Lab Report #1:
Plastic Particle Size Analysis of Soils
Abstract
This experiment examined the particle-size distribution of soil using Sieve Analysis Method and Hydrometer Analysis Method. The experiment was to determine the percentage passing in each sieve using Sieve Analysis and the percentage finer in suspension using Hydrometer Analysis. Two hundred-fifty gram sample were obtained from a pile of air-dried soil. The sample was sieved through a series of sieves with varying opening sizes and measured the mass retained in each sieve. The soil particles that passed through the sieve with smallest opening were in suspension in a Sodium Hexametaphosphate solution at a given time and percentage finer is calculated. Results are plotted in a semilogarithmic graph and showed that it is relatively well graded because its uniformity coefficient lied within the set range.
Submitted by: Chrislene D. Calivo Groupmates:
Romil Cahatol Arlish Carpio
Ramil Diaz Mark David Siervo
Niki Jon Tolentino
Date Performed: 22 November 2010 Date Submitted: 03 December 2010
I. Objectives
• To determine the particle size distribution of the soil sample by Sieve Analysis and Hydrometer Analysis
• To be able plot and analyze the gradation curve of the soil sample
I. Materials • Balance • Sieves (Nos. 4, 8, 16, 30, 40, 50, 100, 200) • Bottom pan • Lid • Oven • Stirring rod • Hydrometer (type 152H) • Graduated cylinder • Graduated beaker • Sodium Hexametaphosphate • Distilled water • Thermometer • Timer I. Methodology
A. Sieve Analysis
B. Hydrometer Analysis
I. Data and Results A. Sieve Analysis Sieve No. Mass of Sieve (kg) Sieve with Soil (kg) Mass of Soil (kg) % Retained % Cumulative Retained % Cumulative Passing 4 0.499 0.523 0.024 9.60% 9.60% 90.40% 8 0.475 0.503 0.028 11.20% 20.80% 79.20% 16 0.432 0.462 0.03 12.05% 32.85% 67.15% 30 0.405 0.442 0.037 14.80% 47.65% 52.35% 40 0.383 0.41 0.027 10.84% 58.49% 41.51% 50 0.367 0.391 0.024 9.60% 68.09% 31.91% 100 0.337 0.376 0.039 15.66% 83.75% 16.25% 200 0.334 0.361 0.027 10.80% 94.55% 5.45% pan 0.368 0.381 0.013 5.20% 99.75% 0.25% Sum (kg) 0.249 Orig. Mass (kg) Differenc e %
0.250 0.001 40.00%
Table 1. Mass Retained, Percentage Retained and Percentage Passing Using Sieve Analysis
Sieve Diameter (mm) % Cumulative Passing
4.75 90.40% 2.36 79.20% 1.18 67.15% 0.6 52.35% 0.42 41.51% 0.3 31.91% 0.15 16.25% 0.075 5.45% 0.25%
Table 2. Sieve Diameter and % Cumulative Passing Using Sieve Analysis
Mass of Soil=Mass of Sieve with Soil-Mass of Sieve Mass of Soil=0.523 kg-0.499 kg=0.024 kg
% Retained=Mass ofSoilTotal Mass*100% % Retained=0.0240.249*100%=9.64% % Cumulative=94.78%+5.22%=100% % Cumulative Passing=100%-%Cumulative % Cumulative Passing=100%-9.64%=90.36% Error=Orig.Mass-SumOrig.Mass*100% Error= 0.250-0.2490.250*100%=0.40%
B. Hydrometer Analysis
Time elapsed, T (min) Actual Hydrometer Reading Trial 1 Trial 2 Average
0.067 50 40 45 0.25 48 52 50 0.50 47 50 48.5 1.00 47 50 48.5 1.50 46 50 48 2.00 46 50 48
Table 3. Hydrometer reading during the first two minutes
T (min) Actual Hydrome ter Reading Composi te Correctio n Hydrometer Reading Correction Temp (°C) *Effective Hydromet er Length, L (cm) K* Diameter (mm) % finer 0 0.067 45 0 45 27 8.9 0.01258 0.145352 18 0.25 50 0 50 27 8.1 0.01258 0.071607 20 0.50 48.5 0 48.5 27 8.35 0.01258 0.051409 19. 4 1.00 48.5 0 48.5 27 8.35 0.01258 0.036352 19. 4 1.50 48 0 48 27 8.4 0.01258 0.02977 19. 2 2.00 48 0 48 27 8.4 0.01258 0.025781 19. 2 5.00 49 0 49 27 8.3 0.01258 0.016208 19. 6 15.00 49 0 49 27 8.3 0.01258 0.009358 19. 6 30.00 49 0 49 27 8.3 0.01258 0.006617 19. 6 60.00 47 0 47 27 8.6 0.01258 0.004763 18. 8 1440. 00 47 0 47 27 8.6 0.01258 0.000972 18. 8 Table 4. Diameter and percentage finer in suspension of soil particles less than 0.075 mm in
