Lab Report 1 Particle Size Analysis of S PDF

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Lab Report #1: Particle Size Analysis of Soils

Abstract Particle size analysis for soils is performed in order to determine the percentage of different grain sizes contained within a soil sample in accordance to ASTM D422. After the experiment, this report concludes that the soil sample that was analyzed is uniformly distributed after it passed the Unified Soil Grading Criteria. The errors in the experiment performed are assumed negligible because of the small discrepancy in the results of the two trials performed.

Submitted by: Nur-Ranji Jajurie

Group Mates: Prince Intal Vanessa Gale Marie Natividad Joshua Rebutiaco Xerxes Tupag

Date Performed: February 10, 2016 Date Submitted: May 09, 2016 1

I.

Objectives 

To acquire the particle size distribution of the soil sample in accordance to ASTM D422: Standard Test Method for Particle-Size Analysis of Soils



To produce data with acceptable error of less than 2%



To generate a semi-logarithmic plot that displays the particle size distribution of the soil and to identify the grading of the soil using the data points on the graph.

II.

III.

Materials 

Soil Sample



Sieves



Scale



Oven

Methodology

2

IV.

Data and Results Table 1 and 2 shows the measured mass of the sieves, along with the retained masses of soils after sieving for Trials 1 and 2.

Sieve Number

4 8 16 30 40 50 100 200 PAN

Sieve Opening Size (mm)

Mass of Sieve

4.75 2.36 1.18 0.6 0.425 0.3 0.15 0.075 N/A

487 474 433 405.5 384 374.5 346 336 363

Mass Retained (Sieve + Soil)(kg)

487 695.5 755.5 765 552.5 503.5 549.5 425 469.5

Mass Retained (Soil)(kg)

0 221.5 322.5 359.5 168.5 129 203.5 89 106.5

Table 1. Retained Masses of Soils in the Sieves for Trial 1

Sieve Number

4 8 16 30 40 50 100 200 PAN

Sieve Opening Size (mm)

Mass of Sieve

4.75 2.36 1.18 0.6 0.425 0.3 0.15 0.075 N/A

487 474 433.5 405.5 384 374.5 346.5 335.5 362.5

Mass Retained (Sieve + Soil)(kg)

487 677.5 750.5 760.5 558.5 505 550.5 429 485.5

Mass Retained (Soil)(kg)

0 203.5 317 355 174.5 130.5 204 93.5 123

Table 2. Retained Masses of Soils in the Sieves for Trial 2

Errors of the experiment were calculated by quantifying the deviation of the final total mass to the initial masses of the soils for each trial, as shown by the equation below: Equation 1 where

and are the initial and final masses of the soils. Using Equation 1, the

errors for trials 1 and 2 are as follows:

3

Since the errors for both trials are below the accepted value of 2.0%, the trials were both accepted. The cumulative percent retained in each sieve are also computed as follows: ∑

,

Equation 2

While percent finer is computed as: Equation 3 Using the Equations 2 and 3, the following sets of data were acquired: Sieve Number

Sieve Opening Size (mm)

4 8 16 30 40 50 100 200 PAN

4.75 2.36 1.18 0.6 0.425 0.3 0.15 0.075 N/A

Mass Retained (Soil)(kg)

0 221.5 322.5 359.5 168.5 129 203.5 89 106.5

Percent Retained (%)

0 13.84375 20.15625 22.46875 10.53125 8.0625 12.71875 5.5625 6.65625

Percent Passing (%)

100 86.15625 66 43.53125 33 24.9375 12.21875 6.65625 0

Table 3. Percent Passing Data for Corresponding Sieve Opening Sizes (Trial 1)

Sieve Number

Sieve Opening Size (mm)

4 8 16 30 40 50 100 200 PAN

4.75 2.36 1.18 0.6 0.425 0.3 0.15 0.075 N/A

Mass Retained (Soil)(kg)

0 203.5 317 355 174.5 130.5 204 93.5 123

Percent Retained (%)

Percent Passing (%)

0 12.71080575 19.80012492 22.17364147 10.89943785 8.151155528 12.74203623 5.840099938 7.682698314

