Size Distribution of a Coarse-Grained Soil-Free-Sample for Students

Question: Required to determine the particle size distribution of a coarse-grained soil (Soil 1) by carrying out a sieve analysis and a sedimentation test (hydrometer analysis). The results obtain from these tests are then used to classify Soil 1 according to the Unified Soil Classification System (USCS). Answer: Introduction The main purpose of this experiment was to find the particle size distribution for a coarse-grained soil. The main experiment which was carried out to determine this was sieve analysis and sedimentation test (hydrometer analysis). The results achieved were later used to categorize the soil which was done according to the UCSC category. Procedure There were two experiments whereby the first the one was for particle size determination. The following procedure was done Soil sample of about 200 gm was first weighed The arrangement of the sieves was done in descending order of their aperture that is the 4.75mm, 2.36mm, 1.18mm, 600um, 300um, 150um and 75um. The soil sample was then sieved and masses retained on each sieve was weighed and recorded. The finer sample was used for the sedimentation test. The following procedure was carried out. In this experiment, a hydrometer scale which measures the quantity in g/l was used. In this experiment the cylinder was filled with distilled water. Then the hydrometer was inserted and the correction meniscus reading Cm was recorded. Also, the water temperature was measured. Then the milk shake container was used whereby 20g of fine grained soil was added then distilled water was added to full and recorded as Mo. the mixture was shaken for about two minutes using a milk shaker. Then the content in the milk shaker was poured into a 1000ml cylinder. Any fine remains in the milk shaker were washed with distilled water. Then the water was added to craft the mixture 1000 ml. A stopper was placed on top of the cylinder and then the cylinder was turned upside down for about 5 times. After shaking the content, it was placed on a table and the hydrometer was used to take the readings at different intervals. The readings were taken at 30sec, 1min, 2min, and 4 minutes. The hydrometer was taken out after the 4 minute reading and washed with distilled water. It was then used to take a final reading at 8 min. Results Data sheet 1: Sieve Analysis AS Sieve Sieve+sample g (2) Mass retained g (2)-(1) Cumulative mass retained, g % cumulative mass retained % Mass passing Size, mm Weight, g (1) 4.750 427.03 427.06 0.03 0.03 0.014 99.986 2.360 474.65 487.45 12.8 12.83 6.69 93.41 1.180 383.40 419.18 35.18 48.61 23.18 76.82 0.600 347.66 390.86 43.2 91.81 43.78 56.22 0.300 343.40 399.17 55.77 147.58 70.36 29.64 0.150 305.72 318.34 12.62 160.2 76.38 23.62 0.075 290.22 293.93 3.71 163.81 78.15 21.85 Pan 265.70 300.84 35.14 199.05 94.90 5.10 Datasheet 3: Hydrometer Test The following was sample description achieved. The mass in the suspension, Mo (g) = 21.6 The specific unit weight of the soil Gs = 2.65 Normal temperature = 26oC Recorded Time (min) t Recorded Hydrometer reading (g/l) Rh Meniscus corrected hydrometer reading (g/l) Rh Temperature (oC) Corrected hydrometer reading Rc F1 F2 F3 0.5 15 15 25.3 3.80 14.14 1 14.5 14.5 25.3 2.82 10.00 2 12 12 25.3 3.88 7.07 4 11 11 25.3 3.90 5.00 8 10 10 25.3 3.92 3.54 Conclusion From the experiment, its clear that the soil is well graded. The soil has all categories of the soil in terms of size grading. This can be seen because all the sieves have retained some amount of the sample soil. Therefore through the experiment, the classification of the soil sample in terms of the sizes is done.