Aim
Introduction
Dry sieve analysis also referred to as texture analysis is the process of determining the distribution of particle sizes in a soil sample. The data obtained through this analysis will help in classifying the soil type according to the ANSI, USCS, AASHTO, USDA and other standard systems of classification. The importance of soil classification provides useful information to engineers during construction of buildings and structures. It helps them to determine a particular soil that suits the requirements of the proposed project. In implementing projects such as land cover fills, water filter, roads, foundations, bridges and other projects, one need to know the type of soil and their particle size distribution. This paper analyses the soils particle size distribution after performing dry sieve analysis. The analysis will help in tackling a real life project that needs the same criteria (Abdaal, Jordan and Szilassi, 16)
Apparatus
Mortar and pestle
Sieves (size: 4, 10, 20, 40, 60, 140, 200, bottom pan and lid). For the granular filter material sieves of size: 10, 12, 14, 16, 18, 20, and 25 are used.
Wire sieve brush (for sieves larger than size 60)
Paintbrush (for sieves size 60 and smaller)
Mechanical shaker
Balance accurate to 0.1 grams
Any soil type
Method
Two sieve analysis experiments are to be conducted on the same soil type from the selected area with each soil sample collected to have a weight of approximately 500g.
The clumps in the soil are broken down and weighed. This sample is labelled Wi.
Each sieve is then cleaned, and the weight of each sieve plus the pan is obtained.
The sieves are then stacked in order from size 200, 140 to size 4, and a sample is placed on the top sieve and covered with a lid.
The rest of the sieves are placed in one of the mechanical shakers, and the shaker turned on for not less than 6 minutes.
The sieve with the sample retained after mechanical shaking then weighed.
Steps 1-5 is repeated for the rest of the additional tests required.
The equations are used to fill the table below regarding the results obtained.
Results
The following tables show the results of analysis of the soil test. Some equations below were used to fill the rest of the table concerning the raw data obtained from the experiment.
Sample A
Mass lost = 0.1grams
Equation 1 is used to calculate the percent of mass retained
Rn=WnWts x 100 1
Where,
Rn = % retained on individual sieve
Wn = Mass on individual sieve
Wts = Mass of total sample
Equation 2 is used to calculate the weight the cumulative percent retained on each successive sieve in the 7th column, table 1.
Cumulative % retained = i=1i=nRn . 2
Equation 3 is used calculate the percent finer for the 8th column in Table 1
% finer = 100 - i=1i=nRn 3
In analysis of the total mass lost during analysis, equation 4 is used
Mass lost during analysis (%) = 100(Wi – Wts)/ Wi 4
Where Wi = initial sample massGraph
Equation 5 is used to calculate the coefficient of uniformity in the particle size distribution
Cu = D60/D10 .. 5
Where,
Cu = Coefficient of uniformity
D60 = maximum diameter of particles finer than 60%
D10 = maximum diameter of particles finer than 10%
D60 = 0.9 mm
D10 = 0.08 mm
Therefore, Cu = 0.9/0.08 = 11.25
Equation 6 is used to calculate the coefficient of curvature
Cc =D30 2D60 x D10 . 6
Where,
Cc = Coefficient of curvature
D30 = maximum diameter of particles finer than 30%
D30 = 0.3mm
D60 = 0.9 mm
D10 = 0.08 mm
Therefore, Cc =0.3 20.9 x 0.08 = 1.25
Sample B
Graph
Equation 5 is used to calculate the coefficient of uniformity in the particle size distribution
Cu = D60/D10 .. 5
Where,
Cu = Coefficient of uniformity
D60 = maximum diameter of particles finer than 60%
D10 = maximum diameter of particles finer than 10%
D60 = 0.8mm
D10 = 0.075 mm
Therefore, Cu = 0.8/0.075= 10.67
Equation 6 is used to calculate the coefficient of curvature
Cc =D30 2D60 x D10 . 6
Where,
Cc = Coefficient of curvature
D30 = maximum diameter of particles finer than 30%
D30 = 0.25mm
D60 = 0.8 mm
D10 = 0.075 mm
Therefore, Cc =0.2520.8 x 0.075 = 1.042
(Abdaal, Jordan and Szilassi, 23)
Discussion
According to the two tests carried out above, it is clear that the two soil sample has close property values that include the coefficient of uniformity and curvature. This shows some high degree of accuracy of the experimental performance. A soil sample is well graded if the coefficient of uniformity is above 4 to 6. It is poorly graded when Cu is less than 4. A well-graded soil should have a Cu more than 4 and Cc in the range of 1 to 3. This means the soil has a range of particles. According to ANSI/AWWA standard, the coefficient of uniformity of soil above is suitable for use in the construction of subgrade for roads. This is because the soils particles are varying and some seepage is allowed in the road construction. Another testing method that can validate the compatibility of the soil to its purpose is the use of hydrometer analysis method. This method is used to determine the grain size distribution of fine-grained soils (45th Anniversary of the Journal, 23).
The client is advised to use the soils from the area for the filter design. This is because the soil has varied particles size and as such they can allow filtration. Also, with D60 = 0.8 mm and D10 = 0.075 mm, the soils shows to have a variety of particles in it (Engineeringcivil.com, 1).
Conclusion
Dry sieve testing involved a mechanical process of determining, and classifying properties of the course grained soils such as coefficient of uniformity. The process was done carefully using two soil samples, and the results were plotted in a graph for comparison. The soils samples proved to possess closely related values of coefficient of uniformity and coefficient of curvature. However, further experiments on the same will yield more accurate values. The experiment was done, and results were within the expectation limit according to ANSI/AWWA, AASHTO, and USCS, USDA standards.
Work cited
Abdaal, A., G. Jordan, and P. Szilassi. "Testing Contamination Risk Assessment Methods for Mine Waste Sites". Water, Air, & Soil Pollution 224.2 (2013): n. pag. Web.
Engineeringcivil.com, "Various Lab Test on Soil". N.p., 2011. Web. 22 Feb. 2016.
"45Th Anniversary of The Journal "Soil Mechanics And Foundation Engineering" ("SMFE")". Soil Mechanics and Foundation Engineering 41.1 (2004): 1-3. Web.
Appendix
USACE EM-1110-2-1906 Appendix V [3]
ASTM D421 [7]