100 87.2891943 67.4890693 45.3154279 34.41599 26.2648345 13.5227983 7.68269831 0

Table 4. Percent Passing Data for Corresponding Sieve Opening Sizes (Trial 2)

Particle size distribution graph is then obtained by plotting the sieve opening size on the x-axis versus the percent passing on the y-axis as presented below:

4

100 90

Percent Passing (%)

80

Trial 1

70 Trial 2

60 50

Sieve #10

40 Sieve #40 30 Sieve #200

20 10 0 10

1

0.1

0.01

Sieve Opening Size (mm) Graph 1: Over-laid Particle Size Distribution of the Soil Sample for Trials 1 and 2

In order to classify the grading of the soil sample, the coefficient of uniformity and curvature were calculated as follows: Equation 4 and 5 Wherein

is the coefficient of uniformity,

and , , and

is the coefficient of curvature,

are particle diameters at 60%, 30%, and 10% passing. Using

Equation 4 and 5, we then computed the coefficients as: For Trial 1:

For Trial 2:

5

V.

Analysis and Discussion Particle size analysis is widely used in classification of soils. The data acquired from particle size distribution curves is used in the design of filters for earth dams and to determine suitability of soil for road construction, air field, and others. Also, information obtained from particle size analysis is useful in describing the permeability, compaction, and other properties of soils. The experiment performed focuses on generating the particle size distribution of the soil sample. The generated particle size distribution graph is used in a lot of ways such as identifying the grading of the soil and the percentage of coarse materials and the fines. As shown in the above section we were able to calculate the coefficient of uniformity and curvature which were both used to conclude whether the soil is uniformly graded. The coefficients will be compared based on the Unified Soil Grading Criteria which is presented in the table below.

Criterion Uniformity Curvature

Material Gravel Sand Cu > 4

Cu > 6

1 < Cc < 3

1 < Cc < 3

Table 5. Unified soil grading criteria

Since the soil particles used all passed sieve #4, the soil sample is thus considered as containing of mostly of sands. Checking the values computed for the two trials, we see that both coefficient of uniformity,

of the two samples which were 10.3158

and 10.8889 are higher than 6. For the coefficient of curvature,

, we see that both

values which where 1.6337 and 1.7245 are both more than 1 but less than 3. And because the two trials of the soil samples were able to pass the criteria for uniformity and curvature, we then conclude that the soil is uniformly graded. Uniformly graded soils, like the soil sample, generally work best as a construction material. This is because of the arrangement of the soil particles that lessens the number of voids and improves compactability as we will see in experiment 3. Figure 1 shows the general formation of uniformly graded soils in contrast to others.

6

Figure 1. (i) Uniformly or Well Graded Soil Structure, (ii) Poorly Graded Soil, (iii) Gap Graded Soil Source: http://www.concretecountertopinstitute.com/

As we can see in Figure 1, a uniformly graded soil contains the least number of voids and thus is the densest in solids. We can also induce that these type of soil has greater strength against normal forces. Hence we can say that uniformly graded soils are more suitable as foundation supports than poorly and gap graded soils. Other than the grading of the soil, we can also see the percent of fines (particles that are less than 0.075 mm in diameter) are just 7 to 8% of the total soil mass, hence this would infer that the soil sample is not mainly affected by the Atterberg Limits that we were able to compute in Experiment 2, because of the dominant number of sandy particles than the fines. VI.

Conclusions and Recommendations

After thorough analysis it is concluded that the soil sample is uniformly graded and probably works best as a construction material. Also, it is inferred that because of the low number of fines, Atterberg limit which describes the fines will not be a great concern in contrasts to the physical properties of the sandy particles that greatly affects the strength of the soil sample. Note that because of the laboratory constraints, the hydrometer analysis which is used in order to identify the particle size distribution of the soil was not performed and thus the particle size distribution that was generated in this experiment is not complete. Errors in the experiment performed were assumed to be almost negligible as see that the distribution line of trials 1 and 2 are almost collinear as shown in Graph 1, which validates the experiment that was done. VII.

References 1. American Society for Testing and Materials. ASTM D422: Standard Test Method for Particle-Size Analysis of Soils. E-book. 2. Das, Braja M. Principles of Geotechnical Engineering. Published on 2002. E-book. 7

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