*L, K obtained from the table, specific gravity is assumed to be 2.65, since Hydrometers are calibrated for soils that have a specific gravity of 2.65. (Fundamentals of Geotechnical Engineering 3rd Ed. by Das, p.29)
Graph 2. Particle Diameter (mm) vs. % Finer in suspension
Graph 3. Particle Distribution using Sieve Analysis, superimposed Particle Distribution Using Hydrometer Analysis
Dmm=KLT Dmm=KLT
D mm=0.01258*8.90.067= 0.145352 P=RhαW x 100%
P=8.9*1.0250 x 100%= 3.56% I. Analysis and Discussion
Table 1 is the result of the sieve analysis. As computed, the percent difference of the initial mass from the mass after sieving was just 0.40%. It means that the results are
acceptable.
Table 3 is the hydrometer reading done in the two first two minutes of reading.
Table 4 is the summary of the results for the hydrometer analysis of soil. The mass of the air-dried soil was 13 g, while the oven-dried was 11 g. The composite correction was computed by subtracting one from the calibration reading. But we were not able to calibrate the hydrometer therefore assuming that the composite correction is zero. For the diameter and percent finer, G1 was set to be 1 and Gs was set to be 2.65.
Graph 3 was the combined gradation/particle size distribution curve using hydrometer analysis and hydrometer analysis of soils.
II. Conclusion
There are three basic parameters in analyzing the particle size distribution of soils, namely: Effective size, Coefficient of uniformity and coefficient of gradation. Via Dplot, an application, D10, D30 and D60 were obtained which are necessary in computing for the values of the three parameters. D10, D30, and D60 were found to be 0.101 mm, 0.277 mm, and 0.851 mm respectively.
Coefficient of uniformity, Cu=D60D10= 0.8510.101=8.425
Coefficient of gradation, Cc= D302D60D10=0.27720.851(0.101)=0.893 For soil particles to be classified as well graded, its coefficient of uniformity should be greater than 4 for gravel and greater than 6 for sands, and its coefficient of gradation should lie between 1 and 3. Otherwise, it is poorly graded. From above, it can be said that its uniformity coefficient lies within the pre-set range. But its coefficient of gradation failed to do so. Results showed that it is neither well graded nor poor graded. Its particle distribution lies somewhere in between.
But graph 1, using Sieve Analysis showed that there was uniform distribution of size particles over a wide range. While graph 2, using Hydrometer analysis showed a poorly-graded soil particles since majority of those particles were of the same size.
Using graph 3, it can be said that relatively, the sample was well-graded. It just deviated a bit at the hydrometer analysis.
The errors might have come from the non-calibration of the hydrometer. We were not able to correct our reading because of it. And also, we were not able to check if the temperature of the mixture varied while doing the reading. We just assumed that temperature was constant all throughout.
III. References
ASTM D422 Standard Test Method for Particle-Size Analysis of Soils
Biscontin, Giovanna. CVEN365 Introduction to Geotechnical Engineering LABORATORY MANUAL. “Particle Size Analysis of Soils.” Texas A&M University.
