road, airfield, levee, dam and other embankment construction is based on the grain size analysis. Information obtained from the grain size analysis can be used to predict soil water movement. Soils are broadly classified as coarse grained soils and fine grained soils. Further classification of coarse grained soils depends mainly on grain size distribution and the fine grained soils are further classified based on their plasticity properties. The grain size distribution of coarse grained soil is studied by conducting sieve analysis.
List of Equipment needed
1. A set of Sieves 4.75 mm, 2.36 mm, 1.18mm, 0.60mm, 0.30 mm 0.15 mm 0.075mm including lid and pan 2. Tray 3. Weighing Balance 4. Oven 5. Sieve Shaker           6. Brush
Procedure
1. Weigh 1000gms of oven dry soil sample, of which grain size distribution has to be studied. 2. Take the soil sample into 75μ sieve. 3. Wash the soil sample keeping it in the sieve. Washing of soil sample means: place the soil in the sieve and gently pour water over the soil so that it wets the soil and remove the fine particles in the form of mud, leaving only the sand and gravel size particles in the sieve. 4. Transfer the soil retained in the sieve after washing into a tray. Invert the sieve into the tray and pour water gently so that all the soil particles retained in the sieve are transferred into the tray. 5. Keep the tray in the oven for 24 hours at 105ºc to dry it completely. 6. Weigh the oven dry soil in the tray (W) 7. The weight of the fine grained soil is equal to 1000 – W 8. Clean the sieve set so that no soil particles were struck in them. 9. Arrange the sieves in order such that coarse sieve is kept at the top and the fine sieve is at the bottom. Place the closed pan below the finest sieve. 10. Take the oven dried soil obtained after washing into the top sieve and keep the lid to close the top sieve. 11. Position the sieves set in the sieve shaker and sieve the sample for a period of 10 minutes. 12. Separate the sieves and weigh carefully the amount of soil retained on each sieve, This is usually done by transferring the soil retained on each sieve on a separate sieve of paper and weighing the soil with the paper. 13. Enter the observations in the Table and calculate the cumulative percentage of soil retained on each sieve. 14. Draw the grain size distribution curve between grain size on log scale on the abscissa and the percentage finer on the ordinate. Plot the graph between percentage finer and logarithmic grain size (mm).From the graph, obtain the percentage of course, medium and fine sands.
Observation and Tabulation
S.No Aperture size of sieve in mm Weight of soil retained (gm) % Weight Retained Cumulative Percentage Retained Percentage Finer 1 4.75mm 2 2.36mm 3 1.18mm 4 0.600mm 5 0.300mm 6 0.150mm 7 0.075mm
Calculation
Uniformity coefficientCu = D60 / D10 Coefficient of CurvatureCc = D30 2 / (D60 X D10)
Result and Discussion
Percentage of gravel (>4.75mm) = Percentage of coarse sand (4.75mm – 2.00 mm) = Percentage of medium sand (2.00mm – 0.425 mm) = Percentage of fine sand (0.425mm – 0.0.075 mm) = Percentage of fines (<0.075 mm) = Uniformity Coefficient Cu = Coefficient of Curvature Cc =